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1/19 tda7476 april 2001 n wide operating voltage range n st-by function (c-mos) n low quiescent st-by current consumption n i 2 c bus interface with 2 externally selectable addresses n up to 5 btl equivalent inputs for fault detection in the audio channels - short to gnd - short to vs - short across the load (at turn-on) - open load (at turn-on) n 2 aux inputs for fault detection in the antenna and boosters supply line- short to gnd- open load n warning pin function (interrupt facility) activated in the following condition: - audio channel shorted to v s - audio channel shorted to gnd - aux input shorted to gnd n noise free diagnostics operation n protectors n load dump voltage n open gnd n reversed battery n esd description the car radio diagnostic processor is an interface chip in bcd technology intended for car radio appli- cations. it is able to detect potential faults coming from any misconnection in the car radio or in the har- ness when installing the set. the device is able to reveal any fault in the loud- speaker lines and in the antenna and booster supply lines, providing a proper output signal (i2c bus com- patible) in order to disable the ics under fault and/or to alert the micro-controller by means of warning messages. so-24 ordering number: tda7476 car radio diagnostic processor pin connection (top view ) gnd sda scl add w aux1 in aux1 out aux2 in aux2 out ch1- ch2- ch2+ ch3- ch3+ ch4- ch4+ ch5+ ch5- 1 3 2 4 5 6 7 8 9 22 21 20 19 18 16 17 15 23 10 24 5v ch1+ d97au570a st-by t-cap 11 14 13 12 v s csr multipower bcd technology
tda7476 2/19 block diagram & application circuit pin function n pin description 1 gnd ground 2 sda dta line 3 scl clock line 4 add address select 5 w warning 6 aux1 out aux1 output 7 aux1 in aux1 input 8 aux2 in aux2 input 9 aux2 out aux2 output 10 5v 5v-regulator 11 st-by stand-by 12 v s supply voltage 13 csr current setting resistor 14 t-cap timing capacitor 15/16 ch1+/ch1- audio output - channel 1 17/18 ch2-/ch2+ audio output - channel 2 19/20 ch3+/ch3- audio output - channel 3 21/22 ch4-/ch4+ audio output - channel 4 23/24 ch5+/ch5- audio output - channel 5 i 2 c interface add dig-gnd scl sda aux1 aux2 rsens1 rsens2 d96au499a ch5 ch4 ch3 ch2 ch1 current forcing & comparators delay voltage regulator & test signal generator out in in out r cs c t w st-by sw1 c2 100nf 5v ref v s 12 2 3 4 5 11 10 14 13 19 8 7 6 15 16 17 18 19 20 21 22 23 24 c3 10 m f r3 10k w r4 10k w r5 51 w c1 10 f
3/19 tda7476 absolute maximum ratings (*) minimum value between v s +10v and 25v. thermal data symbol parameter value unit v op operating supply voltage 18 v v s dc supply voltage 28 v v peak peak supply voltage t = 50ms 40 v p tot total power dissipation tcase = 25c 1.5 w t stg ; tc- storage and junction temperature -40 to 150 c v sb stand-by pin voltage 6 v v sda sda pin voltage 6 v v scl scl pin voltage 6 v v add add pin voltage 6 v v ch ch+ or ch- pin voltage min (*) (v s +10, 25) symbol parameter value unit r th j-amb thermal resistance junction to ambient max. 85 c/w electrical characteristics (v s = 14.4v; t amb = 25, unless otherwise specified.) symbol parameter test condition min. typ. max. unit v sb in stand-by in threshold 1.5 v v sb out stand-by out threshold 3.5 v i sb stand-by current consumption stand-by voltage pin = 1.5v 100 m a i q total quiescent current total quiescent current with tda7476 not addressed 5ma audio inputs ch1, ch2, ch3, ch4, ch5 - turn on diagnostic pgnd short to gnd det. (below this limit, the audio output is considerd in short circuit to gnd) power amplifier in st-by condition 0.8 v pvs short to vs det. (above this limit, the audio output is considered in short circuit to vs) vs-0.6 v pnop normal operation thresholds. (within these limits, the audio output is considered without faults) 1.2 vs-1.2 v
