TDA7375A datasheet(10/14 Pages) STMICROELECTRONICS

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rect operation for the device itself and for the

loudspeaker.

This particular kind of protection acts in such a

way to avoid the device is turned on (by ST-BY)

when a resistive path (less than 16 ohms) is pre-

sent between the output and GND. As the in-

volved circuitry is normally disabled when a cur-

rent higher than 5mA is flowing into the ST-BY

pin, it is important, in order not to disable it, to

have the external current source driving the ST-

BY pin limited to 5mA.

This extrafunction becomes particularly attractive

when, in the single ended configuration, one ca-

pacitor is shared between two outputs (see fig.

21).

Supposing that the output capacitor Cout for any

reason is shorted, the loudspeaker will not be

damaged being this soft short circuit condition re-

vealed.

Diagnostic Facilities

The TDA7375 is equipped with a diagnostic cir-

cuitry able to detect the following events:

Clipping in the output signal

Thermal shutdown

Output fault:

– short to GND

– short to VS

– soft short at turn on

The information is available across an open

collector output (pin 10) through a current sink-

ing when the event is detected

A current sinking at pin 10 is provided when a cer-

tain distortion level is reached at each output. This

function allows gain compression facility when-

ever the amplifier is overdriven.

Thermal Shutdown

In this case the output 10 will signal the proximity

of the junction temperature to the shutdown

threshold. Typically current sinking at pin 10 will

start ~10

°C before the shutdown threshold is

reached.

HANDLING OF THE DIAGNOSTIC INFORMA-

Figure 21.

Figure 22: Clipping Detection Waveforms

Figure 23: Output Fault Waveforms (see fig. 24)

TDA7375A

10/14

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