TDA7566_10 Datasheet, PDF (15/29 Pages) STMicroelectronics – 4 x 40 W multifunction quad power amplifier with built-in diagnostics features

TDA7566
Diagnostics functional description
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 22. Restart timing without diagnostic enable (Permanent)
each 1 ms 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 23. Restart timing with diagnostic enable (Permanent)
1mS
100mS
1mS
1mS
Overcurrent and short
(i.e. short circuit to GND)
t
Short circuit removed
4.3
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 V_in = 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.
Doc ID 9801Rev 5
15/29