TDA7563A Datasheet, PDF (18/35 Pages) STMicroelectronics – 4 x 50W multifunction quad power amplifier with built-in diagnostics feature

Output DC offset detection
TDA7563A
Figure 27. Current detection: Load impedance |Z| vs. output peak voltage
Load |z| (Ohm)
50
Low current detection area
30
(Open load)
20
D5 = 1 of the DBx byres
Iout (peak) <250mA
Iout (peak) >500mA
10
High current detection area
5
(Normal load)
D5 = 0 of the DBx bytes
3
2
1
1
2
3
4
5
6
7
8
Vout (Peak)
4.2
Multiple faults
When more misconnections are simultaneously in place at the audio outputs, it is
guaranteed that at least one of them is initially read out. The others are notified after
successive cycles of I²C reading and faults removal, provided that the diagnostic is enabled.
This is true for both kinds of diagnostic (Turn on and Permanent).
The table below shows all the couples of double-fault possible. It should be taken into
account that a short circuit with the 4 ohm speaker unconnected is considered as double
fault.
Table 4.
Double fault table for turn on diagnostic
S. GND (so) S. GND (sk)
S. Vs
S. Across L. Open L.
S. GND (so)
S. GND
S. GND
S. Vs + S. GND
S. GND
S. GND
S. GND (sk)
/
S. GND
S. Vs
S. GND
Open L. (*)
S. Vs
/
/
S. Vs
S. Vs
S. Vs
S. Across L.
/
/
/
S. Across L.
N.A.
Open L.
/
/
/
/
Open L. (*)
S. GND (so) / S. GND (sk) in the above table make a distinction according to which of the 2
outputs is shorted to ground (test-current source side= so, test-current sink side = sk). More
precisely, in Channels LF and RR, so = CH+, sk = CH-; in Channels LR and RF, so = CH-, sk
= CH+.
In Permanent Diagnostic the table is the same, with only a difference concerning Open
Load(*), which is not among the recognizable faults. Should an Open Load be present
during the device's normal working, it would be detected at a subsequent Turn on Diagnostic
cycle (i.e. at the successive Car Radio Turn on).
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