tda7476 4/19 lsc shorted load det. (voltage across the audio outputs). below this limit the load is considered shorted. power amplifier in st-by condition 5 mv lop open load det. (voltage across the audio outputs). above this limit the load is considered open. 550 mv lnop normal load det. (voltage across the audio output). within these limits the load resistance is considered normal. 22 220 mv aux inputs aux1, aux2 - turn on diagnostic agnd short to gnd det. (voltage across the sensing resistor). above this limit the aux pin is considered in short circuit to gnd. high side driver on 0.85 v aol open load det. (voltage across the sensing resistor). below this limit the aux pin is considered in open load condition. 0.085 v anop normal operation det. (voltage across the sensing resistor). within these limits the load resistance connected to the aux pin is considered correct. 0.125 0.5 v audio inputs - permanent diagnostic pgnd short to gnd det. (below this limit, the audio output is considered in short circuit to vs) this condition must be true for a time higher than tdel power amplifier on 0.8 v pvs short to vs det. (above this limit the audio output is considered in short circuit to vs) this condition must be true for a time higher than tdel vs-0.6 v pnop normal operation thresholds. (within these limits, the audio output is considered without faults) 1.2 vs-1.2 v aux inputs - permanent diagnostic agnd short to gnd det. (above this limit, the audio output is considered in short circuit to vs) this condition must be true for a time higher than tdel high side driver on 0.85 v electrical characteristics (continued) (v s = 14.4v; t amb = 25, unless otherwise specified.) symbol parameter test condition min. typ. max. unit
5/19 tda7476 aol open load det. (voltage across the sensing resistor. below this limit the aux pin is considered in open load condition)this condition must be true for a time higher than tdel high side driver on 0.085 v anop normal operation det. (voltage across the sensing resistor. within these limits the load resistance connected to the aux pin is considered correct) 0.125 0.5 v permanent diagnostic - acquisition time delay tdel acquisition time delay - the fault is considered true if the fault condition are present for more than tdel without interruption 2s permanent diagnostic - warning pin v sat saturation voltage on pin 5 sink current at pin 5 = 1ma 1 v address select v add voltage on pin 4 address 0100010x 1.5 v address 0100011x 3 5 v i 2 c bus interface f scl clock frequency 400 khz v il input low voltage 1.5 v v ih input high voltage 3 v v sat sat voltage at pin 2 sink current at pin 2 = 5ma 1.5 v electrical characteristics (continued) (v s = 14.4v; t amb = 25, unless otherwise specified.) symbol parameter test condition min. typ. max. unit working principles turn-on diagnostic - ch1, ch2, ch3, ch4, ch5 - shorted load/open load detection n to detect a short across the load or an open load, a subsonic current pulse is generated. the information related to the status of the outputs is measured and memorized at the top of the current pulse (tm in fig.1). the current is sourced by the positive pins (ch1+,...ch5+) and it is sunk by the corresponding negative pins (ch1-,...ch5-). figure 1. t m t s t (ms) i source i sink i(ma) d97au571
tda7476 6/19 n isink and isource are depending on the external resistor rcs . the minimum allowed value for rcs is 1.65kohm. the relationship among isink, isource and rcs is the following: isink = (3.3/rcs) 11 isource = 1.5 isink n on bridge (or bridge equivalent) devices if there is no short circuit to gnd or to vs, isource goes into saturation mode (for vout > 3v), and in the load flows isink. as the turn-on diagnostic thresholds are fixed, it is possible to calculate the ranges of loudspeaker resistance in which short circuit (s.c.), normal operation and open load are detected as following: where l sc , l nop , l op as specified in the elctrical characteristics. for example, here below are two cases, with rcs = 3.3kohm and rcs = 1.8kohm.. the exact values of the above mentioned resistive ranges may vary a little, depending on the power amplifier used. turn-on diagnostic - ch1, ch2, ch3, ch4, ch5 - short to gnd and vs . to detect if there is short circuit to gnd or vs, the subsonic current pulse is exploited. the information related to the status of the outputs are measured and memorized at the top of the current pulse (tm in fig.1). if no faults