TDA7575B Datasheet, PDF (27/32 Pages) STMicroelectronics – 2 x 75W multifunction dual-bridge power amplifier with integrated digital diagnostics

TDA7575B
Diagnostics functional description
are recommended for their negligible acoustic impact and also to maximize the impedance
module's ratio between with tweeter-on and tweeter-off.
Figure 37 shows the Load Impedance as a function of the peak output voltage and the
relevant diagnostic fields.
This feature is disabled if any overloads leading to activation of the short-circuit protection
occurs in the process.
Figure 37. Current detection high: 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
IB2(D0) = 0
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)
Figure 38. Current detection low: 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) <125mA
Iout (peak) >250mA
10
IB2(D0) = 1
High current detection area
5
(Normal load)
D5 = 0 of the DBx bytes
3
2
1
0.5
1
1.5
2
2.5
3
Vout (Peak)
3.5
4
7.5
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 4Ω speaker unconnected is considered as double fault.
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