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Preliminary
TMPA421DS
Rev.2.0 December 20, 2005
15W + 6W x 2
2.1 Channel CLASS-D AUDIO POWER AMPLIFIER
GENERAL DESCRIPTION
FEATURES
The TMPA421DS is a 2.1 Channel Class-D output Integrated 2.1 channel power amplifier in one audio power amplifier for driving speakers with high power efficiency. The bass output is designed as BTL (Bridge-Tied-Load) for high chip 15W + 6W x 2 2.1 Channel Class-D Output
output power. The right& left channels are Power efficiency is up to 82% designed as SE (Single-Ended). The outputs are Convenient gain control able to drive 4, 6, 8 or 16 speakers. The output power can be up to 15W for bass and 6W Time delay for de-pop control for either Right or Left channel. No external heat-sink is necessary. The gain of the amplifier is defined by either gain0/gain1 gain control or by input resistance. Thermal protection and short-circuit protection are integrated for safety purpose. The internal de-pop circuitry eliminates pop noise at power-up & shutdown operations. Thermal Protection Output Pin Short-Circuit Protection (Short to Other Outputs, Short to VCC, Short to Ground) Low Quiescent Current (10mA Typical at 12V) Low Current in Shutdown Mode (<1A Typical) Separate VCC & PVCC Regulated 5-V Supply Output
For best performance, please refer to
APPLICATIONS
TMPA421DS is convenient for 2.1 channel
http://www.taimec.com.tw/English/EVM.htm http://www.class-d.com.tw/English/EVM.htm
applications. It can be used for LCD Monitors, for PCB layout. TVs, DVD Players, Powered Speakers or any 2.1 channel power amplifiers.
PACKAGE
TQFP48L available
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Preliminary
TMPA421DS
Rev.2.0 December 20, 2005
REFERENCE CIRCUIT
BOUTC1 1uF L5 33uH
BO UT+ C2 1uF L6 33u H
D1 DIO DE PV CC + C15 10uF CC C18 (optional) PV 1000uF(16V) + C22 0.1uF C23 0.1 uF
D2 DIO DE
48 47 46 45 44 43 42 41 40 39 38 37
U1 1 2 3 C5 0.47uF 4 C11 1uF 5 C6 6.8nF 6 C3 6.8nF 7 C12 1uF 8 9 GAINO 10 GA IN1 11 12 SHUT D OWN C4 0.47uF SD BIN N BIN P HF VDD B RIN LIN HF VDD AGND GAINO GAIN1 NC NC NC PVCCB PVCCB BOU TN BOU TN PGNDB PGNDB BOU TP BOU TP PVCCB PVCCB NC 36 35 34 33 32 31 30 29 AVDD 28 27 26 25
BASS IN PUT RIGHT INPU T LEFT IN PUT
421DS
13 14 15 16 17 18 19 20 21 22 23 24
NC PV CCL PV CCL LO UT LO UT PG NDL PG NDR ROU T ROU T PV CCR PV CCR NC
NC NC NC AVCC NC NC AGND VDDZ AVDD HF RC AGND NC
VC C C24 0.1uF C13 1uF + C14 10uF + C16 10u F
PVCC C25 0.1uF + C17 10uF D3 DIO DE L7 33uH L8 33u H PV CC C26 0.1uF + C18(optional) 1000uF(16V) PV CC D4 DIO DE R12 100
VC C
C7 1uF + C28 47uF RO UT + C29 47uF LO UT
C8 1uF
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Preliminary
TMPA421DS
Rev.2.0 December 20, 2005
Please email david@taimec.com.tw for complete datasheet.
Tai-1 Microelectronics reserves the right to make corrections, modifications, enhancements, improvements, and other changes to its products and services at any time and to discontinue any product or service without notice. Customers are responsible for their products and applications using Tai-1 Microelectronics components.
Note that the external components or PCB layout should be designed not to generate abnormal voltages to the chip to prevent from latch up which may cause damage to the device.
