TDA7575BPD View Datasheet(PDF) - STMicroelectronics

Part Name

Description

Manufacturer

TDA7575BPD

2 x 75W multifunction dual-bridge power amplifier with integrated digital diagnostics

STMicroelectronics 

TDA7575B

Diagnostics functional description

7

Diagnostics functional description

7.1

Turn-on diagnostic

It is activated at the turn-on (stand-by out) under I2C bus request. Detectable output faults are:

– SHORT TO GND

– SHORT TO Vs

– SHORT ACROSS THE SPEAKER

– OPEN SPEAKER

To verify if any of the above misconnections are in place, a subsonic (inaudible) current

pulse (Figure 29) is internally generated, sent through the speaker(s) and sunk back. The

Turn On diagnostic status is internally stored until a successive diagnostic pulse is

requested (after a I2C reading).

If the "stand-by out" and "diag. enable" commands are both given through a single

programming step, the pulse takes place first (power stage still in stand-by mode, low,

outputs = high impedance).

Afterwards, when the Amplifier is biased, the PERMANENT diagnostic takes place. The

previous Turn On state is kept until a short appears at the outputs.

Figure 29. Turn - on diagnostic: working principle

Vs~5V

Isource

CH+

CH-

I (mA)

Isource

Isink

Isink

~100mS

Measure time

t (ms)

Fig. Figure 30 and Figure 31 show SVR and OUTPUT waveforms at the turn-on (stand-by

out) with and without Turn-on diagnostic.

Figure 30. SVR and output behavior - case 1: without turn-on diagnostic

Vsvr

Out

Permanent diagnostic

acquisition time (100mS Typ)

Bias (power amp turn-on)

Diagnostic Enable

(Permanent)

FAULT

event

t

Read Data

I2CB DATA

Permanent Diagnostics data (output)

permitted time

23/32

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