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AN10436 tda8932b/33(b) class-d audio amplifier rev. 01 ? 12 december 2007 application note document information info content keywords class-d amplifier, high efficiency, switch mode amplifier, flat tv. abstract this application note describes a st ereo switched mode amplifier (sma) for audio, based on either the td a8932b or tda8933(b) class-d audio amplifier device of nxp semiconductors, which has been designed for flat tv applications. the tda8932b device is the high-power version that delivers an output power of 2 10 w rms to 2 25 w rms in a single ended (se) configuration or 10 w rms to 50 w rms in a bridge tied load (btl) configuration. the tda8933(b) device is the low-po wer version that delivers an output power of 2 5 w rms to 2 15 w rms in a se configuration or 10 w rms to 30 w rms in a btl configuration. this high efficiency sma device has been designed to operate without a heat sink and has the flexibility to o perate from either an asymmetrical supply or a symmetrical supply with a wide range (10 v to 36 v or 5vto 18 v). the tda8932b/33(b) device utilizes two advanced features, the thermal foldback (tf) and the cycle-by-cycle current limiting to avoid audio holes (interruptions) during normal operation. in addition, the tda8932b/33 (b) utilizes integrated half supply voltage (hvp) buffers to simplify the design for an asymmetrical supply in the se configur ation. control logi c is integrated for a pop free transition between on/off. a sleep mode is incorporated to comply with the power saving regulations. an application designed around the tda 8932b/33(b) device is very robust because of the internal protection feat ures, such as a number of voltage protections, overcurrent protecti on (ocp) and overtemperature protection (otp).
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 2 of 55 contact information for additional information, please visit: http://www.nxp.com for sales office addresses, please send an email to: salesaddresses@nxp.com nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier revision history rev date description 01.00 20071212 first release
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 3 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier 1. introduction this application note describes a reference design of a switched mode amplifier (sma) for audio, based on the tda8932b or tda8933(b) device of nxp semiconductors operating from an asymmetrical supply. the tda8932b device and the tda8933(b) device are pin-to-pin compatible and can be used in either a stereo se configuration or a mono btl configuration. the tda8932b is the high-power version and the tda8933(b) is the low-power version. together they cover a wide power range per channel of 5 w rms to 50 w rms . the two versions are available in the so32 package (tda8932bt, tda8933t) and the htssop32 package (tda8932btw, tda8933btw). the tda8932b/33(b) class-d amplifier is intended for: ? flat tv application ? flat panel monitors ? multimedia systems, docking stations ? wireless speakers ? microsystems distinctive features ? high efficiency class-d audio amplifier due to a low r dson in se configuration. ? operates from a wide voltage range 10 v to 36 v (asymmetrical) or 5 v to 18 v (symmetrical). ? maximum power capability: ? tda8932b is 2 30 w rms short time output power in 4 se without heat sink. ? tda8933(b) is 2 20 w rms short time output power in 8 se without heat sink. ? cycle-by-cycle current limiting to avoi d interruption during normal operation. ? unique thermal foldback (tf) to avoid interruption during normal operation. ? integrated half supply voltage (hvp) buffers for reference and se output capacitance (asymmetrical supply). ? internal logic for pop free power supply on/off cycling. ? low standby current in sleep mode for power saving regulations. protection features ? window protection (wp) ? undervoltage protection (uvp) ? overvoltage protection (ovp) ? unbalance protection (ubp) ? overcurrent protection (ocp) ? overtemperature protection (otp) ? esd protection these features enable an engineer to desi gn a high performance, reliable and cost effective sma with only a small number of external components.
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 4 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier 1.1 block diagram 1.2 fixed frequency pulse widt h modulated class-d concept the tda8932b/33(b) device is a closed lo op fixed frequency pulse width modulated class-d amplifier with two differential analog inputs, each driving an independent power stage (see figure 2 ). the power stage consists out of a low side and a high side n-channel mosfet. fig 1. block diagram 001aaf597 2 10 31 8 28 29 27 3 12 tda8932b oscillator 26 boot1 v ddp1 out1 v ssp1 pwm modulator driver high driver low ctrl manager ctrl pwm modulator protections: ovp, ocp, otp, uvp, tf, wp stabilizer 11 v stabilizer 11 v regulator 5 v mode v dda 15 14 in1p oscref oscio v dda v ssd in1n inref in2p in2n 6 powerup 4 diag 7 cgnd 21 20 22 23 boot2 v ddp2 out2 25 stab1 24 stab2 18 11 dref hvpref 30 hvp1 19 hvp2 v ssp2 driver high driver low v dda v ssp1 v ssp2 v ssd v dda v ssa half supply voltage 5 engage 13 9 test v ssa 1, 16, 17, 32 v ssd(hw)
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 5 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier the tda8932b/33(b) can be configured for use in either se or btl. the major benefits of an se configuration compared to a btl conf iguration are cost and efficiency. this is because: ? only one pair of power switches is required for each channel. ? only one lp filter (inductor and film capacitor) is required for each channel. ? only two power stages for stereo in one package, therefore no heat sink required. an internal feedback network has a fixed closed loop gain of 30 db in the se configuration (36 db in the btl configuration). the pulse width modulation (pwm ) output signal has a oscillato r frequency that is fixed by either: ? an internal oscillator when configured as master. ? an external oscillator w hen configured as slave. the pulse width will be modulated according to the input signal. section 3 describes the complete application desi gn of the tda8932b/33(b) and includes the dimensioning of the lp output filter. 1.3 typical application circuits (simplified) 1.3.1 asymmetrical supply stereo se configuration the simplified application circuit of the tda8932b/33(b) device when operated from an asymmetrical supply (single supply) can be seen in figure 3 . the tda8932b/33(b) incorporates three integrated half supply voltage buffers to simplify the design for an asymmetrical supply in se co nfiguration. one buffer is for the reference decoupling capacitor (c hvpref ) on hvpref (pin 11) and two other buffers are for the two ac-couple capacitors (c se ) in series with the speaker. fig 2. tda8932b/33(b) in se configuration in1p 2 in1n 3 tda8932b/33(b) in2n 14 in2p 15 27 22 pwm out1 pwm out2 c se lp filter 010aaa00 0 c se lp filter
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 6 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier 1.3.2 symmetrical supply stereo se configuration the tda8932b/33(b) can operate also from a symmetrical supply (see figure 4 ). the three half supply voltage buffers are disabled. hvpref (pin 11), hvp1 (pin 30) and hvp2 (pin 19) should be connected to ground when supplied from a symmetrical supply. (1) the tda8933t device requires a 1 m resistor in parallel with the bootstrap capacitor cbo. tda8932bt, tda8932btw and tda8933btw devices do not require a 1 m resistor. fig 3. simplified se application tda 8932b/33(b) (asymmetrical supply) u1 tda8932b/ 33(b) v ssd(hw) 470 nf cin cen 470 nf v ssd(hw) in1p cinref 100 nf chvp 100 nf chvpref 47 f (25 v) cvddp 220 f (35 v) 470 nf cin 470 nf cin 470 nf cin 100 nf cosc 39 k rosc 10 rvdda mute control vpa sleep control cvdda 100 nf vp vpa vp gnd oscio in1n hvp1 diag v ddp1 engage boot1 powerup out1 cgnd v ssp1 v dda stab1 v ssa stab2 oscref v ssp2 hvpref out2 inref boot2 test v ddp2 in2n hvp2 in2p dref v ssd(hw) v ssd(hw) 010aaa41 8 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 18 17 20 19 22 21 24 23 26 25 32 31 30 29 28 27 + ? + ? csn 470 pf csn 470 pf rsn 10 rsn 10 llc llc cdref 100 nf hvp1 vp cstab 100 nf clc cvddp 100 nf cvddp 100 nf vp cbo 15 nf cvssp 100 nf cbo 15 nf cse hvp1 clc cse hvp2 chvp 100 nf hvp2 (1) (1)
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 7 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier a symmetrical supply has some benefits compar ed to an asymmetrical supply. first, the power bandwidth is not limited by the size of the se capacitor. therefore, for a full bandwidth (20 hz to 20 khz) amplifier, a symmetrical supply should be considered to avoid a large value se capacitor. secondly, when the supply is either unregulated and/or weak (e.g., a 50 hz / 60 hz transforme r), the output signal will not suffer from asymmetrical clipping (see section 4.4 ). 1.3.3 asymmetrical supply mono btl configuration the tda8932b/33(b) can operate in btl configuration when a high output power is required at a low supply voltage (e.g., for driving a subwoofer in a 2.1 system). see figure 5 . (1) the tda8933t device requires a 1 m resistor in parallel with the bootstrap capacitor cbo. tda8932bt, tda8932btw and tda8933btw devices do not require a 1 m resistor. fig 4. simplified se application tda 8932b/33(b) (symmetrical supply) u1 tda8932b/ 33(b) v ssd(hw) 470 nf cin cen 470 nf csn 470 pf csn 470 pf rsn 10 rsn 10 llc llc v ssd(hw) in1p cdref 100 nf cinref 100 nf cvddp 220 f (25 v) 470 nf cin 470 nf cin 470 nf cin 100 nf cosc 39 k rosc 10 rvdda mute control vdda vssa vss vss vssa vssa vssa vssa sleep control cvdda 100 nf vdd vdda 10 rvssa vss vssa vdd vss cvssa 100 nf cvssp 220 f (25 v) gnd oscio in1n hvp1 diag v ddp1 engage boot1 vdd powerup out1 cgnd v ssp1 v dda stab1 v ssa stab2 oscref v ssp2 hvpref out2 inref cstab 100 nf clc clc boot2 test v ddp2 in2n hvp2 in2p dref v ssd(hw) v ssd(hw) 010aaa41 9 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 18 17 20 19 22 21 24 23 26 25 32 31 30 29 28 27 vssa cvddp 100 nf cvddp 100 nf vss vdd cbo 15 nf + ? + ? cvssp 100 nf cbo 15 nf cvssp 100 nf vss (1) (1) vssa
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 8 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier 1.3.4 symmetrical supply mono btl configuration the tda8932b/33(b) can operate in btl configuration when high output powers are required at a low supply voltage (e.g., for driving a subwoofer in a 2.1 system). see figure 6 . (1) the tda8933t device requires a 1 m resistor in parallel with the bootstrap capacitor cbo. tda8932bt, tda8932btw and tda8933btw devices do not require a 1 m resistor. fig 5. simplified btl application t da8932b/33(b) (asymmetrical supply) u1 tda8932b/ 33(b) v ssd(hw) 470 nf cin cen 470 nf csn 470 pf rsn 10 llc llc v ssd(hw) in1p cinref 100 nf chvp 100 nf 470 nf cin 100 nf cosc 39 k rosc mute control vpa sleep control oscio in1n hvp1 diag v ddp1 engage boot1 powerup out1 cgnd v ssp1 v dda stab1 v ssa stab2 oscref v ssp2 hvpref out2 inref cstab 100 nf clc clc boot2 test v ddp2 in2n hvp2 in2p dref v ssd(hw) v ssd(hw) 010aaa42 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 18 17 20 19 22 21 24 23 26 25 32 31 30 29 28 27 cvddp 220 f (35 v) 10 rvdda cvdda 100 nf vp vpa vp gnd + ? hvpref csn 470 pf rsn 10 cdref 100 nf cvddp 100 nf vp cbo 15 nf chvp 100 nf rhvp 470 hvpref csn 470 pf rsn 10 hvpref vp cvddp 100 nf cbo 15 nf chvp 100 nf rhvp 470 (1) (1)
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 9 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier 2. functional ic description this chapter briefly describes the main functionality of the tda8932b/33(b) device and the different modes. it also describes th e different features and the protections implemented in the tda8932b/33(b). ta b l e 3 in section 2.8 in gives a description of each pin. 2.1 control inputs the tda8932b/33(b) is controlled by two inputs, powerup (pin 6) and engage (pin 5). the powerup is a two-level high impedance input. the engage input has an internal pull-up current source and an internal pull-down resistor of 100 k (typical). the internal pull-up current source is enabled after the power stages are (1) the tda8933t device requires a 1 m resistor in parallel with the bootstrap capacitor cbo. tda8932bt, tda8932btw and tda8933btw devices do not require a 1 m resistor. fig 6. simplified btl application tda8932b/33(b) (symmetrical supply) u1 tda8932b/ 33(b) v ssd(hw) cen 470 nf llc llc v ssd(hw) in1p cinref 100 nf 100 nf cosc 39 k rosc mute control vdda vssa vssa vssa vssa sleep control oscio in1n hvp1 diag v ddp1 engage boot1 powerup out1 cgnd v ssp1 v dda stab1 v ssa stab2 oscref v ssp2 hvpref out2 inref cstab 100 nf clc clc boot2 test v ddp2 in2n hvp2 in2p dref v ssd(hw) v ssd(hw) 010aaa421 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 18 17 20 19 22 21 24 23 26 25 32 31 30 29 28 27 cvddp 220 f (25 v) 10 rvdda cvdda 100 nf vdd vdda 10 rvssa vss vssa vdd vss cvssa 100 nf cvssp 220 f (25 v) gnd 1 f cin 1 f cin vss csn 470 pf rsn 10 vss vssa vdd cvddp 100 nf cbo 15 nf cvssp 100 nf csn 470 pf rsn 10 cdref 100 nf vssa cvddp 100 nf vdd cbo 15 nf cvssp 100 nf vss vss + ? (1) (1) vssa
