TDA7476 Datasheet, PDF (9/15 Pages) STMicroelectronics – CAR RADIO DIAGNOSTIC PROCESSOR

TDA7476
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)
ADD1
S
010001A
0
ACK
P
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 memorized.
After a period Twait1 that depends on the value of the timing capacitor (see Timing) the µP redirects the
TDA7476 by the byte ADD2.
ADD2
S
010001A
1 ACK BYTE 1 ACK BYTE 2 ACK BYTE 3 ACK STOP
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 µP.
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
The TDA7476 provides two types of diagnostic information:
A) TURN-ON DIAGNOSTIC - The first time that the TDA7476 is addressed by I²CBus, the more com-
plete 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
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