TDA7562 Datasheet, PDF (9/17 Pages) STMicroelectronics – MULTIFUNCTION QUAD POWER AMPLIFIER WITH BUILT-IN DIAGNOSTICS FEATURES

TDA7562
As for SHORT TO GND / Vs the fault-detection thresholds remain unchanged from 30 dB to 16 dB gain setting.
They are as follows:
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
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Concerning SHORT ACROSS THE SPEAKER , the threshold varies from 30 dB to 16 dB gain setting, since
different loads are expected (either normal speaker's impedance or high impedance). The values in case of 30
dB gain are as follows:
S.C. across Load x
Normal Operation
0V
0.5Ω 1.5Ω
Infinite
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If the Line-Driver mode (Gv= 16 dB and Line Driver Mode diagnostic = 1) is selected, the same thresholds will
change as follows:
S.C. across Load x
Normal Operation
0Ω
1.5Ω 4.5Ω
infinite
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OUTPUT DC OFFSET DETECTION
Any DC output offset exceeding ± 2V are signalled out. This inconvenient might occur as a consequence of ini-
tially defective or aged and worn-out input capacitors feeding a DC component to the inputs, so putting the
speakers at risk of overheating.
This diagnostic has to be performed with low-level output AC signal (or Vin = 0).
The test is run with selectable time duration by microprocessor (from a "start" to a "stop" command):
– START = Last reading operation or setting IB1 - D5 - (OFFSET enable) to 1
– STOP = Actual reading operation
Excess offset is signalled out if persistent throughout the assigned testing time. This feature is disabled if any
overloads leading to activation of the short-circuit protection occurs in the process.
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.
The table below shows all the couples of double-fault possible. It should be taken into account that a short circuit
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