TDA7564B Datasheet, PDF (15/34 Pages) STMicroelectronics – 4 x 50W multifunction quad power amplifier with built-in diagnostics features

TDA7564B
Diagnostics functional description
Figure 21. SVR and output pin behavior (case 2: with turn-on diagnostic)
Vsvr
Out
Turn-on diagnostic
acquisition time (100mS Typ)
Permanent diagnostic
acquisition time (100mS Typ)
t
Diagnostic Enable
(Turn-on)
Turn-on Diagnostics data (output)
permitted time
Diagnostic Enable
(Permanent)
FAULT
event
Bias (power amp turn-on)
permitted time
Read Data
Permanent Diagnostics data (output)
permitted time
I2CB DATA
The information related to the outputs status is read and memorized at the end of the
current pulse top. The acquisition time is 100 ms (typ.). No audible noise is generated in the
process. As for SHORT TO GND / Vs the fault-detection thresholds remain unchanged from
26 dB to 12 dB gain setting. They are as follows:
Figure 22. Short circuit detection thresholds
S.C. to GND x Normal Operation x
S.C. to Vs
0V
1.2V 1.8V
V_S-1.8V V_S-1.2V
V_S
D01AU1253
Concerning Short across the speaker / Open speaker, the threshold varies from 26 dB to 12
dB gain setting, since different loads are expected (either normal speaker's impedance or
high impedance). The values in case of 26 dB gain are as follows:
Figure 23. Load detection thresholds - high gain setting
S.C. across Load x Normal Operation x
Open Load
0V
0.5Ω 1.5Ω
45Ω
85Ω
Infinite
AC00060
If the Line-Driver mode (Gv= 12 dB and Line Driver Mode diagnostic = 1) is selected, the
same thresholds will change as follows:
Figure 24. Load detection threshold - low gain setting
S.C. across Load x Normal Operation x
Open Load
0Ω
2Ω 7Ω
180Ω 330Ω
infinite
D02AU1340
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