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 10 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier enabled. the diag pin is an i/o indicating fa ult mode and it can be used to switch the amplifier in fault mode by means of an external pull-down to cgnd. the diag has an internal pull-up current source. [1] engage open pin voltage is 2.8 v in operating mode. [2] diag open pin voltage is 2.5 v in mute and operating mode. see section 3.3 for the recommended control circuitry of the powerup, engage and diag. remark: do not use an external pull-up resistor at the engage input, as it has its own internal pull-up current source. 2.1.1 mode description ? sleep mode : the sleep mode is incorporat ed to reduce the power co nsumption in system idle mode. in sleep mode, the in ternal 5 v stabilizer (dref), the 11 v stabilizers (stab1, stab2) and the half supply voltage buffers (hvpref, hvp1, hvp2) are disabled to reduce supply current consumption. ? mute mode : in mute mode, the 5 v (dref) and the 11 v (stab1, stab2) stabilizers will be enabled (internal logic bias ed) and the half supply voltage buffers will charge respectively the reference decouple capacitor (c hvpref ) and the ac-couple capacitors (c se ) in series with the speaker. the power stage is enabled (starts switching) after the se capacitors are charged completely. ? operating mode : in the operating mode, the gain of the dev ice is increased gradually to 30 db per output stage to avoid pop noise. the co mplete start-up se quence will take about 500 ms in a typical se application. ? fault mode : the fault mode is entered when one of the internal protections is triggered (see section 2.6 ) and as a consequence the diag (pin 4) is set to low. the internal pull-up current source of the engage pin is disabled in fault mode. therefore, the external capacitor will be discharged by means of the internal pull-down resistor. the fault mode can be entered also by means of an external pull-down to cgnd. ta b l e 2 shows an overview of the internal protections. table 1. control voltages referenced to cgnd mode v powerup (v) v engage (v) v diag (v) 1) sleep < 0.8 < 0.8 does not matter 2) mute > 2 < 0.8 > 2 [2] 3) operating > 2 > 2.4 [1] > 2 [2] 4) fault > 2 does not matter < 0.8
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 11 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier 2.2 half supply voltage (hvp) chargers the internal hvpref, hvp1 and hvp2 buffers will quickly charge th e reference capacitor (c hvpref ) and the se capacitors (c se ) before the power stage is enabled. the typical charge current of the hvp1 (pin 30) and the hvp2 (pin 19) buffers is 80 ma (dependent on the junction temperature). the charge ti me of the se capacitor can be estimated as follows: (1) where: c se = single ended capacitor (f) v dda = analog supply voltage (v) v ssa = negative analog supply voltage (v) i = typical charge current (a) example: charging an se capacitor of 1000 f at a supply voltage of 22 v takes about 138 ms. remark: the half supply voltage buffers are short circuit protected. 2.3 pop free power supply on/off cycling 2.3.1 supply turn-on internal logic will delay the ope ration (regardless of the control voltages) until the hvpref, hvp1 and hvp2 buffers are settled at ?(v dda ? v ssa ) to avoid pop noise. for an optimum pop performance, a capacitor of 470 nf should be attached to the engage (pin 5). this will make sure the gain and therefor e the offset will be increased gradually to avoid pop sound (see figure 21 ). 2.3.2 supply turn-off either the unbalance protection (ubp) or the undervoltage protection (uvp) will avoid pop noise when the power supply is turned off. the power stage is disabled when either v dda drops more than 20 % (see section 2.6.6 for more detail) or the uvp threshold level (9.5 v typical) is reached. remark: during power supply on/off cycling, an unwanted input signal from the audio source can still cause a pop noise. to prevent this the engage pin should be pulled down to cgnd to mute any unwanted signal. 2.4 oscillator frequency an external resistor connected be tween the oscref (pin 10) and v ssa sets the oscillator frequency of the pwm output. the oscilla tor frequency can be estimated with this equation: (2) t c se 0.5 v dda v ssa ? () ?? i -------------------------------------------------------------- = f osc 12.45 10 9 ? r osc -------------------------- =
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 12 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier where: r osc = resistor to set the oscillator frequency. the oscillator frequency can be se t between 250 khz and 500 khz. example: the use of a 39 k resistor will result in a oscilla tor frequency of about 320 khz. remark: a decouple capacitor of 100 nf should be connected across r osc for noise reduction. remark: synchronization is recommended when two or more tda8932b/33(b) devices are used in the same application (see section 2.5 ). 2.5 device synchronization synchronization is recommended to avoid possi ble audible beat tones from the speakers when two or more tda8932b/33(b) devices are used in the same application. synchronization can be achieved by connecting all oscios (pin 31) together and configuring one of the devices as master, while the other tda8932b/33(b) device is configured as slave (see figure 7 ). a device is configured as master when a resistor is connected between oscref (pin 10) and v ssa to set the oscillator freq uency. the oscio (pin 31) of the master is then configured as an oscilla tor output for synchronization. th e oscref (pin 10) of the slave devices should be shortened to v ssa to configure the oscio as an input. remark: in a 2.1 system, the se device for the l/r channel should be configured as master. remark: the maximum number of slaves driven by one master is 12. fig 7. device synchronization in a 2.1 system v ssa oscref oscio v ssa oscref oscio master l/r channel slave subwoofer channel tda8932b/33(b) 31 31 9 9 10 r osc 39 k c osc 100 nf 10 010aaa001 tda8932b/33(b) v ssa v ssa
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 13 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier 2.6 limiting and protection features the tda8932b/33(b) device ut ilizes two advanced limiting feat ures, the ther mal foldback and the cycle-by-cycle current limiting, to av oid audio holes (interruptions) during normal operation. in addition to these limiting features the dev ice has several protection features that make the tda8932b/33(b) very robust during a faul t condition. the following protections are incorporated: ? window protection (wp) ? undervoltage protections (uvp) ? overvoltage protection (ovp) ? unbalance protection (ubp) ? overcurrent protection (ocp) ? overtemperature protection (otp) when one of the above protecti ons is triggered, the device will enter the fault mode and the power stage is disabled immediately (floati ng). furthermore, an internal timer of about 100 ms is started and the diag (pin 4), refere nced to cgnd, is set lo w for the first 50 ms of the timer to indicate this protection status (fault mode). in addition the internal pull-up current of the engage pin is disabled in the fault mode, so the external capacitor will be discharged by means of the internal pull-down resistor (100 k ). after about 100 ms the device will restart (self-recovering), but only when the faul t condition has been resolved. a microcontroller can use the diagnostic sig nal (diag) to, e.g., shut down either the amplifier or the power supply. table 2. overview of all the limiting and pr otection features inside the tda8932b/33(b) feature trigger level diag output remark min typ max tf - 140 c - 150 c high unique thermal limiting to avoid audio holes when the junction temperature exceeds 140 c during normal operation. (see section 2.6.1 ) cycle-by-cycle current limiting tda8932b 4.0 a 5.0 a - high unique current limiting to avoid audio holes when the current exceeds the trigger level during normal operation. (see section 2.6.2 ) tda8933(b) 2.0 a 2.3 a - wp [1] low level 7.6 [1] --low [2] power stage stays floating and entering fault mode. (see section 2.6.3 ) high level 14.4 [1] -- uvp (v dda ? v ssa ) - 8.0 v 9.5 v 10 v low [2] power stage becomes floating entering fault mode. (see section 2.6.4 ) ovp (v dda ? v ssa ) - 36 v 38.5 v 40 v low [2] power stage becomes floating entering fault mode. (see section 2.6.5 ) ubp [3] low level - 17.6 v [3] -low [2] power stage becomes floating entering fault mode. (see section 2.6.6 ) high level - 29.3 v [3] -
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 14 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier [1] wp threshold level at v p = 22 v. see equation 3 and equation 4 for the threshold level versus the supply voltage. [2] diag is active low for at least 50 ms. [3] ubp threshold level at v p = 22 v. see equation 5 and equation 6 for the threshold level versus the supply voltage. 2.6.1 thermal foldback (tf) when the junction of the tda8932b/33(b) exceeds 140 c, the tf will gradually reduce the gain, limiting th e power dissipation. this means that the device will not switch off, but will continue to operate at a slightly lower gain , causing no audio holes (interruptions). the maximum junction temperature will not go be yond the absolute ma ximum temperature. therefore, a heat sink is not required and the thermal design becomes less critical and less temperature head room re quires to be taken into account since audio holes will not occur and the device will always stay wit hin the safe operating area (soa). 2.6.2 cycle-by-cycle current limiting when the output current of the devic e exceeds either 4 a (tda8932b) or 2 a (tda8933(b)), the cycle-by-cycle current limitation becomes active. this means the device will not switch off, but continue to opera te while limiting the cu rrent without causing audio holes (interruptions). the maximum output current will not go beyond the absolute maximum current. remark: when the cycle-by-cycle current limiting bec omes active, it will cause distortion. see section 3.2 for information on how to calculate the peak output current, depending on the supply voltage and the speaker impedance. 2.6.3 window protection (wp) wp checks the voltage at the pwm outputs (out1 pin 27 and out2 pin 22) before the power stage is enabled (trans ition from sleep mode to mu te / operating mode). to avoid large currents flowing, the wp is activated (power stage stays floating) in the event of a short from the pwm output to either v dd or v ss . the diag is set to low for at least 50 ms. the pwm output voltage where the wp becomes active at an asymmetrical supply can be calculated as follows: low threshold level: (3) ocp low ohmic short across the load tda8932b 4.0 a 5.0 a - low [2] power stage becomes floating entering fault mode. (see section 2.6.7 ) tda8933(b) 2.0 a 2.3 a - otp - 155 c - 160 clow [2] power stage becomes floating entering fault mode. (see section 2.6.8 ) table 2. overview of all the limiting and pr otection features inside the tda8932b/33(b) ?continued feature trigger level diag output remark min typ max v owp () l 11 32 ----- - v dda ? =