are present, the pins connected to the audio outputs (ch1,..ch5) will reach about 3v.if one or more outputs are shorted to gnd, these voltages become lower than 3v.if one or more outputs are shorted to vs, the output volt- age increases over 3v.the fault status can be know by sensing the output voltages. the reason way voltage threshold has been preferred instead of a current threshold to declare short circuit resistor ranges is two fold: s.c. across load x open load 0 w r 2 r 3 infinite x normal load r 1 r 4 d01au1256 r1 l sc,max i k sin ------------------- l sc,max 36.3 ------------------- r cs == r2 l nop,min i k sin --------------------- - l nop,min 36.3 --------------------- - r cs == r3 l nop,max i k sin ---------------------- - l nop,max 36.3 ---------------------- - r cs == r3 l op,max i k sin ------------------- - l op min , 36.3 ------------------- - r cs == s.c. across load x open load 0 w 1.1 w 11 w infinite x normal operation 0.24 w 27 w d96au500a s.c. across load x open load 0 w 2 w 20 w infinite x normal operation 0.45 w 50 w
7/19 tda7476 1) the amplifier can drain current in the resistive path of the short circuit, hence this current and consequently the short circuit resistor cannot be determined with a sufficient level of accuracy. 2) the voltage difference between the car radio ground (reference) and the position of the chassis of the car where the loudspeaker line is connected (due to an accidental short circuit) can be up to some hundreds of mv. this does not permit a correct measure of the short circuit resistor. turn-on diagnostic - aux1, aux2 to detect if there is a short circuit to gnd or an open load involving to the aux output of the car radio, the volt- age across a sensing resistor rsens is detected.these output voltages (for example for the active antenna and for the booster) are usually generated by high side drivers, but also voltage regulators with vout >5v are admis- sible. the detection ranges can be set by adjusting the sensing resistors rsens1 or rsens2 as following: where a ol , anop, agnd are as specified in the electrical characteristics. for example, if rsens = 5 ohm, the following detection table will be operative : permanent diagnostic - ch1, ch2, ch3, ch4, ch5 - short to gnd and vs during the car-radio normal operation, to detect a short circuit to gnd (or to vs), the output voltages are sensed. if one or more outputs stay at any voltage below 0.8v or over vs-0.6v for more than 2 sec. (typ), the warning pin is pulled down.the m p can address the tda7476 to know the status.the subsonic current pulse is activated also in this case. the fault is correctly detected if it remains until the memorization (tm in fig.1).in this phase, faults regarding shorts across the load and open loads cannot be detected. s.c. to gnd x open load i 2 i 3 x normal operation i 1 i 4 d01au1258 i 4 a ol,ma x r sens -------------------- - - = i 3 a nop,min r sens ---------------------- = i 2 a nop,max r sens ----------------------- - = i 1 a gnd,min r sens ---------------------- = open load x s.c. to gnd 100ma 25ma x normal operation 170ma 17ma d96au50 3
tda7476 8/19 permanent diagnostic - aux1, aux2 - short circuit to gnd and open load n the detection mode of the auxiliary inputs is equal to what is in place during turn-on, but the fault must be lasting without interruption for more than 2 seconds.the warning pin is pulled down only in case of short to gnd. this is to avoid that this pin remains permanently to 0 level if one or both aux outputs of the car radio are unused. timing n from the byte "add1" to the byte "add2" the mp must wait a period twait1(see software specification) that is depending on the timing capacitor ct according to the following table (twait1> tm, max): note: any (positive) spread of the capacitor value must be added. the relation to be used to determine twait1 from the value of ct according to the following: twait1 > tm, max = (130 ct/10 m f)ms n after the byte "add2" the power amplifier can be switched-on. in some cases, the m p has to wait until the current pulse is finished (twait2). this time (ts in fig.1) is given by: twait2 > ts, max = (140 ct/10 m f)ms