TDA7476_01 Datasheet, PDF (14/19 Pages) STMicroelectronics – CAR RADIO DIAGNOSTIC PROCESSOR

TDA7476
START
ADD2
ACK
BYTE1
ACK
BYTE2
ACK
BYTE3
STOP
s 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 µP sends ADD2, receives BYTE1, BYTE2, BYTE3, and sends
the acknowlegde after BYTE3
START ADD2
ACK
BYTE1
ACK
BYTE2
ACK
BYTE3
ACK
STOP
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 = 10µF 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
s 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
s The purpose of this pin is to alert the µP and start with the permanent diagnostic routine only if faults
are present, thus avoiding CPU's waste of time.
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