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 15 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier high threshold level: (4) where: v o(wp) = window protection output voltage (low or high). referenced to v ssa (v). v dda = analog supply voltage (v). the tda8932b/33(b) will recove r when the output voltage at out1 and out2 is within (21/32) v dda >v o >(11/32)v dda . 2.6.4 undervoltage protection (uvp) the tda8932b/33(b) requires a minimum supply voltage for proper operation. when the supply voltage drops below the uvp threshold level of 9.5 v (typical v dda ? v ssa ), the power stage becomes floating and the diag is set low for at least 50 ms. 2.6.5 overvoltage protection (ovp) an ovp is incorporated because an se class- d amplifier is able to increase the supply voltage when it is driven at low audio frequencies. this phenomenon is better known as "supply pumping" (see also section 4.3 ). the ovp prevents that supply pumping exceeds the absolute maximum su pply voltage rating of the tda8932b/33(b). this is a protection against self-destruction. the ovp threshold level is an internal fixed level at 38.5 v (typical v dda ? v ssa ). beyond this ovp threshold level the power stage will become floating and the diag is set low for at least 50 ms. remark: the ovp will neither preven t nor limit an overvolta ge caused by the power supply. 2.6.6 unbalance protection (ubp) the ubp senses the supply voltage unbalance between the analog supply voltages v dda and v ssa with respect to the hvpref voltage at pin 11. the ubp is triggered when the unbalance exceeds a certain level to avoid im proper biasing resulting in e.g. pop. the diag is set low and remain s low for at least 50 ms. the supply voltage where the ubp becomes active with an asymmetrical supply can be estimated as follows: low threshold level: (5) high threshold level: (6) where: v p(ubp) = unbalance protection supply voltage (low and high). v dda (pin 8) referenced to v ssa (v). v owp () h 21 32 ----- - v dda ? = v p ubp () l 8 5 -- - v hvpref ? = v p ubp () h 8 3 -- - v hvpref ? =
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 16 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier v hvpref = half supply voltage reference (pin 11) referenced to v ssa (v) the tda8932b/33(b) will recover w hen the supply voltage is within (8/5) v hvpref >v p >(8/3)v hvpref . the supply voltage at which the ubp becomes active with a symmetrical supply can be estimated as follows: low threshold level: (7) high threshold level: (8) where: v dda(ubp) = unbalance protection analog supply voltage. v dda (pin 8) referenced to v hvpref (v), hvpref is connected to gnd. v ssa = negative analog supply voltage (pin 9) referenced to v hvpref (v) example asymmetrical supply (use equation 5 and equation 6 ): at a supply voltage of 22 v, the voltage on hvpref is equal to v hvpref = 11 v. the hvpref voltage is buffered so the level will change only very slowly. when the supply voltage drops quickly (dv/dt > 4 v/s), the ubp is triggered below 17.6 v. when the supply voltage increases quickly, the ubp is triggered above 29.3 v. remark: with either an unregulated or a weak power supply, it might happen that this ubp is triggered, e.g., because of a voltage drop during a transient from no load to full load condition. see section 4.4 for more detail. 2.6.7 overcurrent protection (ocp) the ocp is activated only in a fault condition when the current exceeds 4 a (tda8932b) or 2 a (tda8933(b)) because of either a low ohmic short across the load or a low ohmic short from the demodulated output (after the inductor) to either v ss or v dd . the diag is set low for 50 ms and th e internal timer of 100 ms is star ted. the timer or the wp will keep the power stage disabled for at least 100 ms. as long as the short remains across the load, this cycle will repeat. th e average power dissipation in the tda8932b/33(b) will be low because the short circuit current will flow only during a very small part of the timer cycle of 100 ms. when the current exceeds 4 a (tda8932b) or 2 a (tda8933(b)) during normal operation, only the cycle-by-cycle current limiting is active without causing any audio holes (interruptions). see also section 2.6.2 . v dda ubp () l 3 5 -- - v ssa ? = v dda ubp () h 5 3 -- - v ssa ? =
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 17 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier 2.6.8 overtemperature protection (otp) the otp is activated only in a fault cond ition when the junction temperature exceeds 155 c (typical) e.g. during a short across the se capacitor. the diag output is set low for at least 50 ms and an internal timer of 100 ms is started. the timer will keep the power stage disabled for at least 100 ms. when the junction temperature exceeds 140 c during normal operation, the thermal foldback is active without causing any audio holes (interruptions). see also section 2.6.1 . 2.7 pinning information fig 8. pin configuration so32 tda8932bt tda8933t v ssd(hw) v ssd(hw) in1p oscio in1n hvp1 diag v ddp1 engage boot1 powerup out1 cgnd v ssp1 v dda stab1 v ssa stab2 oscref v ssp2 hvpref out2 inref boot2 test v ddp2 in2n hvp2 in2p dref v ssd(hw) v ssd(hw) 010aaa422 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 18 17 20 19 22 21 24 23 26 25 32 31 30 29 28 27
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 18 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier 2.8 pin description fig 9. pin configuration htssop32 tda8932btw tda8933btw v ssd(hw) v ssd(hw) in1p oscio in1n hvp1 diag v ddp1 engage boot1 powerup out1 cgnd v ssp1 v dda stab1 v ssa stab2 oscref v ssp2 hvpref out2 inref boot2 test v ddp2 in2n hvp2 in2p dref v ssd(hw) v ssd(hw) 010aaa423 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 18 17 20 19 22 21 24 23 26 25 32 31 30 29 28 27 table 3. pin description symbol pin description v ssd(hw) 1, 16, 17, 32 negative digital supply voltage and handle wafer connection (heat spreader). with an asymmetrical supply, the v ssd(hw) is connected to the supply gr ound. with a symmetrical supply, the v ssd(hw) is connected to the negative supply line, v ssa . in1p 2 positive audio input for power stage 1. in1n 3 negative audio input for power stage1. diag 4 input/output to indicate the fault mode. diag has an internal pull-up and should left floating when unused. engage 5 input with internal pull-up to switch between mute mode and operating mode. powerup 6 input to switch between sleep mode and mute mode. cgnd 7 control ground, reference for powerup, enga ge and diag. this cgnd is connected to the supply ground. v dda 8 positive analog supply voltage. v ssa 9 negative analog supply voltage. oscref 10 input to set the frequency for the internal osc illator (master configuration). in slave configuration this pin should be connected to v ssa . hvpref 11 decoupling of the internal half supply voltage reference (asymmetrical supply). with a symmetrical supply, this pin should be connected to the cgnd (supply ground). inref 12 decoupling for the input reference voltage. test 13 test signal input for testing purpose only (leave floating or connect to v ssa ). in2n 14 negative audio input for power stage 2. in2p 15 positive audio input for power stage 2. dref 18 decoupling of the internal 5 v regulator.
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 19 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier 3. design 2 x 5 w - 25 w audio amplifier (asymm etrical supply) this chapter describes a stereo amplifier reference design that is based on the tda8932bt or the tda8933(b)t device of nxp semiconductors (see the schematic section 3.10 ). this low-cost stereo single ended (se) amplifier design operates with an asymmetrical supply (10 v to 36 v). the tda8932bt and the tda8933(b)t devices are pin-to-pin compatible. the reference pcb, when mounted with tda8932bt (high-power version), can deliver a continuous time output power of 2 15 w rms into 4 (v p = 22 v) without a heat sink. the maximum short time output power is equal to 2 25 w rms into 4 (v p = 29 v). the reference pcb, when mounted with tda8933(b)t (low-power version), can deliver a continuous time output power of 2 15 w rms into 8 (v p = 31 v) without a heat sink. the maximum short time output power is equal to 2 18 w rms into 8 (v p = 34 v). this chapter shows the most important equati ons that can be used as a guideline for any design based on the tda8932b/33(b). 3.1 output power estimation the output power for the se and the btl conf iguration, just before clipping, can be estimated through the use of these equations: (9) hvp2 19 half supply voltage buffer for the se capacito r of output 2 (asymmetrical supply). with a symmetrical supply, this pin should be connected to the cgnd (supply ground). v ddp2 20 positive supply voltage for the power stage 2. boot2 21 bootstrap for the high-side driver, power stage 2. out2 22 pwm output, power stage 2. v ssp2 23 negative supply voltage for the power stage 2. stab2 24 decoupling of the internal 11 v regulator for power stage 2. stab1 25 decoupling of the internal 11 v regulator for power stage 1. v ssp1 26 negative supply voltage for the power stage 1. out1 27 pwm output, power stage 1. boot1 28 bootstrap for the high-side driver, channel 1. v ddp1 29 positive supply voltage for the power stage 1. hvp1 30 half supply voltage buffer for the se capacito r of output 1 (asymmetrical supply). with a symmetrical supply, this pin should be connected to the cgnd (supply ground). oscio 31 oscillator input in the slave configuration or the oscillator output in the master configuration. exposed die pad exposed die pad applicable to htssop32 package only. the exposed die pad should be connected to v ssd(hw) . table 3. pin description symbol pin description se: p o(0.5%) r l r l r dson r s r esr +++ ---------------------------------------------------------- ?? ?? 1t wmin () f osc ? ? () v p ?? ?? ?? 2 8r l ? ------------------------------------------------------------------------------------------------------------------------------- ---- =
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 20 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier (10) where: v p = supply voltage (v) (v ddp ? v ssp ) r l = load impedance ( ) r dson = on-resistance power switch ( ) r s = series resistance output inductor ( ) r esr = equivalent series resistance of se capacitance ( ) t w(min) = minimum pulse width (s) (80 ns typical) f osc = oscillator frequency (hz) (320 khz typical r7 = 39 k ) remark: equation 9 and equation 10 are valid only when: peak output current 4 a for tda8932b (see section 3.2 ). peak output current 2 a for tda8933(b). the output power at 10 % thd can be estimated as follows: (11) 3.1.1 tda8932b output power estimation figure 10 , figure 11 , figure 12 , and figure 13 show the estimated output power for the tda8932b at thd = 0.5 % and thd = 10 % as a function of the supply voltage for se and btl for different load impedances. btl: p o(0.5%) r l r l 2r dson r s + () ? + --------------------------------------------------- - ?? ?? 1t wmin () f osc ? ? () v p ?? ?? ?? 2 2r l ? ----------------------------------------------------------------------------------------------------------------------------- = p o(10%) 1.25 p o(0.5%) ? = a. thd+n = 0.5 % b. thd+n = 10 % fig 10. se output power as a function of supply voltage fig 11. se output power as a function of supply voltage v p (v) 10 40 30 20 20 10 30 40 p o (w) 0 r l = 4 6 8 001aad768 v p (v) 10 40 30 20 20 10 30 40 p o (w) 0 r l = 4 6 8 001aad769
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 21 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier remark: figure 10 and figure 11 are calculated with r dson =0.15 (at t j =25 c), r s =0.05 , r esr =0.05 and i o(ocp) = 4.0 a (minimum). remark: figure 12 and figure 13 are calculated with r dson =0.15 (at t j =25 c), r s =0.05 and i o(ocp) = 4.0 a (minimum). the horizontal parts in the figures indicate the region where current limiting becomes active, when a level of 4.0 a (minimum) is taken into account. it is recommended to avoid these regions because current limiting will cause unwanted distortion (see section 3.2 ). 3.1.2 tda8933(b) output power estimation figure 14 , figure 15 , figure 16 , and figure 17 show the estimated output power for the tda8933(b) at thd = 0.5 % and thd = 10 % as a function of supply voltage for se and btl for different load impedances. a. thd+n = 0.5 % b. thd+n = 10 % fig 12. btl output power as a function of supply voltage fig 13. btl output power as a function of supply voltage v p (v) 10 40 30 20 40 20 60 80 p o (w) 0 r l = 8 6 4 001aad770 v p (v) 10 40 30 20 40 20 60 80 p o (w) 0 r l = 8 6 4 001aad771
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 22 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier remark: figure 14 and figure 15 are calculated with r dson =0.39 (at t j =25 c), r s =0.05 , r esr =0.05 and i o(ocp) = 2.0 a (minimum). remark: figure 16 and figure 17 are calculated with r dson = 0.39 (at t j =25 c), r s =0.05 and i o(ocp) = 2.0 a (minimum). the horizontal parts in the figures indicate the region where current limiting becomes active when a level of 2.0 a (minimum) is taken into account. it is recommended to avoid these regions because current limiting will cause unwanted distortion (see section 3.2 ). a. thd+n = 0.5 % b. thd+n = 10 % fig 14. tda8933(b): se output power as a function of supply voltage fig 15. tda8933(b): se output power as a function of supply voltage v p (v) 10 40 30 20 10 5 15 20 p o (w) 0 r l = 8 6 4 010aaa105 v p (v) 10 40 30 20 10 5 15 20 p o (w) 0 r l = 8 6 4 010aaa108 a. thd+n = 0.5 % b. thd+n = 10 % fig 16. tda8933(b): btl output power as a function of supply voltage fig 17. tda8933(b): btl output power as a function of supply voltage v p (v) 10 20 18 14 16 12 010aaa106 10 5 15 20 p o (w) 0 r l = 6 r l = 8 v p (v) 10 20 18 14 16 12 010aaa107 10 5 15 20 p o (w) 0 r l = 6 r l = 8
