TDA7476

14/19

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

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;

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.

START

ADD2

ACK

BYTE1

ACK

BYTE2

ACK

BYTE3

STOP

START

ADD2

ACK

BYTE1

ACK

BYTE2

ACK

BYTE3

ACK

STOP