for bridge or bridge equivalent devices (figg.5,6), ct = 10 m f will be enough. turn-on diagnostic - thresholds ch1, ch2, ch3, ch4, ch5 n output voltage during test. (the power amplifier must be in st-by mode). n voltage across the load during test. (the power amplifier must be in st-by mode). n note: some faults can mask others if they are present at the same moment on the same channel: - if there is a short to gnd and an open load on the same channel, the tda7476 gives information only about one of them, depending on the wire on which the short circuit is present. - the short circuit to gnd masks any short circuit across the load. - the short circuit to vs masks any short or open load. ct ( m f) tm max (ms) 3.3 45 4.7 65 10 130 22 290 47 620 100 1300 d96au502b s.c. to gnd x s.c. to vs 0v 1.2v v s -1.2 v s x normal operation 0.8v v s -0.6v s.c. across load x open load 0v 22mv 220mv v s x normal operation 5mv 550mv d97au631a
9/19 tda7476 the following table shows the result pointed out by tda7476 when multiple misconnections are present: (*) ch means ch+ or ch- aux1 - aux2 n voltage across the sensing resistors n the minimum voltage of the aux in pin to sense the open load condition is 2v. n the minimum voltage of the aux in pin to detect the short circuit to gnd, by sensing the drop on the resistors is 4.5v. if this voltage falls below 2v, the aux in is considered short circuited to gnd. from 2v to 4.5v the sensing circuit can detect a short circuit in both ways (by sensing across the resistor or through the voltage between the aux in pin and gnd). permanent diagnostic - thresholds ch1, ch2, ch3, ch4, ch5 n the circuit will recognize as a fault condition any situation where the following short circuit voltages last more than 2 sec (typ). n output voltage aux1 - aux2 n the voltage across the resistors rsens1 or rsens2 is sensed. the circuit will recognize as a fault condition any situation where the following voltages last more than 2sec (typ) in the region "s.c.to gnd" or "open load". actual faults pointed out fault s.c. ch+ to gnd + open load s.c. to gnd s.c. ch(*) to gnd + s.c. across load s.c. to gnd s.c. ch- to gnd + open load open load s.c. ch(*) to v s + open load s.c. to v s s.c. ch(*) to v s + s.c. across load s.c. to v s s.c. ch+ to v s + s.c. ch- to gnd s.c. to v s s.c. ch- to v s + s.c. ch+ to gnd s.c. to gnd + s.c. to v s s.c. to gnd x open load v s 0.5v 125mv 0v x normal operation 0.85v 85mv d97au572a s.c. to gnd x s.c. to vs 0v 1.2v v s -1.2 v s x normal operation 0.8v v s -0.6v d97au573b s.c. to gnd x open load v s 0.5v 125mv 0v x normal operation 0.85v 85mv d97au574a
tda7476 10/19 n the minimum voltage of the aux in pins to sense the open load condition is 2v. n the minimum voltage of the aux in pin to detect the short circuit to gnd by sensing drop on the resistor is 4.5v. if this voltage is below 2v, the aux line is considered short circuited to gnd. from 2v to 4.5v the sensing circuit can detect a short circuit in both ways (by sensing across the resistor or through the voltage between the aux in pin and gnd). i 2 c bus interface data transmission from microprocessor to the tda7476 and viceversa takes place through the 2 wires i 2 c bus interface, consisting of the two lines sda and scl (pull-up resistors to positive supply voltage must be connected). data validity as shown by fig. 2, the data on the sda line must be stable during the high period of the clock. the high and low state of the data line can only change when the clock signal on the scl line is low. start and stop conditions as shown by fig. 3 a start condition is a high to low transition of the sda line while scl is high. the stop condition is a low to high transition of the sda line while scl is high. byte format every byte transferred to the sda line must contain 8 bits. each byte must be followed by an acknowledge bit. the msb is transferred first. acknowledge the transmitter* puts a resistive high level on the sda line during the acknowledge clock pulse (see fig.4). the receiver** the acknowledges has to pull-down (low) the sda line during the acknowledge clock pulse, so that the sdaline is stable low during this clock pulse. * transmitter = master ( m p) when it writes an address to the tda7476 = slave (tda7476) when the m p reads a data byte from tda7476 ** receiver = slave (tda7476) when the m p writes an address to the tda7476 = master ( m p) when it reads a data byte from tda7476 figure 2. data validity on the i 2 cbus sda scl data line stable, data valid change data allowed d99au1031