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 23 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier 3.2 peak output cu rrent estimation the most important benefit of cycle-by-cycle current limiting is the loss of audio holes without requiring a lot of head room toward s the maximum peak output current of the tda8932b/33(b). the peak output current is limited internally above: ? 4 a minimum for the tda8932b. ? 2 a minimum for the tda8933(b). during normal operation, the output current should not exceed the threshold level of i o(ocp) = 4 a minimum (tda8932b) or i o(ocp) = 2 a minimum (tda8933( b)) because it will cause distortion. the peak output current in either se or btl can be estimated through the use of these equations: (12) (13) where: v p = supply voltage (v) (v ddp -v ssp ) r l = load impedance ( ) r dson = on-resistance power switch ( ) r s = series resistance output inductor ( ) r esr = equivalent series resistance of se capacitance ( ) example tda8932b (i o(ocp) = 4 a minimum): a 4 speaker in the se configuration can be used until a supply voltage of 33 v (approx.) without running into current limiting. a 4 speaker in the btl configuration can be used until a supply voltage of 17.5 v (approx.) without runn ing into current limiting. 3.3 control circuit the recommended powerup circuit is a resist or divider between the supply voltage and cgnd of the amplifier. optionally a transistor can be used to enter sleep mode to reduce the power consumption in e.g., system idle mode. se: i opeak () 0.5 v p ? r l r dson r s r esr +++ ---------------------------------------------------------- btl: i opeak () v p r l 2r dson r s + () ? + --------------------------------------------------- -
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 24 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier figure 19 and figure 20 show two alternative powerup circuits to control sleep mode from a 3.3 v or 5 v logic supply by means of a micro controller. remark: pull-up resistor should be 1k . an external capacitor of 470 nf is recommend ed at the engage pin. the switch in series with the internal pull-up curr ent source will be closed after th e power stage is enabled and finally the external capacitor will ?softly? engage the amplifier. softly m eans that the gain is gradually increased depending on the capacitor value (dv/dt) attached to the engage pin avoiding pop noise due to dc offset. fig 18. powerup circuit with optional sleep control optional circuit for sleep control operating sleep gnd 47 k 10 v .. 36 v 12 k 010aaa006 8 6 7 v dda powerup cgnd fig 19. sleep control push-pull output fig 20. sleep control open-drain output push-pull output operating sleep 3.3 v or 5 v 10 k 010aaa007 6 7 powerup cgnd 10 k open - drain output operating sleep 010aaa008 6 7 powerup cgnd 3.3 v or 5 v fig 21. engage circuit with optional mute control optional circuit for mute control operating sleep gnd 2.8 v 10 k 010aaa009 5 7 engage cgnd 470 nf 100 k 2 k 50 a
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 25 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier remark: do not use an external pull-up resistor at the engage input. remark: for a quick enable of the mute mode it is recommended to short circuit the 10 k series resistor. the diag pin can be used to: ? read out the status of respectively operating mode or fault mode. ? quickly disable the power stage in case of fault conditions at set level. the internal pull-up current is limited (approx. 50 a) therefore the maximum resistive load (referenced to cgnd) is 47 k . diag open pin voltage is 2.8 v (typ). the absolute maximum sink current of the diag pin should be limited to 5 ma (internal pull-down resistance r pd 1 k when set low). remark: the diag should be left floating when unused. 3.4 analog audio input the input signal is applied to the differentia l input of the tda8932b/33(b) by means of ac-couple capacitors (see figure 23 ). ac-couple capacitors are required for dc-blocking because the inputs (in1p, in1n, in2p and in2n) are biased at a voltage level of approximately +2.2 v (with respect to vss) w hen operating from an asymmetrical supply. at symmetrical supply, the inputs are bias ed at a voltage level of approximately ? 2.2 v (with respect to hvpref). the bias voltage is equal to the inref voltage (pin 12). remark: the input should be grounded close to the audio source (not at the amplifier side) to avoid a common ground with the power supply ground. fig 22. diag circuit to disable power stage optional circuit to disable power stage operating fault gnd 010aaa010 4 7 diag cgnd 100 k 1 k error 2.5 v 50 a fig 23. input circuitry 010aaa011 r i 100 k c5 c7 470 nf 470 nf r2 r3 4.7 k 4.7 k c6 330 pf in1p 2 in1n 3
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 26 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier 3.4.1 input impedance the input impedance of the tda832b/33(b) device is equal to r i =100k . a low pass rc filter (r2, r3 and c6) is applied to reduce the sensitivity for out-of-band disturbances. the closed loop voltage gain at 1 khz is equal to: (14) the cut-off frequency of the low-pass filter is equal to: (15) the ac couple capacitors form a high-p ass filter, with the total input impedance (r2 + r3 + r i ). the cut-off frequency of the high-pass filter is equal to: (16) example: substituting r2, r3 = 4.7 k and the ac-couple capacitors of c5, c7 = 470 nf in equation 16 results in a cut-off frequ ency of 6 hz, well below 20 hz. substituting r2, r3 = 4.7 k and c6 = 330 pf in equation 15 results in a cut-off frequency of 56 khz, well above 20 khz. 3.4.2 gain reduction the gain of the tda8932b/33(b) is fixed internally at 30 db for se configuration (or 36 db btl configuration). the gain can be reduced by a resistive voltage divider at the input (see figure 25 ). fig 24. input transfer function f ? 3db(l) f ? 3db(h) 0 db 010aaa01 2 g vcl () 20 r i r2 r3 r i ++ ------------------------------- ?? ?? log = f 3db h () ? 1 2 r2 r3 + () r i ? r2 r3 r i ++ ---------------------------------- c6 ?? --------------------------------------------------------- - = f 3db l () ? 1 2 r2 r3 r i ++ () c5 c7 ? c5 c7 ? ------------------ - ?? ?? ?? ---------------------------------------------------------------------------- - =
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 27 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier the closed-loop voltage gain g v(cl) when applying a resistiv e divider can be calculated through the use of this equation: (17) (18) where: r eq = equivalent resistance ( ) r p = parallel resistor ( ) r i = 100 k internal input resistance ( ) r2, r3 = series resistors ( ) g v(cl) = closed-loop voltage gain 30 db for se and 36 db for btl (db) example: substituting r2 = r3 = 4.7 k and r p =22k in equation 17 and equation 18 results in a gain of g v(tot) =26.3db. remark: applying a parallel resistance to r educe the gain will affect the cut-off frequencies of the input circuitry. it is requi red to compensate for this when requiring a 20 hz to 20 khz bandwidth. 3.4.3 reference decoupling (hvpref) the hvpref voltage (equal to ?(v dda ? v ssa )) is the reference for the output. the hvpref is created internally by a resistor divider (2 90 k ) located between v dda and v ssa . proper decoupling with 47 f and 100 nf is necessary to assure a good svrr in the se configuration. for the btl configuratio n, there is a requirement only for a 100 nf capacitor since any ripple on the hvpref is common for both output stages. 3.5 speaker configuration and impedance for a flat frequency response (second order butt erworth filter), it is necessary to change the low pass filter components l2 / l3 and c14 / c23 according to the speaker configuration and impedance. see figure 35 for more information. ta b l e 4 shows the required component values for speaker impedances of 4 , 6 or 8 . fig 25. resistive voltage divider at the input 010aaa01 3 r i 100 k c5 c7 470 nf 470 nf r2 r3 4.7 k 4.7 k c6 330 pf r p 22 k in1p 2 in1n 3 g vtot () g vcl () 20 r eq r eq r2 r3 + () + ----------------------------------------- ?? ?? log + = r eq r p r i ? r p r i + ----------------- =
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 28 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier 3.5.1 filter inductor there are two main types of inductors: ? air coil, current independent inductance and no saturation effect. ? inductor with a magnetic core (ferrite or iron powder): ? magnetically unshielded version (pot core). ? magnetically shielded version (pot core or toroidal core). an air coil is used often in hifi audio equipm ent, but is not very useful in mainstream audio because of the physical size. the major benefit of an unshielded inductor is cost. however, the magn etic stray field can cause either crosstalk issues or interference with other sensitive parts inside an audio or tv system (am-receiver, picture interference, etc.). the benefit of the shielded magnetic inductor is that the magnetic field is captured inside the core, reducing the magnetic stray field. the most important parameters of an inductor are: ? dc current rating to avoid magnetic saturation, causing an increase in audio distortion. ? linearity of the inductor, causing an increa se in audio distortion (especially above 1khz). ? dc resistance having a direct impact on efficiency. the dc current capability needs to be high enough to avoid magnet ic saturation. high peak currents are a result of saturation because the inductor tends to acts like a short. therefore, for a proper inductor selection it is important to consider the maximum current delivered by the amplifier, and the temper ature of the inductor (higher inductor temperature will decrease the sa turation level). the maximum current occurs at voltage clipping and can be calculated through the use of either equation 12 for se configuration or equation 13 for btl configuration. example: for a 2 15 w se amplifier operating at 22 v t he maximum output current is equal to 2.1 a (r dson =0.15 and r s =0.05 and r esr =0.06 ). therefore, it is recommended to select an indu ctor that retains still at least 80 % of the nominal inducta nce at the maximum current of 2.1 a. table 4. filter component values configuration impedance ( ) l2 / l3 ( h) c14 / c23 (nf) se 4 22 680 6 33 470 8 47 330 btl 4 10 1500 6 15 1000 8 22 680
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 29 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier remark: saturation will cause audio di stortion and severe satu ration might even damage the device. the inductor types listed below are recommended, based on audio and emc performance. remark: for emc purposes, it is important that the inner layer (for a multiple layer winding) is attached to the switching output to minimize electrical stray fields. the inner layer (start of the winding) is indicated with a dot mark on the inductor. in this way the outside layer acts like an electrical shielding for the inner layer attached to the output with fast alternating voltages. 3.5.2 filter capacitor a film capacitor is the best choice for aud io performance. howeve r, in most cases a ceramic smd capacitor (npo or x7r) will also give a satisfyi ng performance. the voltage rating of the filter capacitor should be 25 % higher than the maximum supply voltage v p in an asymmetrical application. in a symmetric al application the voltage rating should be 25 % higher than the half the maximum supply voltage (v ddp ? v ssp ). 3.5.3 zobel damping network a zobel network is recommended in every clas s-d amplifier application to damp the filter resonance (see in figure 26 r z and c z ). filter resonance will oc cur due to the inductive behavior (l e ) of the speaker voice coil. table 5. recommended inductor types brand and type l ( h) i sat (a) output power (w per channel) in r l =4 toko 16rhbp leaded, shielded 22 4.9 25 47 3.4 toko 11rhbp a7503cy leaded, shielded 22 2.21 15 47 1.60 toko ds86c b992as smd, shielded 22 2.0 10 47 1.4 sagami 7311na leaded, shielded 22 3.4 25 47 2.3 sagami 7e08n smd, shielded 22 2.6 15 47 1.8 fig 26. zobel damping network 010aaa426 v dd v ss pwm l lc c z r z l e r e c lc voice coil equivalent circuit
