TDA7575PD Datasheet, PDF (14/17 Pages) STMicroelectronics – MULTIFUNCTION DUAL BRIDGE POWER AMPLIFIER WITH INTEGRATED DIGITAL DIAGNOSTICS

TDA7575PD
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 microproces-
sor level (over than half a second is recommended).
Fig. G: Restart timing without Diagnostic Enable (Permanent)
Each 1mS time, a sampling of the fault is done
Out
1-2mS
1mS
1mS 1mS
1mS
Overcurrent and short
circuit protection intervention
(i.e. short circuit to GND)
t
Short circuit removed
Fig H: Restart timing with Diagnostic Enable (Permanent)
1mS
100mS
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
– 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.
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