TDA7567PD

Diagnostics functional description

Doc ID 16903 Rev 2

13/30

Figure 7.

SVR and output pin behavior (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 16 dB gain setting. They are as follows:

Figure 8.

Short circuit detection thresholds

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

16 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 9.

Load detection thresholds - high gain setting 26 dB

If the line driver mode (Gv = 16 dB and line driver mode diagnostic = 1) is selected, the

same thresholds will change as follows:

Figure 10. Load detection thresholds - low gain setting 16 dB

Bias (power amp turn-on)

permitted time

Turn-on diagnostic

acquisition time (100mS Typ)

t

Read Data

Permanent diagnostic

acquisition time (100mS Typ)

Permanent Diagnostics data (output)

permitted time

Diagnostic Enable

(Turn-on)

Turn-on Diagnostics data (output)

permitted time

I2CB DATA

Vsvr

Out

Diagnostic Enable

(Permanent)

FAULT

event

D01AU1253

S.C. to GND

x

S.C. to Vs

0V

1.8V

VS-1.8V

VS

x

Normal Operation

1.2V

VS-1.2V

S.C. across Load

x

Open Load

0V

1.5

Ω

45

Ω

Infinite

x

Normal Operation

0.5

Ω

85

Ω

AC00060

S.C. across Load

x

Open Load

0

Ω

7

Ω

180

Ω

infinite

x

Normal Operation

1.5

Ω

330

Ω