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 30 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier this zobel damping network is quite ef fective for a voice coil inductance l e <10l lc . the zobel damping network will lower th e resonance peak current in the filter inductor by at least 15 % to 40 % lowering the risk of unwanted inductor saturation. remark: besides inductor saturation a tweeter might also benefit from a zobel network since filter resonance can overstress the tweeter. ta b l e 6 contains the optimum damping resistors for different capacitor values: a minimum zobel damping network c z = 47 nf and r z =82 is strongly recommended. the optimum damping resistors are equal for 6 and 8 speakers when using the filter component values from ta b l e 4 , which are calculated based on f o =40khz. the resistor (r z ) should be able to at least dissipate the power when driving the amplifier with a 20 khz unclipped sine wave. figure 27 shows the sine wave power dissipation (2 0 khz) as a function of supply voltage. table 6. damping resistors for different capacitor values configuration speaker impedance ( ) l lc ( h) c lc (nf) c z (nf) r z ( ) ---4782 ---6856 single ended 4 22 680 100 39 ---15027 ---22022 (1) c z = 47 nf / r z = 82 (2) c z = 68 nf / r z = 56 (3) c z = 100 nf / r z = 39 (4) c z = 150 nf / r z = 27 (5) c z = 220 nf / r z = 22 fig 27. power dissipation as a function of supply voltage v p (v) 10 36 18 26 010aaa427 1 1.5 0.5 2 2.5 p (w) 0 (1) (2) (3) (4) (5)
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 31 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier remark: if the amplifier is driven at the resonance frequency (f o = 40 khz) of the filter, the power dissipation in the resistor will ri se causing the resi stor to overheat. 3.5.4 voltage clamp diodes for a voice coil inductance l e greater than 10 times the filter inductance (l lc ) the effectiveness of the zobel damping network is limited and the power dissipation in the resistor grows high, requiring bulky power resi stors. in general, mostly subwoofer voice coils and hifi multi-way speake rs have such a high inductance. remark: applications for which the end user is able to disconnect the speaker and operate the amplifier without speaker, might also suffer from issues of robustness because of the inductor saturation. to avoid inductor saturation in case of high i nductive load or no load, it is recommended to apply voltage clamp diodes at the output to the supply rails (see figure 28 ). relatively cheap general purpose diodes, like the 1n4001 (v r = 50 v) or the 1n4002 (v r = 100 v) can be used for this purpose. the reverse voltage of the diode should be at least 1.2 times the supply voltage and the repetitive peak current should be 1.2 times the maximum current of the amplifier. 3.6 single ended capacitor a single ended amplifier (class-ab or class-d) operating at an asymmetrical supply voltage will require an ac couple capacitor ( se capacitor) in series with the speaker. especially for a low output power (< 25 w) it is a very cost effectiv e solution compared to a btl configuration. it should be noted, th e se capacitor has no major drawback on thd and audio performance in general. the se capacitor forms a high-pass filter with the speaker impedance. therefore, the frequency response will roll off with 20 db per decade below the cut-off frequency f ? 3db . the cut-off frequency is equal to: (19) where: r l = load impedance ( ). c15 (c24) = single ended capacitance (f) (see schematic section 3.10 ). fig 28. voltage clamp diodes 010aaa428 v dd v ss pwm l lc d cl2 d cl1 c z r z l e r e c lc voice coil equivalent circuit f 3db ? 1 2 r l c15 ?? ------------------------------- - =
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 32 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier ta b l e 7 shows the required se capacitor values for a cut-off frequency of 60 hz, 40 hz and 20 hz. 3.6.1 voltage rating the voltage rating of the se capacitor should be at least equal to the nominal supply voltage v p in the application. this because th e voltage at the se capacitor can be modulated heavily when the amplifier is driven at either a low frequency or during an overload (a short circuit across the load or to v p ). in these situations the peak voltage at the se capacitor can be almost equal to the supply voltage. 3.6.2 lifetime the ambient temperature and the ripple current have the greatest effect on the lifetime of the aluminium electrolytic capacitors. for lifetime considerations the se capacitance must be able to at least handle the ripple current that is equal to the load current at ? rated output power. only ? of the rated output power is taken into account, because it is not likely that an audio amplifier is driven contin uously at rated output power over a lifetime. the ripple current at ? p rated is equal to: (20) where: r l = load impedance ( ) v p = supply voltage (v) (v ddp ? v ssp ) example: the ripple current of an amplifier that operates at 22 v with a 4 load (p rated =15w) is approximately 486 ma. this ripple current can be used to determine the expected lifetime of the se capacitor. most general purpose elec trolytic capacitors (85 c type) are capable already of handling a 486 ma ripple current. both the ripple current and the voltage rating must be considered to prevent the capacitor from failing. 3.7 bootstrap capacitor a 15 nf smd capacitor (npo or x7r) is required to drive the high side n-channel mosfet. the bootstrap capacitor is charged by means of an internal diode between the stab1 (pin 25) and the boot1 (pin 28) at the moment that the low side mosfet is on. table 7. values se capacitor impedance ( ) c15 / c24 ( f) f ? 3db = 60 hz f ? 3db = 40 hz f ? 3db = 20 hz 4 680 1000 2200 6 470 680 1500 8 330 470 1000 i 12 ? v p ? 2r l ? -------------------- - 1 4 -- - ? =
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 33 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier the voltage across the bootstrap capacitor is equal to v stab1 ? v f (forward voltage drop internal diode). therefore a voltage rating of 16 v is sufficient for the two bootstrap capacitors. remark: only the tda8933t device requires a 1 m across both bootstrap capacitors for discharging when the power stage becomes floating. 3.8 output rc snubber network an rc snubber network (see schematic section 3.10 ) reduces the voltage ringing at the power stage output (pin 22 and pin 27) after a voltage transition. a proper implementation of this rc snubber will improv e the emc performance (see figure 33 ). the worst case power dissipation in the snubber resistor r5 (r12) is equal to: (21) where: c9 (c29) = snubber capacitor (f) v p = supply voltage (v) (v ddp ? v ssp ) f osc = oscillator frequency (hz) example: substituting c9 = 470 pf, v p = 22 v and f osc = 320 khz in equation 21 , results in a power dissipation of 73 mw, requiring an 0805 smd. the voltage rating of the snubber capacitors (c9 and c26) should be 25 % higher than the maximum supply voltag e in the application. 3.9 layout recommendations the pcb design of an sma is probably the most difficult part of the design, because it might affect the audio performance, the emc performance, the ther mal performance, or even the functionality of the tda8932b/33(b). 3.9.1 emc considerations a double-sided pcb with plated through holes and 35 m copper is recommended, but a single layer is feasible as well. figure 29 shows a proposed floor plan of the crit ical components that contribute to a good audio and emc performance. the top side of this reference board is used to place the leaded components and the copper plane for thermal reasons. for more information on thermal considerations refer to section 3.9.2 . the bottom side of the double-layer pcb is used to place the smd components, including the tda8932b/33(b) and the majority of the signal tracks (see figure 30 to figure 33 ). p12 ? c9 v p () 2 2f osc ?? ?? =
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 34 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier some important notes for a proper layout are summarized below: ? input / output connectors at one side of the pcb (solid and "clean" star gnd connection). ? supply buffer capacitor (c1) close to the ic. ? filter inductor (l2, l3) close to the ic. ? filter capacitor (c14, c23) close to the output connector, together with the se capacitor (c15, c24). ? place the high frequency (hf) supply decoupling capacitor close to the ic (see figure 30 ). ? place the hf decoupling capacitor stab1/2 voltage close to the ic (see figure 31 ). ? place the bootstrap capacitor of the high-side driver close to the ic (see figure 32 ). ? place the rc output snubber network close to the ic (see figure 33 ). ? place the hf decoupling capacitor dref voltage close to the ic (see figure 33 ). fig 29. proposed floor plan of the components u1 filter inductor se capacitor filter capacitor large signal supply and output l2 l3 c15 c14 c23 c1 c24 audio outputs supply i/o connectors at one side solid ?clean? gnd small signal input tda8932b/33(b) audio inputs buffer capacitor 010aaa05 6
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 35 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier remark: smd components are on the bottom layer, viewed from the top. fig 30. hf decoupling supply c8, c25 fig 31. hf decoupling stab1/2 c17 c17 c9 c10 c4 32 u1 1 c18 r12 c31 c30 c3 16 17 29 26 23 20 c25 r5 15 010aaa060 c17 c9 c10 c4 32 u1 1 c18 r12 c31 c30 c3 16 17 29 c25 r5 15 26 25 24 23 010aaa061 fig 32. bootstrap capacitor high-side driver c10, c18 fig 33. rc output snubber network c17 c9 c10 c4 32 u1 1 c18 r12 c31 c30 c3 16 17 29 c25 r5 15 28 25 22 21 010aaa057 c17 c9 c10 c4 32 u1 1 c18 r12 c31 c30 c3 16 17 c25 r5 15 29 26 23 20 010aaa058 fig 34. hf decoupling dref c30 c17 c9 c10 c4 32 u1 1 c18 r12 c31 c30 c3 16 c25 r5 15 18 17 010aaa059
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 36 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier in general: ? minimizing the current loops that carry fa st alternating curren ts will reduce magnetic radiation. ? minimizing the length / size of the pwm output track (fast alternating voltages) as much as possible, will prevent capacitive coupling to the environment. otherwise this could lead to disturbances of high impedance inputs. 3.9.2 thermal considerations the thermal resistance is determined by the selected smd package, the pcb layout implementation and the airflow inside the final enclosure of the amplifier. the tda8932b/33(b) is available in two different thermally enhanced smd packages: ? tda8932bt/33t in so32 (sot287-1) package for reflow and wave solder process. ? tda8932btw/33btw in an htssop32 (sot549-1) package for reflow solder process only. thermal resistance so32 package the so32 package has special thermal corner leads, pins 1, 16, 17 and 32, increasing the power capability (reducing the overall r th(j-a) ) when soldered to a thermal copper plane at v ssa level. the so package is very suitab le for single layer pcb designs or pcb designs with limited space for a thermal plane. due to the package size the so32 is able to radiate a significant part of the heat directly into the air (thermal resistance is less depending on the heat transfer via the pcb). the thermal resistance of a s032 packag e will range from about 35 k/w to 50 k/w when mounted on a single or two layer pcb (free air natural convection). mo unting a heat sink can further decrease the thermal resistance with another 15 % to 25 %. the thermal resistance measured at the compact reference pcb (55 mm 45 mm) with s032 package can be found in section 5.3 . thermal resistance htssop32 package the htssop32 package has an exposed die-pad that only reduces the overall r th(j-a) significantly when soldered to a thermal copper plane at v ssa level (thermal resistance is strongly depending on the size and the nu mber of copper planes). this makes the htssop package very suitable for multilayer pc b designs with sufficient space for two or three thermal copper planes. when applying three thermal copper planes it is even possible to reach a continuous time output power of 2 25 w without a heat sink. the thermal resistance of a htssop32 package will range from about 25 k/w to 55 k/w when mounted on a multilayer pcb without heat sink (free air natural convection). increasing the area of the thermal copper planes, the number of planes, or the copper thickness will furt her reduce the thermal resistance r th(j-a) of both packages.