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Preliminary
TMPA421DS
Rev.2.0 December 20, 2005
Typical Application
BO UTC1 1uF ) (16V L5 33uH
BO UT+ C2 1uF ) (16V L6 33uH
D1 DIO DE(optional) PV CC C15 + 10uF(16V ) C22 0.1uF(16V) CC C18(optional) PV 1000uF(25V) + C23 0.1uF(16V)
D2 DIO DE(optional)
PV CC
R7 6k C9 33nF(6.3V) R8 12k J1 RIN R5 12k PH ONEJACKSTE REO R6 22k SD
R9 10k 1 switch S1 2 C4 1uF (6.3V ) 3 C5 1uF (6.3V 4 ) C11 1uF (6.3V ) 5 C6 6.8nF(6.3V) 6 C3 6.8nF(6.3V) 7 C12 1uF (6.3V8 ) 9 J2 SWSPST 10 J3 SWSPST 11 12 AV DD R4 120k
48 47 46 45 44 43 42 41 40 39 38 37
U1 SD BIN N BIN P HF VDD R RIN LIN HF VDD L AG ND GA INO GA IN1 NC NC NC PVCCB PVCCB BOUTN BOUTN PGNDB PGNDB BOUTP BOUTP PVCCB PVCCB NC 36 35 34 33 32 31 30 29 28 AV DD 27 26 25
421DS
LIN R10 22k J4 C10 1nF (6.3V ) C30 1nF (6.3V )
R11 120k R2 330 R3 330 PV CC VR R1 0 C25 0.1uF(16V) + C17 10uF(16V ) PV CC C26 0.1uF(16V) + C19(optional) 1000uF(25V) PV CC D4 DIO DE(optional) L7 33uH L8 33uH R12 100 VC C 13 14 15 16 17 18 19 20 21 22 23 24
D3 DIO DE(optional)
C7 1uF ) (16V + C28 47uF(16V ) RO UT +
NC PVCCR PVCCR ROUT ROUT PGNDR PGNDL LOUT LOUT PVCCL PVCCL NC
NC NC NC AV CC NC NC AG ND VD DZ AV DD HF RC AG ND NC
VC C C24 0.1uF(16V) + C16 10uF(16V )
C13 1uF (6.3V ) C14 10uF(6.3V)
C8 1uF ) (16V C29 47uF(16V ) LO UT
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Preliminary
TMPA421DS
Rev.2.0 December 20, 2005
TERMINAL FUNCTIONS
TERMINAL HV/LV NAME AGND AVCC AVDD HFVDDB HFVDD HFRC LIN RIN ROUT LOUT PGNDR PGNDL PGNDB PVCCR PVCCL PVCCB BINP BINN BOUTN BOUTP SD GAIN0 GAIN1 VDDZ NC PIN NO 8,26,30 33 28 4 7 27 6 5 20,21 16,17 19 18 42,43 22,23 14,15 38,39,46,47 3 2 44,45 40,41 1 9 10 29 11,12,13,24, 25,31,32,34, 35, 36,37,48 No connection HV LV LV LV LV LV LV HV HV HV HV HV LV LV HV HV HV LV LV LV I O O O I I O O I I O O I I I O Analog ground High-voltage power supply (8V to 15V) 5-V voltage 2.5-V Reference for convenience of single-ended bass input 2.5-V Reference for convenience of right and left channel inputs Power up delay Left channel input Right channel input Class-D right channel output Class-D left channel output Power ground for right channel Power ground for left channel Power ground for bass Power supply for right channel Power supply for left channel Power supply for bass (8V to 15V) (8V to 15V) I/O DESCRIPTION
(8V to 15V)
Positive differential input for bass Negative differential input for bass Class-D negative output for bass Class-D positive output for bass Shutdown (Low valid) Gain0 control Gain1 control 5-V Regulated output (25mA output max.)
