TDA7561

Diagnostics functional description

Doc ID 8326 Rev 6

13/27

Figure 18.

SVR and output pin behaviour (case 2: with turn-on diagnostic)

The information related to the outputs status is read and memorized at the end of the

current pulse top. The acquisition time is 100 ms (typ.). No audible noise is generated in the

process. As for short to GND / Vs the fault-detection thresholds remain unchanged from 26

dB to 12 dB gain setting. They are as follows:

Figure 19.

Short circuit detection thresholds

Concerning short across the speaker / open speaker, the threshold varies from 26 dB to 12

dB gain setting, since different loads are expected (either normal speaker's impedance or

high impedance). The values in case of 26 dB gain are as follows:

Figure 20.

Load detection thresholds - high gain setting

If the line-driver mode (Gv = 12 dB and line driver mode diagnostic = 1) is selected, the

same thresholds will change as follows:

Figure 21.

Load detection threshold - low gain setting