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 37 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier airflow inside enclosure at a set level the airflow inside the enclosur e will be limited compared to the situation in free air natural convection. th e airflow and other heat sources close to the amplifier will influence the temperature significantly. ther efore it is always recommended (and the responsibility of the set maker) to check the temperature beha vior in the final environment of the amplifier. remark: the tda8932b/33(b) amplifier with th e thermal foldback feature will never cause audio interruption (audio holes) due to the limited airflow and the limited presence of other heat sources close to the amplifier. therefore this thermal foldback feature will improve the reliable of the amplifier application under extreme temperature conditions because the device itself will always stay within the safe operating area (soa). thermal resistance measured thermal resistance of both the so32 and the htssop32 reference design can be found in section 5.3 . thermal via?s thermal via?s should be applied for an optimum heat flow to other layers of the pcb to reduce the r th(j ? a) . the thermal via?s should be placed close to corner leads and beyond the package for the so32 package (see pcb layout section 3.12 ). remark: do not use via?s with web construction , as they will have a high thermal resistance. thermal calculations to estimate the maximum junction temperature, equation 22 can be used: (22) where: t amb = ambient temperature (c) p = power dissipation in u1 (w) (see figure 50 or figure 61 , p versus p o ) r th(j ? a) = thermal resistance junction ambient (k/w) example: estimation of the junction temperature at p rated (for ftc requirements). power dissipation p = 2.5 w (see figure 47 ) at p rated =2 15 w in 4 . the estimated junction temperature at t amb =25 c and r th(j ? a) = 44 k/w, will be t j(max) =135 c (approx.) ( equation 22 ), staying below the tf threshold level of 140 c. at a p rated = 2 25 w in 4 the tf becomes active. the tf will gradually redu ce the gain and therefore reduce the long-term output power. see section 5.3 for the output power as a function of time, when the tf becomes active. the major benefit of the tf feature is that the amplifier is not switched off when it reaches the maximum junction temperature. remark: lifetime is guaranteed because the tda8932b/33(b) stays within the safe operating area due to the tf feature. t jmax () t amb r th j a ? () p ? +
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 38 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier remark: for thermal reliability and/or quality requirements on se t level, an average music power of ? p rated is assumed. this assumption can be made because audio amplifiers are not driven continuously at the rated output power. taking this into account, shows the major benefit of class-d as compared to class-ab. class-d dissipates less at ? p rated and that makes it possible to comply eas ily with the thermal re liability and/or quality regulations with a cheap so32 or ht ssop32 package without a heat sink. 3.10 schematic - revision 3.00 (1) the tda8933t device requires a 1 m in parallel with the bootstrap capacitor cbo. fig 35. schematic - version 3.00 v ssd/hw in1p in1n diag engage powerup cgnd v dda v ssa oscref hvpref inref in2n in2p test v ssd/hw v ssd/hw oscio hvp1 v ddp1 boot1 out1 v ssp1 stab1 stab2 v ssp2 out2 boot2 hvp2 v ddp2 v ssd/hw 1 2 3 4 5 6 7 8 9 10 11 13 14 12 15 in1 c5 470 nf 32 31 30 29 28 27 26 25 24 23 22 20 19 21 18 17 16 c11 470 nf r10 39 k c16 100nf c4 100 nf v p c10 15 nf (1) c9 470 pf c8 100 nf r5 10 c17 100 nf l3 22 h c18 15 nf (1) r12 10 c26 470 pf vp c25 100 nf v p = 10v ...35v gnd v p v pa c2 220 f/35 v c1 220 f/35 v r1 10 u1 tda8932bt /33t 010aaa062 hvp1 hvp2 c30 100 nf c31 100 nf r2 4.7 k r3 4.7 k c6 330 pf s1 r7 12 k sleep on r6 47 k v pa c20 47 f c21 100 nf c22 100 nf c29 470 nf in2 c27 470 nf r15 4.7 k r14 4.7 k c28 330 pf r4 10 k s2 mute operating 1 2 1 2 v pa r13 22 c19 100 nf 1 2 c23 680 nf c24 1000 f, 25 v hvp2 ? + out2 4 j4 r8 22 c12 100 nf 1 2 c14 680 nf c15 1000 f, 25 v hvp1 + ? out1 4 j3 l2 22 h c3 100 nf 1 2 j1 l1 bead j2 j5
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 39 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier 3.11 bill of materi als - revision 3.00 3.12 pcb layout - revision 2 double-sided pcb (55 mm 45 mm) with plated through holes (? = 0.6 mm), 35 m copper and fr4 base material. table 8. bill of materials item qty reference part description 1 2 c1, c2 220 f / 35 v general purpose 85 c, ? 8 mm 2 10 c3, c4, c12, c16, c17, c19, c21, c22, c30, c31 100 nf / 50 v smd 0805, x7r 3 5 c5, c7, c11, c27, c29 470 nf / 16 v smd 1206, x7r 4 2 c6, c28 330 pf / 16 v smd 0805, x7r 5 2 c8, c25 100 nf / 50 v smd 1206, x7r 6 2 c26, c9 470 pf / 50 v smd 0805, x7r 7 2 c10, c18 15 nf / 16 v smd 0805, x7r 8 2 c23, c14 680 nf / 63 v mkt-02 9 2 c24, c15 1000 f / 25 v general purpose 85 c ? 12.5 mm 10 1 c20 47 f / 25 v general purpose 85 c ? 6 mm 11 1 d1 led 3 mm led 12 3 j1, j3, j4 screw terminal camden electronics ctb3551/2 13 2 j2, j5 cinch - 14 1 l1 bead smd 1206, 742792115 / wrth elektronik or blm41pg600sn1l / murata 15 2 l3, l2 22 h 11rhbp / toko a7503cy-220m 16 3 r1, r5, r12 10 r smd 1206 17 5 r2, r3, r14, r15, r16 4.7 k smd 0805 18 1 r4 10 k smd 0805 19 1 r6 47 k smd 0805 20 1 r7 12 k smd 0805 21 2 r8, r13 22 r smd 2512 22 1 r10 39 k smd 0805 23 2 s2, s1 pcb switch 090320901 / secme 24 1 u1 tda8932bt sot287-1 (so32) / nxp semiconductors tda8933(b)t sot287-1 (so32) / nxp semiconductors
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 40 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier fig 36. top view, copper and silk screen top fig 37. top view, copper and silk screen bottom 010aaa078 010aaa110
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 41 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier 4. power supply 4.1 supply filtering a clc phi filter (c1, l1 and c2) is used to keep the high frequency (hf) currents locally around the amplifier (see figure 38 ). two 100 nf smd capacitors (c8 and c25) and an electrolytic buffer capacitor (c1) should be placed close to the amplifier to minimize the area of the hf current loops to avoid emission . the ferrite bead (l1) will avoid the flow of hf currents in (mostly) large supply voltage loops. the analog voltage (v dda ) of the tda8932b/33(b) requires an rc filter of 10 (r1) and 100 nf (c3) to avoid the hf noise entering the analog controller part of the device. 4.1.1 lifetime electrolytic capacitor the ambient temperature and the ripple current have the greatest effect on the lifetime of the aluminium electrolytic capacitors. the output power of an amplifier is assumed often to be ? of the total rated output power. at a power rating of 2 3.75 w (? 15 w) the lifetime is not an issue when general-purpose electrolytic capacitors (with a value of at least 220 f) are used. 4.2 supply gnd connection the best practice to avoid any common ground path with the power supply is to leave the supply floating. the power supply should be attached to gnd at the amplifier side. the differential input should be grounded at the sound processor and not at the amplifier side. fig 38. supply filtering power supply l1 ferrite bead tda8932b/33(b) 010aaa063 lp filter lp filter 29 26 c3 r1 10 ohm c1 c2 23 20 c8 c25 27 22 out 1 out 2 c15 c24 v dda pin 8 hf currents
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 42 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier 4.3 low frequency supply pumping effect a single ended (se) class-d amplifier will de liver energy back to the supply line (v p ) during the negative part of the audio signal. because most power supplies are not capable of sinking energy, the supply voltage will increa se especially when dr iving the amplifier at low audio frequencies. this phenomenon is often called the pumping effect. the voltage increase caused by the pumping effect depends on: ? the speaker impedance. ? the supply voltage. ? the audio signal frequency. ? the capacitance value of the supply line. ? the source/sink current of other channels (including the quiescent current of the amplifier). ? the current drawn from other circuits attached to the same supply line. this voltage increase might trigger the ovp of the audio amplifier and/or cause incorrect control behavior of the regulated power supply. the most effective way to overcome the pumping effect in a stereo se application is to apply one of the input signals to the negative input to invert the phas e of that particular output (see figure 40 ). fig 39. supply gnd connection gnd gnd power supply sound processor dac out gnd ferrite bead 100nf amplifier tda8932b/33(b) lp filter speaker differential input solid ground plane star ground amplifier side leave floating from ground (or use rc) 010aaa079 gnd
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 43 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier with this method, out1 and out2 are out of phase to minimize the pumping effect. the inversion of one of the outputs will also ha lve the peak current drawn from the power supply at a low audio frequency. remark: do not forget to change the polarity of the speaker connection of channel 2 to get the original phase of the signal from the speaker. 4.4 unregulated or weak power supply the voltage ripple of an unregulated power supply can be quite significant, due to: ? the output impedance (load regulation). ? a variation on the ac mains (line regulation). ? a cross regulation in a multiple output smps. therefore, when operating from an asymme trical supply, this vo ltage ripple will cause asymmetrical clipping. this might trigger al so the ubp (unbalance protection) when the voltage ripple exceeds either ? 20 % or +33 % of the nominal supply voltage (see also section 2.6.6 ). therefore, any unregula ted power supply (an auxilia ry voltage from either an smps or a 50 hz / 60 hz transformer) might need some attention to minimize the load, the line and the cross regulation. the voltage dip during a transient from no load condition to full load condition should be considered. the average supply current in full load for a stereo amplifier can be estimated as follows: (23) (24) where: p o = rms output power per channel (w) po = output power efficiency, audio amplifier fig 40. inverting the phase of one output and input (of channel 2) in1p 2 in1n 3 tda8932b/33(b) in2n 14 in2p 15 27 22 out1 out2 c15 lp filter 010aaa06 4 c24 lp filter se: i p(avg) 2p o ? po v p ? ------------------- = btl: i p(avg) p o po v p ? ------------------- =