ABSOLUTE MAXIMUM RATINGS
Over operating free-air temperature range unless otherwise noted(1) In normal mode Supply voltage, PVCCR, PVCCL, AvCC In shutdown mode Input voltage, SD Input voltage, Gain0, Gain1, RIN, LIN, BINP, BINN Continuous total power dissipation Operating free-air temperature, TA Operating junction temperature, TJ Storage temperature, Tstg -0.3V to 18V -0.3V to 18V -0.3V to AVCC+0.3V -0.3V to 5V V V V V
See package dissipation ratings -20 to 85 C -20 to 150 -40 to 150 C C
(1) Stresses beyond those listed under"absolute maximum ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated under "recommended operating conditions "is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
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Preliminary
TMPA421DS
Rev.2.0 December 20, 2005
RECOMMENDED OPERATING CONDITIONS
MIN
Supply voltage, VCC High-level input voltage, VIH Low-level input voltage, VIL High-level input current, IIH Low-level input current, IIL Operating free-air temperature, TA PVCCB, PVCCR, PVCCL, AVCC SD , Gain0, Gain1 SD , Gain0, Gain1 VCC=15V, SD =15V VCC=15V, VCC=15V, Gain0=Gain1=5V Gain0=Gain1=0V -20 VCC=15V, SD =0V 8 2.0 0.8 100 5 0.5 0.5 85
MAX
15
UNIT
V V V uA uA C
PACKAGE DISSIPATION RATINGS
PACKGE TQFP48L(FD) DERATING FACTOR 33 mW/ C C TA 25 POWER RATING 4.125W TA = 70 C POWER RATING 2.64W TA = 85 C POWER RATING 2.15W
DC CHARACTERISTICS
T A=25 VCC=15V, RL=8 speaker (unless otherwise noted) C, PARAMETER
VOS VDD/AVDD HFVDD/HFVDDB fOSC ICC ICC(SD) rds(on)
TEST CONDITIONS
MIN
4.5
TYP
30 5.0 0.5x AVDD
MAX
5.5
UNIT
mV V
Output offset voltage for right/left channel LIN and RIN AC grounded IO=0 to25mA, SD =High, 5-V Regulated output VCC=8V to 15V Half VDD reference output Oscillator frequency No load
VCC=8-15V SD =High, VCC= 12V Quiescent current (no load) SD =High, VCC= 15V SD =0.8V, VCC= 12V Supply current in shutdown mode SD =0.8V, VCC= 15V High side Drain-source on-state resistance for all VCC=15V IO=1A, output Low side Gain0=High, Gain0=Low, Voltage Gain of bass at Vcc=15V Gain0=High, Gain0=Low, Gain0=High, Gain0=Low, Voltage Gain of bass at Vcc=12V Gain0=High, Gain0=Low, Gain0=High, Gain0=Low, Voltage Gain of bass at Vcc=9v Gain0=High, Gain0=Low, Gain0=High, Voltage Gain of right and left channel at Gain0=Low, Vcc=15V Gain0=High, Gain0=Low, Gain0=High, Voltage Gain of right and left channel at Gain0=Low, Vcc=12V Gain0=High, Gain0=Low, Voltage Gain of right and left channel at Gain0=High, Gain1= High Gain1=High Gain1= Low Gain1= Low Gain1= High Gain1=High Gain1= Low Gain1= Low Gain1= High Gain1=High Gain1= Low Gain1= Low Gain1= High Gain1=High Gain1= Low Gain1= Low Gain1= High Gain1=High Gain1= Low Gain1= Low Gain1= High
250 10 16 1 1 600 500 34 28 22 18 32 26 20 16 30 25 19 14 35 29 23 19 33 27 21 17 31
350 20 30
kHz mA uA m
dB
Gainb
dB
Gain
dB
dB
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Preliminary
TMPA421DS
Rev.2.0 December 20, 2005
Zi
Input resistance ofBINN/BINP/RIN/LIN
Gain0=Low, Gain0=High, Gain0=Low, Gain0=High, Gain0=Low, Gain0=High, Gain0=Low,
Gain1=High Gain1= Low Gain1= Low Gain1= High Gain1=High Gain1= Low Gain1= Low
25 19 15 15 30 60 100
k
AC CHARACTERISTICS
T A=25 VCC=15V, RL=8 speaker (unless otherwise noted) C, PARAMETER TEST CONDITIONS
15V RL=4 12V 9V 15V RL=6 *PO(max) Maximum continuous output power of bass (r.m.s) at 1kHz RL=8 12V 9V 15V 12V 9V 15V RL=16 12V 9V 15V RL=4 *PO(max) 12V 9V Maximum continuous output power of right/left channel (r.m.s) at 1kHz 15V RL=6 12V 9V 15V RL=8 Vn SNR Output noise Signal-to-noise ratio Maximum output at THD+N0.5, f=1kHz Gain0=Gain1=high, VCC=12V, PO(SE)=2W, RL=8 12V 9V
MIN
TYP
15 10 6.22 14.5 9.3 5.34 12.7 8 4.58 7.65 4.8 2.73 6 3.8 2.17 4.6 3.0 1.67 3.75 2.35 1.34 -70 85
MAX
UNIT
W
W
W
W
W
W
W dBV dB
Crosstalk Crosstalk SEBTL Thermal trip point Thermal hysteresis
-70 145 25
dB C C
For best performance, please refer to
http://www.taimec.com.tw/data/Tmpa421EVM/TMPA421DSEVM.pdf
for PCB layout.
