TDA7563 Datasheet, PDF (11/20 Pages) STMicroelectronics – MULTIFUNCTION QUAD POWER AMPLIFIER WITH BUILT-IN DIAGNOSTICS FEATURES

TDA7563
– To avoid momentary re-circulation spikes from giving erroneous diagnostics, a check of the output sta-
tus is made after 1ms: if normal situation (no overloads) is detected, the diagnostic is not performed and
the channel returns back active.
– Instead, if an overload is detected during the check after 1 ms, then a diagnostic cycle having a duration
of about 100 ms is started.
– After a diagnostic cycle, the audio channel interested by the fault is switched to RESTART mode. The
relevant data are stored inside the device and can be read by the microprocessor. When one cycle has
terminated, the next one is activated by an I²C reading. This is to ensure continuous diagnostics
throughout the car-radio operating time.
– To check the status of the device a sampling system is needed. The timing is chosen at microprocessor
level (over half a second is recommended).
Figure 19. Restart timing without Diagnostic Enable (Permanent) - Each 1mS time, a sampling of
the fault is done
1-2mS
1mS
1mS 1mS
1mS
Out
Overcurrent and short
circuit protection intervention
(i.e. short circuit to GND)
t
Short circuit removed
Figure 20. Restart timing with Diagnostic Enable (Permanent)
1-2mS
100/200mS
1mS
1mS
Overcurrent and short
circuit protection intervention
(i.e. short circuit to GND)
t
Short circuit removed
OUTPUT DC OFFSET DETECTION
Any DC output offset exceeding +/- 2 V are signalled out. This inconvenient might occur as a consequence of
initially 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
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