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 44 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier v p = supply voltage (v) (v ddp - v ssp ) example: a 2 15 w amplifier at 22 v and 89 % efficien cy will draw an average supply current of 1.53 a. remark: for either a 50 hz / 60 hz transformer or a weak auxiliary supply, it might be worthwhile to consider the use of a symmetr ical supply to avoid asymmetrical clipping (early clipping of the positive output voltage). 5. performance characterization tda8932b 5.1 audio characterization se 5.1.1 performance figures se ta b l e 9 shows the measured performance figures of the tda8932bt two layer reference board (55 mm 45 mm) configured in se configuration. v p =22v, r l =2 4 se, f osc = 320 khz, f i = 1 khz, t amb =25 c unless specified otherwise. table 9. performance figures symbol parameters conditions / notes min typ max unit v p supply voltage operates down to uvp threshold level operates up to ovp threshold level 10 [1] -36 [1] v p o(rms) rms output power continuous time output power per channel - - - - r l = 4 -- - - thd+n = 10 % - 15.3 - w thd+n = 0.5 % - 12.1 - w r l = 8 , v p = 30 v - - - - thd+n = 10 % - 15.5 - w thd+n = 0.5 % - 12.3 - w short time output power - - - - r l = 4 , vp = 29 v - - - - thd+n = 10 % - 26.5 - w thd+n = 0.5 % - 21.1 - w thd+n total harmonic distortion-plus-noise p o = 1 w, aes17 brick wall filter 20 khz - - - - r l = 4 - 0.015 - % r l = 8 , v p = 30 v - 0.01 - % po output power efficiency p o =15w - - - - r l = 4 -92 - % r l = 8 , v p = 30 v - 93 - % g v(cl) closed-loop voltage gain v i = 100 mv rms , 1 khz, r i = 4.7 k , no load - 29.2 - db v i(sens) input sensitivity voltage p rated = 2 15 w - 305 - mv rms
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 45 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier [1] it is not recommended to operate the ic at the supply boundari es (10 v or 36 v) unless the supply is regulated well. 5.1.2 performance graphs se v n(o) noise output voltage mute mode - 70 - v operating mode, inputs shorted at inp, inn - 100 - v s/n signal to noise ratio unweighted, w.r.t. v o =7.8v rms -98 - db b bandwidth 3 db, c15 = c24 = 1000 f - 40 - 45,000 - hz svrr supply voltage ripple rejection r l = 4 , v ripple =500mv rms , 100 hz, inputs shorted -62 - db r l = 8 , v ripple =500mv rms , 100 hz, inputs shorted -60 - db cs channel separation p o = 1 w, 1 khz - 80 - db i p supply current total application; sleep mode, no load - 680 - a i q quiescent current total applicatio n; mute / operating mode - 53 - ma table 9. performance figures ?continued symbol parameters conditions / notes min typ max unit v p = 22 v, 2 4 se (1) = 6 khz (2) = 1 khz (3) = 100 hz v p = 30 v, 2 8 se (1) = 6 khz (2) = 1 khz (3) = 100 hz fig 41. thd+n as a function of output power fig 42. thd+n as a function of output power 001aad772 10 ? 1 10 ? 2 10 1 10 2 thd + n (%) 10 ? 3 p o (w/channel) 10 ? 2 10 2 10 10 ? 1 1 (1) (3) (2) 001aad773 10 ? 1 10 ? 2 10 1 10 2 thd + n (%) 10 ? 3 p o (w/channel) 10 ? 2 10 2 10 10 ? 1 1 (1) (3) (2)
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 46 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier v p = 22 v, 2 4 se (1) = 10 w (2) = 1 w v p = 30 v, 2 8 se (1) = 10 w (2) = 1 w fig 43. thd+n as a function of frequency fig 44. thd+n as a function of frequency 001aad774 10 ? 1 10 ? 2 10 1 10 2 thd + n (%) 10 ? 3 f i (hz) 10 10 5 10 4 10 2 10 3 (1) (2) 001aad775 10 ? 1 10 ? 2 10 1 10 2 thd + n (%) 10 ? 3 f i (hz) 10 10 5 10 4 10 2 10 3 (1) (2) v i = 100 mv rms , r i = 0 , c se = 1000 f (1) 2 4 se @ v p = 22 v (2) 2 8 se @ v p = 30 v v ripple = 500 mv rms w.r.t. gnd, shorted input r i = 0 (1) = 2 4 se @ v p = 22 v (2) = 2 8 se @ v p = 30 v fig 45. gain as a function of frequency fig 46. svrr as a function of frequency 001aad776 20 30 40 g v (db) 10 f i (hz) 10 10 5 10 4 10 2 10 3 (2) (1) 001aad777 ? 60 ? 40 ? 80 ? 20 0 svrr (db) ? 100 f i (hz) 10 10 5 10 4 10 2 10 3 (2) (1)
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 47 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier r i = 0 (1) 2 4 se @ v p = 22 v (2) 2 8 se @ v p = 30 v p o = 1 w, c hvpref = 47 f (1) = 2 4 se @ v p = 22 v (2) = 2 8 se @ v p = 30 v fig 47. s/n ratio as a function of output power fig 48. channel separation as a function of frequency 001aad778 p o (w/channel) 10 ? 2 10 2 10 10 ? 1 1 40 80 120 s/n (db) 0 (2) (1) 001aad779 ? 60 ? 40 ? 80 ? 20 0 cs (db) ? 100 f i (hz) 10 10 5 10 4 10 2 10 3 (1) (2) f i = 1 khz (1) 2 4 se @ v p = 22 v (2) 2 8 se @ v p = 30 v remark: po = (2 p o ) / (2 p o + p) f i = 1 khz (1) = 2 4 se @ v p = 22 v (2) = 2 8 se @ v p = 30 v remark: power dissipation in junction only. fig 49. efficiency as a function of output power fig 50. power dissipation as a function of output power p o (w/channel) 020 15 510 001aad780 40 60 20 80 100 po (%) 0 (2) (1) 001aad781 1.0 2.0 3.0 p (w) 0 p o (w/channel) 10 ? 2 10 2 10 10 ? 1 1 (2) (1)
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 48 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier 5.2 audio characterization btl 5.2.1 performance figures btl ta b l e 1 0 shows the measured performance figures of the tda8932bt two layer reference board (55 mm 45 mm) configured in btl configuration. v p = 22 v, r l =8 btl, f osc = 320 khz, f i = 1 khz, t amb = 25 c unless specified otherwise. f i = 1 khz (1) 2 4 se @ thd+n = 10 % (2) 2 4 se @ thd+n = 0.5 % (3) 2 8 se @ thd+n = 10 % (4) 2 8 se @ thd+n = 0.5 % fig 51. maximum output power as a function of supply voltage v p (v) 10 38 30 34 14 18 22 26 001aaf886 16 8 24 32 p o (w/channel) 0 (4) (1) (2) (3) table 10. performance figures symbol parameter conditions/notes min typ max unit v p supply voltage operates down to uvp threshold level; operates up to ovp threshold level 10 [1] -36 [1] v p o(rms) rms output power r l = 8 -- -- thd+n = 10 % - 32.1 - w thd+n = 0.5 % - 25.7 - w r l = 4 ; v p = 12 v - - - - thd+n = 10 % - 17.2 - w thd+n = 0.5 % - 13.2 - w thd+n total harmonic distortion-plus-noise p o = 1 w, aes17 brick wall filter 20 khz - - - - r l = 8 -0.007 -% r l = 4 , vp = 12 v - 0.02 - % po output power efficiency p o =15w, v p = 22 v, r l = 8 -90 -% p o =30w, v p = 12 v, r l = 4 -92 -%
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 49 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier [1] it is not recommended to operate the ic at the supply boundari es (10 v or 36 v) unless the supply is regulated well. 5.2.2 performance graphs btl g v(cl) closed-loop voltage gain v i = 100 mv rms , 1 khz, r i = 4.7 k , no load - 35.2 - db v i(sens) input sensitivity voltage p rated = 30 w, r i = 4.7 k -305 -mv rms v n(o) noise output voltage mute mode - 25 - v operating mode, inputs shorted at inp, inn - 100 - v s/n signal-to-noise ratio unweighted, in relation to v o = 15.5 v rms -104 -db b bandwidth 3 db 0 to 45,000 hz svrr supply voltage ripple rejection r l = 8 w, v ripple = 500 mv rms , 100 hz, inputs shorted -77 -db r l = 4 w, v ripple = 500 mv rms , 100 hz, inputs shorted -77 -db i p supply current sleep mode, no load - 680 - a i q quiescent current mute / operating mode - 53 - ma table 10. performance figures ?continued symbol parameter conditions/notes min typ max unit v p = 22 v, 8 btl (1) 6 khz (2) 1 khz (3) 100 hz v p = 12 v, 4 btl (1) 6 khz (2) 1 khz (3) 100 hz fig 52. thd+n as a function of output power fig 53. thd+n as a function of output power 001aad783 10 ? 1 10 ? 2 10 1 10 2 thd + n (%) 10 ? 3 p o (w) 10 ? 2 10 2 10 10 ? 1 1 (1) (2) (3) 001aad782 10 ? 1 10 ? 2 10 1 10 2 thd + n (%) 10 ? 3 p o (w) 10 ? 2 10 2 10 10 ? 1 1 (1) (2) (3)
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 50 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier v p = 22 v, 8 btl (1) 10 w (2) 1 w v p = 12 v, 4 btl (1) 10 w (2) 1 w fig 54. thd+n as a function of frequency fig 55. thd+n as a function of frequency 001aae114 10 ? 1 10 ? 2 10 1 10 2 thd + n (%) 10 ? 3 f i (hz) 10 10 5 10 4 10 2 10 3 (1) (2) 001aae115 10 ? 1 10 ? 2 10 1 10 2 thd + n (%) 10 ? 3 f i (hz) 10 10 5 10 4 10 2 10 3 (2) (1) v i = 100 mv rms , r i = 0 (1) 4 btl @ v p = 12 v (2) 8 btl @ v p = 22 v v ripple = 500 mv rms in relation to gnd, shorted input, r i = 0 (1) 4 btl @ v p = 12 v (2) 8 btl @ v p = 22 v fig 56. gain as a function of frequency fig 57. svrr as a function of frequency 001aae116 20 30 40 g v (db) 10 f i (hz) 10 10 5 10 4 10 2 10 3 (1) (2) 001aae117 ? 60 ? 40 ? 80 ? 20 0 svrr (db) ? 100 f i (hz) 10 10 5 10 4 10 2 10 3 (1) (2)
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 51 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier r i = 0 (1) 4 btl @ v p = 12 v (2) 8 btl @ v p = 22 v f i = 1 khz (1) 4 btl @ thd+n = 10 % (2) 4 btl @ thd+n = 0.5 % (3) 8 btl @ thd+n = 10 % (4) 8 btl @ thd+n = 0.5 % fig 58. s/n ratio as a function of output power fig 59. maximum output power as a function of supply voltage 001aae118 p o (w) 10 ? 2 10 2 10 10 ? 1 1 40 80 120 s/n (db) 0 (2) (1) 001aaf893 v p (v) 10 34 26 18 14 30 22 40 50 30 20 10 60 70 p o (w) 0 (2) (1) (3) (4) f i = 1 khz (1) 4 btl @ v p = 12 v (2) 8 btl @ v p = 22 v remark: po = (p o ) / (p o + p) f i = 1 khz (1) 4 btl @ v p =12 v (2) 8 btl @ v p =22 v remark: power dissipation in junction only fig 60. efficiency as a function of output power fig 61. power dissipation as a function of output power 001aae119 p o (w) 030 20 10 40 60 20 80 100 po (%) 0 (2) (1) 001aae120 1.0 2.0 3.0 p (w) 0 p o (w) 10 ? 2 10 2 10 10 ? 1 1 (2) (1)