*Important noticeMore copper area and vias are required for high output power especially when the total output power is higher than 15W.
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Preliminary
TMPA421DS
Rev.2.0 December 20, 2005
DETAILED DESCRIPTION Efficiency
The output transistors of a class D amplifier act as switches. The power loss is mainly due to the turn on resistance of the output transistors when driving current to the load. As the turn on resistance is so small that the power loss is small and the power efficiency is high. With 8 ohm load the power efficiency can be better than 80%.
PCB layout for power dissipation
No heat sink is necessary for power dissipation. However the PCB layout should be well designed to dissipate heat for high output power. With 80% power efficiency the generated heat when driving 15 watts to the 8 ohm load is about 3.75 watts. The heat can be carried out through the thermal pad of the device to the PCB. To ensure proper dissipation of heat the PCB has to have heat path from the bottom of the device which is soldered to the PCB. The area of the metal on the PCB for heat dissipation should be big enough. It is suggested that both sides of the PCB are used for power dissipation.
Shutdown
The shutdown mode reduces power consumption. A LOW at shutdown pin forces the device in shutdown mode and a HIGH forces the device in normal operating mode. Shutdown mode is useful for power saving when not in use. Internal circuit for shutdown is shown below.
Pop-less
A soft start capacitor can be added to the HFRC pin. This capacitor introduced delay for the circuit to be stable before driving the load. The set up time for internal circuit to be stable is quite fast, typically it is less than 100ms. Thus the pop noise caused by SDNB operation can be fixed easily. But for external circuitry the setup time depends on the component values used in the application.
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Preliminary
TMPA421DS
Rev.2.0 December 20, 2005
Class-D amplifier
+ 47uF + 13k 13k
PVCC
For single-ended outputs or right/left channels a build-in voltage divider is to provide half Vcc to the output pin as shown in the above diagram. During power up this divider is to pre-charge output capacitor to half Vcc before output signal is enabled to drive the speaker. Since the equivalent resistance of the voltage divider is 6.5k ohms (13kohms//13kohms) and the capacitance of the output coupling capacitor is 47uF the RC constant is 0.3 seconds. This indicates that the power up delay has to be much longer than 0.3 seconds. Normally a capacitor of 10uF at HFRC pin would provide 2.2 seconds start up delay to save power up pop noise. Above discussion assumes that the separation frequency is 500Hz and the speaker is 8 ohms. If the separation frequency is 200Hz and the speaker is 4 ohms instead then the output coupling capacitance would be changed to 200uF as calculated below. f =1 / (2 x 4 ohms x C) = 200 Hz C = 1 / (2x 4 ohms x 200 Hz ) = 200 uF In this case the RC constant of the charging circuit is 6.5 k ohms x 200uF = 1.3 seconds To save pop noise the start up delay time should be much longer than 1.3 seconds. A capacitance of 47 uF would provide 9.4 seconds delay. For frequency separation please refer to "Band pass filter for frequency separation of bass and R/L channels".