11/19 tda7476 figure 3. timing diagram on the i 2 cbus figure 4. acknowledge on the i 2 cbus software specifications the tda7476 is activated by turning-on the st-by pin (cmos compatible). in this condition it waits for the i2cbus addressing byte add1 (write to tda7476) this sequence (where the bit 0 of add1 is at 0 level) enables the acquisition routine and starts the single pulse (containing infrasonic harmonics) for the test. during this period the data regarding all the outputs are memo- rized.after a period twait1 that depends on the value of the timing capacitor (see timing ) the m p redirects the tda7476 by the byte add2 . the byte add2 contains the bit 0 at 1 level. this enables the reading mode, tda7476's. the 3 bytes with the diagnostic information byte1, byte2, byte3 (read from tda7476) are now transmitted to the m p. the address of tda7476 is selected using pin add (pin 4) . if add is connected to ground, then a = 0 and the tda7476 address is 0100010x. if add is connected to 5v, than a = 1 and the tda7476 address is 0100011x n the tda7476 provides two types of diagnostic information: a) turn-on diagnostic - the first time that the tda7476 is addressed by i 2 cbus, the more complete set of diagnostic information is activated: - ch1, ch2, ch3, ch4, ch5 short circuit to gnd short circuit to vs open load (*) short circuit across the load (*) (*) detected if the power amplifiers are in st-by condition. - aux1, aux2 short circuit to gnd (*) open load (*) (*) detected if the high side drivers attached to the aux outputs are on. here following the turn-on diagnostic output bytes add1 s 010001a 0 ack stop add1 s 010001a 0 ack byte1 ack byte2 ack byte3 ack stop scl sda start i 2 cbus stop d99au1032 scl 1 msb 23789 sda start acknowledgment from receiver d99au1033
tda7476 12/19 read byte 1 read byte 2 read byte 3 when the m p reads correctly all the 3 bytes containing the mentioned information and gives the last acknowl- edge, the tda7476 switches to the "permanent diagnostic operation" b) permanent diagnostic it can sense the following diagnostic information: ch1, ch2, ch3, ch4, ch5 - short circuit to gnd - short circuit to vs aux1, aux2 - short circuit to gnd (*) - open load (*) (*) detected if the high side drivers attached to the aux outputs are on. in this case the above conditions are not detected while the single infrasonic current pulse is present but be- fore. the fault condition must be present for more than 2sec. (typ) and must be also true during the pulse, where the data are memorized and then transmitted.the bytes from/to m p and tda7476 are the same as those in case of turn-on diagnostic (see above). here following is the permanent diagnostic output data bytes. the bits d7 and d6 of the first byte both stand at 0 level. this condition, although not possible during the turn-on diagnostic, can be useful to confirm that the bytes are referred to the permanent diagnostic. msb lsb stat us d7 d6 d5 d4 d3 d2 d1 d0 x x x x 1 1 x 0 ch1 short circuit to vs x x x x 1 1 0 x ch1 short circuit to gnd x x x x 1 0 1 1 ch1 open load x x x x 0 1 1 1 ch1 short circuit across the load 1 1 x 0 x x x x ch2 short circuit to vs 1 1 0 x x x x x ch2 short circuit to gnd 1 0 1 1 x x x x ch2 open load 0 1 1 1 x x x x ch2 short circuit across the load x x x x 1 1 x 0 ch3 short circuit to vs x x x x 1 1 0 x ch3 short circuit to gnd x x x x 1 0 1 1 ch3 open load x x x x 0 1 1 1 ch3 short circuit across the load 1 1 x 0 x x x x ch4 short circuit to vs 1 1 0 x x x x x ch4 short circuit to gnd 1 0 1 1 x x x x ch4 open load 0 1 1 1 x x x x ch4 short circuit across the load x x x x x x 1 0 aux1 short circuit to gnd x x x x x x 0 1 aux1 open load x x x x 1 0 x x aux2 short circuit to gnd x x x x 0 1 x x aux2 open load 1 1 x 0 x x x x ch5 short circuit to vs 1 1 0 x x x x x ch5 short circuit to gnd 1 0 1 1 x x x x ch5 open load 0 1 1 1 x x x x ch5 short circuit across the load