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 52 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier 5.3 thermal characterization the measured thermal resistance of the re ference design with an so32 package, a double-sided fr4 pcb (55 mm 45 mm) and 35 m copper, is equal to 44 k/w (free air and natural convection). when the junction temperature reaches the threshold level of the thermal foldback (140 c to 150 c), it starts to reduce gradually the output power so the maximum temperature will stay always withi n the safe operating area. figure 62 and figure 63 show the tda8932bt (s032) output power as a function of time at different supply voltages. the tota l output power of the device is 2 p o , because the measurement is performed at se configuration. figure 64 and figure 65 show the tda8932bt output po wer as a function of time at different supply voltages. total output power of the device is 1 p o because the measurement is performed at btl configuration. r l = 2 4 se; f i = 1 khz; 2 layer so32 application board (55 mm 45 mm) without heat sink. (1) v p = 22 v (2) v p = 26 v (3) v p = 29 v r l = 2 8 se; f i = 1 khz; 2 layer so32 application board (55 mm 45 mm) without heat sink. (1) v p = 30 v (2) v p = 34 v fig 62. se output power as a function of time fig 63. se output power as a function of time t (s) 0 600 480 240 360 120 001aaf887 16 8 24 32 0 p o (w/channel) (2) (1) (3) t (s) 0 600 480 240 360 120 001aaf888 16 8 24 32 0 p o (w/channel) (2) (1)
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 53 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier 5.4 emi characterization (fcc) the tda8932b/33(b) reference design ca n comply easily with the fcc radiated emissions standards with 1 m of cable attached to all the i/os. the spectrum analyzer is set at max hold and the output power is 2 1/8 p rated . r l = 4 ; f i = 1 khz; 2 layer so32 application board (55 mm 45 mm) without heat sink. (1) v p = 12 v (2) v p = 13.5 v (3) v p = 15 v r l = 8 ; f i = 1 khz; 2 layer so32 application board (55 mm 45 mm) without heat sink. (1) v p = 22 v (2) v p = 26 v (3) vp = 29 v fig 64. btl output power as a function of time fig 65. btl output power as a function of time t (s) 0 600 480 240 360 120 001aaf896 16 8 24 32 0 p o (w) (2) (1) (3) t (s) 0 600 480 240 360 120 001aaf899 20 40 60 10 30 50 p o (w) 0 (2) (1) (3) fig 66. 150 khz to 30 mhz fig 67. 30 mhz to 300 mhz ref 80.0 db w atten 10 db start 150 khz res bw 10 khz stop 30.00 mhz swp 750 msec display line 50.0 db v 010aaa102 dl 50.0 db v vbw 10 khz battery 010aaa101 ref 50.0 db w atten 10 db start 30 mhz res bw 100 khz stop 300.0 mhz swp 200 msec battery display line 50.0 db v dl 50.0 db v vbw 30 khz
AN10436_1 ? nxp b.v. 2007. all rights reserved. application note rev. 01 ? 12 december 2007 54 of 55 nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier 6. legal information 6.1 definitions draft ? the document is a draft versi on only. the content is still under internal review and subject to formal approval, which may result in modifications or additions. nxp semiconductors does not give any representations or warranties as to the accuracy or completeness of information included herein and shall hav e no liability for the consequences of use of such information. 6.2 disclaimers general ? information in this document is believed to be accurate and reliable. however, nxp semiconductors d oes not give any representations or warranties, expressed or implied, as to the accuracy or completeness of such information and shall have no liability for the consequences of use of such information. right to make changes ? nxp semiconductors reserves the right to make changes to information published in this document, including without limitation specifications and product descriptions, at any time and without notice. this document supersedes and replaces all information supplied prior to the publication hereof. suitability for use ? nxp semiconductors products are not designed, authorized or warranted to be suitable for use in medical, military, aircraft, space or life support equipment, nor in applications where failure or malfunction of an nxp semiconductors product can reasonably be expected to result in personal injury, death or severe property or environmental damage. nxp semiconductors accepts no liability for inclusion and/or use of nxp semiconductors products in such equipment or applications and therefore such inclusion and/or use is at the customer?s own risk. applications ? applications that are described herein for any of these products are for illustrative purpos es only. nxp semiconductors makes no representation or warranty that such applications will be suitable for the specified use without further testing or modification. 6.3 trademarks notice: all referenced brands, produc t names, service names and trademarks are the property of their respective owners.
nxp semiconductors AN10436 tda8932b/33(b) class-d audio amplifier ? nxp b.v. 2007. all rights reserved. for more information, please visit: http://www.nxp.com for sales office addresses, please se nd an email to: salesaddresses@nxp.com date of release: 12 december 2007 document identifier: AN10436_1 please be aware that important notices concerning this document and the product(s) described herein, have been included in section ?legal information?. 7. contents 1 introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1 block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.2 fixed frequency pulse width modulated class-d concept . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.3 typical application circuits (simplified) . . . . . . . 5 1.3.1 asymmetrical supply st ereo se configuration . 5 1.3.2 symmetrical supply stereo se configuration . . 6 1.3.3 asymmetrical supply mono btl configuration . 7 1.3.4 symmetrical supply mono btl configuration . . 8 2 functional ic description . . . . . . . . . . . . . . . . . 9 2.1 control inputs . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2.1.1 mode description . . . . . . . . . . . . . . . . . . . . . . 10 2.2 half supply voltage (hvp) chargers. . . . . . . . 11 2.3 pop free power supply on/off cycling . . . . . . . 11 2.3.1 supply turn-on . . . . . . . . . . . . . . . . . . . . . . . . 11 2.3.2 supply turn-off . . . . . . . . . . . . . . . . . . . . . . . . 11 2.4 oscillator frequency . . . . . . . . . . . . . . . . . . . . 11 2.5 device synchronization. . . . . . . . . . . . . . . . . . 12 2.6 limiting and protection features . . . . . . . . . . . 13 2.6.1 thermal foldback (tf) . . . . . . . . . . . . . . . . . . 14 2.6.2 cycle-by-cycle current limiting . . . . . . . . . . . . 14 2.6.3 window protection (wp). . . . . . . . . . . . . . . . . 14 2.6.4 undervoltage protection (uvp) . . . . . . . . . . . 15 2.6.5 overvoltage protection (ovp) . . . . . . . . . . . . 15 2.6.6 unbalance protection (ubp) . . . . . . . . . . . . . 15 2.6.7 overcurrent protection (ocp) . . . . . . . . . . . . 16 2.6.8 overtemperature protection (otp) . . . . . . . . 17 2.7 pinning information . . . . . . . . . . . . . . . . . . . . . 17 2.8 pin description . . . . . . . . . . . . . . . . . . . . . . . . 18 3 design 2 x 5 w - 25 w audio amplifier (asymmetrical supply) . . . . . . . . . . . . . . . . . . . 19 3.1 output power estimation. . . . . . . . . . . . . . . . . 19 3.1.1 tda8932b output power estimation . . . . . . . . 20 3.1.2 tda8933(b) output power estimation. . . . . . . 21 3.2 peak output current estimation . . . . . . . . . . . . 23 3.3 control circuit . . . . . . . . . . . . . . . . . . . . . . . . . 23 3.4 analog audio input . . . . . . . . . . . . . . . . . . . . . 25 3.4.1 input impedance . . . . . . . . . . . . . . . . . . . . . . . 26 3.4.2 gain reduction . . . . . . . . . . . . . . . . . . . . . . . . 26 3.4.3 reference decoupling (hvpref). . . . . . . . . . 27 3.5 speaker configuration and impedance . . . . . . 27 3.5.1 filter inductor . . . . . . . . . . . . . . . . . . . . . . . . . 28 3.5.2 filter capacitor . . . . . . . . . . . . . . . . . . . . . . . . 29 3.5.3 zobel damping network . . . . . . . . . . . . . . . . . 29 3.5.4 voltage clamp diodes . . . . . . . . . . . . . . . . . . . 31 3.6 single ended capacitor . . . . . . . . . . . . . . . . . . 31 3.6.1 voltage rating . . . . . . . . . . . . . . . . . . . . . . . . . 32 3.6.2 lifetime . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 3.7 bootstrap capacitor . . . . . . . . . . . . . . . . . . . . 32 3.8 output rc snubber network . . . . . . . . . . . . . 33 3.9 layout recommendations. . . . . . . . . . . . . . . . 33 3.9.1 emc considerations. . . . . . . . . . . . . . . . . . . . 33 3.9.2 thermal considerations . . . . . . . . . . . . . . . . . 36 3.10 schematic - revision 3.00. . . . . . . . . . . . . . . . 38 3.11 bill of materials - revision 3.00 . . . . . . . . . . . . 39 3.12 pcb layout - revision 2 . . . . . . . . . . . . . . . . . 39 4 power supply. . . . . . . . . . . . . . . . . . . . . . . . . . 41 4.1 supply filtering . . . . . . . . . . . . . . . . . . . . . . . . 41 4.1.1 lifetime electrolytic capacitor . . . . . . . . . . . . . 41 4.2 supply gnd connection. . . . . . . . . . . . . . . . . 41 4.3 low frequency supply pumping effect . . . . . . 42 4.4 unregulated or weak power supply . . . . . . . . 43 5 performance characterization tda8932b. . . 44 5.1 audio characterization se . . . . . . . . . . . . . . . 44 5.1.1 performance figures se. . . . . . . . . . . . . . . . . 44 5.1.2 performance graphs se. . . . . . . . . . . . . . . . . 45 5.2 audio characterization btl . . . . . . . . . . . . . . 48 5.2.1 performance figures btl . . . . . . . . . . . . . . . . 48 5.2.2 performance graphs btl. . . . . . . . . . . . . . . . 49 5.3 thermal characterization . . . . . . . . . . . . . . . . 52 5.4 emi characterization (fcc) . . . . . . . . . . . . . . 53 6 legal information . . . . . . . . . . . . . . . . . . . . . . 54 6.1 definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 6.2 disclaimers . . . . . . . . . . . . . . . . . . . . . . . . . . 54 6.3 trademarks . . . . . . . . . . . . . . . . . . . . . . . . . . 54 7 contents. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

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