Practical information

STA541SA

20/26

Doc ID 16988 Rev 2

7.5

Handling the diagnostic information

As different diagnostic information (clipping detection, output fault, approaching thermal

shutdown) becomes available at pin 10 so the behavior of the signal at this pin changes.

In order to discriminate the event the signal on pin 10 must be interpreted correctly.

Figure 20 shows a combination of events on the output waveform and the corresponding

output on pin 10.

These events could be diagnosed based on the timing of the output signal on pin 10. For

example, the clip-detector signalling under fault conditions could produce a low level for a

short time. On the other hand, an output short circuit would probably produce a low level for

a much longer time. With these assumptions, an interface circuit based on the one shown in

Figure 21 could differentiate the information and flag the appropriate circuits.

Figure 20.

Waveforms

Figure 21.

Interface circuit diagram

t

t

t

STBY PIN

VOLTAGE

Vs

OUTPUT

WAVEFORM

Vpin 10

WAVEFORM

SHORT TO GND

OR TO Vs

D05AU1604mod

CLIPPING

THERMAL

PROXIMITY

VREF

VREF1

VREF2

R1

R2

Clip detector

(to gain compressor / tone control)

Fault, thermal shutdown

(to power supply section, voltage regulator,

flashing system)

STA541SA

R1 << R2

VREF > VREF1 >> VREF2

10