TDA7563B Datasheet, PDF (14/33 Pages) STMicroelectronics – 4 x 50W multifunction quad power amplifier with built-in diagnostics feature

Diagnostics functional description
4
Diagnostics functional description
TDA7563B
4.1
Turn-on diagnostic
It is activated at the turn-on (stand-by out) under I²Cbus 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 (fig. 19) 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 19. Turn - on diagnostic: working principle
Vs~5V
I (mA)
Isource
Isource
CH+
CH-
Isink
Isink
~100mS
Measure time
t (ms)
Figure 20 and 21 show SVR and OUTPUT waveforms at the turn-on (stand-by out) with and
without turn-on diagnostic.
Figure 20. SVR and output behaviour (Case 1: without turn-on diagnostic)
Vsvr
Out
Permanent diagnostic
acquisition time (100mS Typ)
14/33
Bias (power amp turn-on)
Diagnostic Enable
(Permanent)
FAULT
event
t
Read Data
I2CB DATA
Permanent Diagnostics data (output)
permitted time