HFRC
HFRC provides a way of soft start up delay. A half_Vcc voltage detector is integrated to detect a RC charge up. The resistor of 320k ohms of the RC circuit is also integrated in the chip but the capacitor is externally hooked up. For C=10uF the half_Vcc delay is 1-e-t/RC=0.5 or e-t/RC=0.5
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Preliminary
TMPA421DS
Rev.2.0 December 20, 2005
that is t = - RC In0.5= 320k x 10u 0.693 = 2.2 seconds
The delay time changes linearly with capacitance at HFRC. So a 10uF capacitance will provide about 2.2 seconds delay.
Differential input VS single ended input
Differential input offers better noise immunity over single ended input. A differential input amplifier suppresses common noise and amplifies the difference voltage at the inputs. For single ended applications just tie the negative input end of the balanced input structure to ground. If external input resistors are used, the negative input has to be grounded with a series resistor of the same value as the positive input to reduce common noise.
Band pass filter for frequency separation of bass and R/L channels
For best sound effect the frequency of bass and R/L channels has to be separated. The bass channel amplifies the lower frequencies while the R/L channels amplify the higher frequencies. The power is saved not to drive bass speaker with high frequencies and not to drive R/L channel speakers with low frequencies. The noise level can be reduced as well. Typically the frequency boundary of bass and R/L channels is set 500 Hz and the output power of bass is set around 3~5 times of the R/L channels. Note that different applications may have different requirement for these values. Please refer to EVM documentation if the separation frequency is 200 Hz instead.
Bass channel filter
If the audio source is stereo (right channel signal and left channel signal) one can generate audio source for bass amplifier by mixing right and left signals and in the mean time filter out frequencies above 500 Hz. A typical application is shown below. Note that Zin=15k ohms is the internal resistance of the class-D amplifier when gain0=gain1=High.
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Preliminary
TMPA421DS
Rev.2.0 December 20, 2005
Rin Lin
R1 12k R1 12k Cin 0.47uF //12k (R1)/2 12k C1 37nF Cin 0.47uF Zin 15k
Class-D amplifier Zin 15k
The -3db frequency at high frequency corner is f-3db = 1/ (2R C) where R=2(Zin // (R1)/2) and C=C1. With specified values f-3db = 500Hz. The -3db frequency at low frequency corner is calculated as f-3db = 1/ (2R C) where R=Zin + (R1)/2 and C=Cin. With specified values f-3db = 16Hz.
Right and Left channel filters
To block frequencies below 500Hz, a typical application is shown below.
Rin
R1
22k
C1 C2 8.6nF 0.9nF C1 C2 8.6nF 0.9nF Zin 15k
Class-Damplifier Zin 15k
Lin
R1 22k
The -3db frequency at low frequency corner is f-3db = 1/ (2R C) where R=Zin + R1 and C=C1. With specified values f-3db = 500Hz. The -3db frequency at high frequency corner is f-3db = 1/ (2R C) where R=Zin // R1 C=C2. With specified values f-3db = 20kHz. Note that if gain0 and gain1 are set at different states the internal input resistance is changed accordingly. Please refer to DC CHARACTERISTICS for detail. As such the filters should be redesigned to meet the 500 Hz frequency boundary.
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Preliminary
TMPA421DS
Rev.2.0 December 20, 2005
Voltage gain
The voltage gain can be set through gain0/gain1 control or by external input resistors connecting to input pins. If external resistors are used for BINP and BINN of bass channel then these input resistors should be well matched. Well matched resistors are also required even for single ended input configuration for low noise. Suppose the external input resistors Rext are used then the voltage gain is roughly Av=750k ohm / (Rext+15k ohm) for gain0=gain1=High Where 15k ohm is the internal resistance of the input pins. For other gain0/gain1 states please refer to DC CHARACTERISTICS for different input resistance.
Power ratio of bass channel and right/left channels
The output power ratio of bass to R/L channels is normally set 3~5. However different music has different stress in different frequency range. It becomes difficult to define a fix voltage gain for different applications and to maintain the requirement of bass to R/L ratio. A convenient way of controlling the ratio is to make bass adjustable relative to R/L channels. An easier way is to use VR as shown below.