13/19 tda7476 read byte 1 read byte 2 read byte 3 repetitive turn-on diagnostic during the turn-on diagnostic, the tda7476 can reveal false "short circuit across load" and/or false "open load" due to noise sources such as door slams. this problem can be solved doing more than one turn-on diagnostic routine. if the m p asks for n times the state of the audio system, it has to consider a fault as really present only if it is detected in all the n turn-on diagnos- tic.as above explained, the first time the tda7476 receivers the byte add1, it does the turn-on diagnostic; then each time it is addessed with add1, it does the permanent diagnostic. this is not true if, when the m p sends for the first time the byte add2, it does not send to the tda7476 the acknowledge after it has received the byte byte3. in this case, the tda7476 does not switch from turn-on to permanent diagnostic mode so if it receives again the byte add1 it works as it was the first time that it does the turn-on diagnostic. in order to do repetitive turn-on diagnostic, the mp has to be programmed as following: n step 1: the m p sends add1 n step 2: the m p waits twait1 seconds n step 3: the m p sends add2, receives byte1 , byte2 , byte3 , does not send the acknowlegde after byte3 msb lsb stat us d7 d6 d5 d4 d3 d2 d1 d0 0 0 x x 1 1 x 0 ch1 short circuit to vs 0 0 x x 1 1 0 x ch1 short circuit to gnd 00xx1111 00xx1111 0 0 x 0 1 1 x x ch2 short circuit to vs 0 0 0 x 1 1 x x ch2 short circuit to gnd 001111xx 001111xx 1 1 x x 1 1 x 0 ch3 short circuit to vs 1 1 x x 1 1 0 x ch3 short circuit to gnd 11xx1111 11xx1111 1 1 x 0 1 1 x x ch4 short circuit to vs 1 1 0 x 1 1 x x ch4 short circuit to gnd 111111xx 111111xx 1 1 x x x x 1 0 aux1 short circuit to gnd 1 1 x x x x 0 1 aux1 open load 1 1 x x 1 0 x x aux2 short circuit to gnd 1 1 x x 0 1 x x aux2 open load 1 1 x 0 x x x x ch5 short circuit to vs 1 1 0 x x x x x ch5 short circuit to gnd 1111xxxx 1111xxxx start add1 ack ack
tda7476 14/19 n step 4: repeat step1, step2, step3 while the second, third, fourth, ...turn-on diagnostic has to be done. during the last turn-on diagnostic the m p sends add2, receives byte1 , byte2 , byte3 , and sends the acknowlegde after byte3 in this way only after that the tda7476 has done for n times the turn-on diagnostic, it switches from turn-on to permanent diagnostic mode.from now the tda7476 always does the permanent diagnostic.to save time when the audio system is switched on, it is possible to do the repetitive turn-on diagnostic when the car-radio is turned off. in this case the steps to follow to do the repetitive turn-on diagnostic are the following: 1- to switch off the tda7476 connecting stby pin to ground; 2- to wait t 5v seconds (time necessary for the discharge of the capacitor). if c 5v = 10 m f then t 5v = 20ms typ; 3- to switch on the tda7476 4- to do the repetitive turn-on diagnostic as above described; 5- to turn off the tda7476. warning pin n this is an open drain output pin that is activated when a fault condition is present for more than 2 sec (typ). the fault conditions related to the warning pin are as follows: - aux1, aux2 short to gnd - ch1, ch2, ch3, ch4, ch5: short circuit to gnd short circuit to vs n the purpose of this pin is to alert the m p and start with the permanent diagnostic routine only if faults are present, thus avoiding cpu's waste of time. start add2 ack byte1 ack byte2 ack byte3 stop start add2 ack byte1 ack byte2 ack byte3 ack stop
