Diagnostics functional description

TDA7575B

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Table 10.

Double fault table for turn on diagnostic

S. GND (so) / S. GND (sk) in the above table make a distinction according to which of the 2

outputs is shorted to ground (test-current source side= so, test-current sink side = sk). More

precisely, in both the Channels SO = CH+, and SK = CH-.

In Permanent Diagnostic the table is the same, with only a difference concerning Open

Load(*), which is not among the recognizable faults. Should an Open Load be present

during the device's normal working, it would be detected at a subsequent Turn on Diagnostic

cycle (i.e. at the successive Car Radio Turn on).

7.6

Faults availability

measurements inside a defined period of time. If the fault is stable throughout the whole

period, it will be sent out. This is true for DC diagnostic (Turn on and Permanent), for Offset

Detector.

To guarantee always resident functions, every kind of diagnostic cycles (Turn on,

diag. cycle (i.e. The device is in Turn On state, with a short to Gnd, then the short is

are necessary.

7.7

A correct turn on/off sequence respectful of the diagnostic timings and producing no audible

noises could be as follows (after battery connection):

–

TURN-ON: (STAND-BY OUT + DIAG ENABLE) --- 500 ms (min) --- MUTING OUT

–

TURN-OFF: MUTING IN --- 20 ms --- (DIAG DISABLE + STAND-BY IN)

disappear).

–

OFFSET TEST: Device in Play (no signal) --

–

S. GND (sc)

S. GND (sk)

S. Vs

S. Across L.

Open L.

S. GND (sc)

S. GND

S. GND

S. Vs + S.

GND

S. GND

S. GND

S. GND (sk)

/

S. GND

S. Vs

S. GND

Open L. (*)

S. Vs

/

/

S. Vs

S. Vs

S. Vs

S. Across L.

/

/

/

S. Across L.

N.A.

Open L.

/

/

/

/

Open L. (*)