Rin VR R1 12k
Lin VR R1 12k Cin BINP 0.47uF Zin
Cin 6k
BINN Zin Bass amplifier
0.47uF
Another way is to use frequency synthesizer to preset voltage gain for different frequency range for particular music content. For simply applications an example is given below to show 3X ratio between bass output power and R/L output power. For Vcc=15v and 8ohm load the voltage gain of the bass channel is around 32. If the power ratio is 3 then the voltage ratio is
3 =1.732 and the gain of the R/L channel is 18.5. The voltage gain of the R/L channels is roughly defined as
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Preliminary
TMPA421DS
Rev.2.0 December 20, 2005
(750k ohms)/(Ri+15k ohms) resulting Ri= 25.5k ohms. To meet the -3db frequency of the R/L channels which is 500Hz, the filter capacitance should be adjusted to C= 1/(2 x (25.5k+15k ohms) x 500Hz) = 7.86nF. For higher output power one can consider to use 4 ohm speaker for bass and 8 ohm speakers for R/L channels. Suppose the power ratio is set 5X, then the voltage ratio is
5 / 2 =1.58. For Vcc=15v and 4ohm load the voltage gain of the bass channel is around 30. Thus the gain of the R/L channel is 19. The voltage gain of the R/L channels is defined as (750k ohms)/(Ri+15k ohms) resulting Ri= 24.5kohms .
To meet the -3db frequency of the R/L channels which is 500Hz, the filter capacitance should be adjusted to C= 1/(2 x (24.5+15k ohms) x 500) = 8nF. Note that the formula for voltage gain varies with supply voltage and loading. But the procedure is to find out the value of Ri before the capacitance is determined.
Output coupling capacitor
The speaker of the bass channel is tied as BTL. There is no need to have an output capacitor at the output end. But for right and left channels coupling capacitors are required to block DC from the speakers. Since the right and left channels do not amplify frequencies below 500Hz the output coupling capacitance does not have to be big. One can choose the -3db frequency of the output coupling stage to be 200Hz, not too high to attenuate voltage at 500Hz, then the coupling capacitance is C= 1/(2x 8 ohm x 200Hz) =100uF for 8 ohm load. or C= 1/(2x 4 ohm x 200Hz) =200uF for 4 ohm load.
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Preliminary
TMPA421DS
Rev.2.0 December 20, 2005
Input filter
In case band pass filter for frequency separation of bass and R/L channels is not used, the AC coupling capacitors are still required to block the DC voltage from the device. They also define the -3db frequency at the low frequency side. The -3db frequency of the low frequency side is f-3db = 1/ (2R C) where C is the AC coupling capacitance and R is the total resistance in series with C. Note that R=Zin(internal resistance) + Rext(external resistance) Also note that the input resistance of BINN/BINP/LIN/RIN is 15K ohms at Gain0=Gain1=high. Please refer to DC CHARACTERISTICS for detail.
Output filter
Ferrite bead filter can be used for EMI purpose. The ferrite filter reduces EMI around 1 MHz and higher FCC and CE only test radiated emissions greater than 30 MHz When selecting a . ferrite bead, choose one with high impedance at high frequencies, but low impedance at low frequencies. Use an LC output filter if there are low frequency 1 MHz EMI sensitive circuits and/or there are long wires from the amplifier to the speaker. EMI is also affected by PCB layout and the placement of the surrounding components. For BTL output the suggested LC values for different speaker impendence are showed in following figures.
LC Output Filter, Speaker Impedance= 4
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Preliminary
TMPA421DS
Rev.2.0 December 20, 2005
LC Output Filter, Speaker Impedance=6 & 8
15H Vo+ 0.22 F 15H Vo0.22 F 1 F
LC Output Filter, Speaker Impedance=4
33H Vo+ 0.47 F 33H Vo0.1 F 0.1 F
LC Output Filter, Speaker Impedance=6 & 8
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Preliminary
TMPA421DS
Rev.2.0 December 20, 2005
Ferrite Chip Bead Vo+ Ferrite Chip Bead Vo100pF 100pF
Typical Ferrite Chip Bead Filter Chip bead example KML2012Q102N 1kohms@100MHz, DCR=0.2ohms, I=1A For single-ended output the suggested LC values for different speaker impendence are showed in following figures.