15/19 tda7476 application notes n when single-ended devices are used and the application circuit is as shown in fig. 7,8, it is necessary to use: - a greater timing capacitor so that the time tm is high and the outputs of the amplifiers are able to rise over 1v ; - a resistor r cs 1.5 times higher than that used for the bridge amplifiers. in this case, the loudspeaker resistance ranges in which short circuit, normal operation and open load are detected will be as follows: for example, here below are two cases, with r cs = 4.7kohm and r cs = 2.7kohm. the exact values of the above mentioned resistive ranges may vary a little, depending on the power amplifier used in permanent mode for single-ended devices as in fig. 7, 8 a short citcuit to ground is detected both when a short to ground is really present and when the load is missing. on single-ended devices as in figure 6, 8 if the loads are present then both in turn-on and in permanent diag- nostic the fault present on one channel is pointed out for all the loads connected together.for example: - see fig.8 if ch1+ is shorted to ground, the tda7476 reveals a short to ground both for ch2 and for ch1. - see fig.6 if ch1+ is shorted to ground, the tda7476 detects a short circuit to ground for ch1, ch2, ch3, ch4. about timing for the tda7375, connected as in fig.7, ct = 47 m f if cout = 1000 m f, and ct = 100 m f if cout = 2200 m f. if the circuit is as shown by fig. 8, the suggested values of ct are as follows: ct = 22 m f if cout = 1000 m f, ct = 47 m f if cout = 2200 m f. s.c. across load x open load r 2,se r 3,se x normal operation r 1,se r 4,se d01au1257 r1,se l sc,max i source --------------------- l sc,max 54.45 --------------------- r cs == r2,se l sc,min i source ------------------- - l nop,min 54.45 --------------------- - r cs == r3,se l nop,max i source ---------------------- - l nop,max 54.45 ---------------------- - r cs == r4,se l op,min i source ------------------ l op,min 54.45 ------------------ r cs == s.c. across load x open load 0 w 1.9 w 19 w infinite x normal operation 0.43 w 47 w d96au501a s.c. across load x open load 0 w 1.1 w 11 w infinite x normal operation 0.24 w 27 w
tda7476 16/19 n to use the tda7476 with a car-radio system which has less than five audio channel and less than two auxiliary loads, it is necessary to take some cares: - each pin ch not used has to be fixed to 5v - each pin aux1in, aux1out, auxin2, aux2out not used has to be fixed to a voltage equal or greater than 5v the 5v voltage reference available on the chip (pin 10) is very useful to fix both ch and aux pins to 5v. application examples with st audio power ics figure 5. quad bridge amplifiers figure 6. tda7451 tda7384, tda7385, tda7386, tda7454 +- -+ +- -+ ch1+ ch2+ ch3+ ch4+ ch5+ ch5- ch4- ch3- ch2- ch1- tda7476 d97au578a r tda7451 +- -+ +- -+ ch1+ ch2+ ch3+ ch4+ ch5+ ch5- ch4- ch3- ch2- ch1- tda7476 d97au577a r
17/19 tda7476 figure 7. tda7375 in s.e. mode with 4 output capacitors figure 8. tda7375 in s.e. mode with 2 output capacitors tda7375 +- -+ +- -+ ch1+ ch2+ ch3+ ch4+ ch5+ r ch5- ch4- ch3- ch2- ch1- tda7476 c out1 c out2 c out3 c out4 d97au575a tda7375 +- -+ +- -+ ch1+ ch2+ ch3+ ch4+ ch5+ ch5- ch4- ch3- ch2- ch1- tda7476 c out1 c out2 d97au576a r
tda7476 18/19 so24 dim. mm inch min. typ. max. min. typ. max. a 2.35 2.65 0.093 0.104 a1 0.10 0.30 0.004 0.012 a2 2.55 0.100 b 0.33 0.51 0.013 0.0200 c 0.23 0.32 0.009 0.013 d 15.20 15.60 0.598 0.614 e 7.40 7.60 0.291 0.299 e 1.27 0,050 h 10.0 10.65 0.394 0.419 h 0.25 0.75 0.010 0.030 k0 (min.), 8 (max.) l 0.40 1.27 0.016 0.050 be a2 a 1 13 24 d l h a1 c e k h x 45? so24 seating plane 0.10mm .004 a1 outline and mechanical data 12
information furnished is believed to be accurate and reliable. however, stmicroelectronics assumes no responsibility for the co nsequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. no license is granted by implication or otherwise under any patent or patent rights of stmicroelectronics. specifications mentioned in this publicati on are subject to change without notice. this publication supersedes and replaces all information previously supplied. stmicroelectronics prod ucts are not authorized for use as critical components in life support devices or systems without express written approval of stmicroelectro nics. the st logo is a registered trademark of stmicroelectronics ? 2001 stmicroelectronics - all rights reserved stmicroelectronics group of companies australia - brazil - china - finland - france - germany - hong kong - india - italy - japan - malaysia - malta - morocco - sin gapore - spain - sweden - switzerland - united kingdom - u.s.a. http://www.st.com 19/19 tda7476

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