LC Output Filter, Speaker Impedance= 4
LC Output Filter, Speaker Impedance= 6 & 8
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Preliminary
TMPA421DS
Rev.2.0 December 20, 2005
Typical Ferrite Chip Bead Filter Chip bead example KML2012Q102N 1kohms@100MHz, DCR=0.2ohms, I=1A
EARPHONE USE
Class-D output can be used to drive earphone. However to avoid high power to overdrive earphone and to prevent human ear to accidentally be hurt by loud noise, a resistor has to be put in series with the earphone speaker. Typically a resistor of 330 ohms is adequate for this purpose.
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Tai-1 Microelectronics
www.taimec.com.tw / www.class-d.com.tw
Preliminary
TMPA421DS
Rev.2.0 December 20, 2005
Over temperature protection
A temperature sensor is built in the device to detect the temperature inside the device. When a high temperature around 145oC and above is detected the switching output signals are disabled to protect the device from over temperature. Automatic recovery circuit enables the device to come back to normal operation when the internal temperature of the device is below around 120oC.
Over current protection
A current detection circuit is built in the device to detect the switching current of the output stages of the device. It disables the device when a pulse current beyond 8 amps is detected. It protects the device when there is an accident short between outputs or between output and power/gnd pins. It also protects the device when an abnormal low impedance is tied to the output. High current beyond the specification may potentially causes electron migration and permanently damage the device. Shutdown or power down is necessary to resolve the protection situation. There is no automatic recovery from over current protection.
Copyright (c)2005,Tai-1 Microelectronics Corp.
18
PDF created with pdfFactory trial version www.pdffactory.com
Tai-1 Microelectronics
www.taimec.com.tw / www.class-d.com.tw
Preliminary
TMPA421DS
Rev.2.0 December 20, 2005
Physical Dimensions
( IN MILLIMETERS)
SYMBOLS A A1 A2 b C D1 D E1 E e L L1 ccc
MIN. 0.00 0.95 0.17 0.09 6.90 8.80 6.90 8.80 0.45 -
NDM. 1.00 0.22 7.00 9.00 7.00 9.00 0.50(TYP) 0.60 1.00(REF) -
MAX. 1.15 0.10 1.05 0.27 0.20 7.10 9.20 7.10 9.20 0.75 0.08
TQFP48
Copyright (c)2005,Tai-1 Microelectronics Corp.
19
PDF created with pdfFactory trial version www.pdffactory.com
Tai-1 Microelectronics
www.taimec.com.tw / www.class-d.com.tw
Preliminary
TMPA421DS
Rev.2.0 December 20, 2005
IMPORTANT NOTICE
Tai-1 Microelectronics Corp. reserves the right to make changes to its products and services and to discontinue any product or service without notice. Customers should obtain the latest relevant information for reference. Testing and quality control techniques are used to screen the parameters. Testing of all parameters of each product is not necessarily performed.
Tai-1 Microelectronics Corp. assumes no liability for applications assistance or customer product design. To minimize the risks associated with customer products and applications, customers should provide adequate design and operating safeguards.
Reproduction of information in data sheets or related documentation is permissible only if reproduction is without alteration and is accompanied by all associated warranties, conditions, limitations, and notices. Tai-1 Microelectronics Corp. is not responsible or liable for such altered documentation.
Resale of Tai-1 Microelectronics Corp. products or services with statements different from the parameters stated by Tai-1 Microelectronics Corp. for that product or service voids all express and any implied warranties. Tai-1 Microelectronics Corp. is not responsible or liable for any such statements.
Copyright (c)2005,Tai-1 Microelectronics Corp.
Copyright (c)2005,Tai-1 Microelectronics Corp.
20
PDF created with pdfFactory trial version www.pdffactory.com

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