TDA7564B

Multiple faults

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5

Multiple faults

When more misconnections are simultaneously in place at the audio outputs, it is

guaranteed that at least one of them is initially read out. The others are notified after

This is true for both kinds of diagnostic (Turn on and Permanent).

The table below shows all the couples of double-fault possible. It should be taken into

account that a short circuit with the 4 ohm speaker unconnected is considered as double

fault.

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 Channels LF and RR, so = CH+, sk = CH-; in Channels LR and RF, so = CH-, 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).

5.1

Faults availability

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

period, it will be sent out.

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.

Table 5.

Double fault table for turn-on diagnostic

S. GND (so)

S. GND (sk)

S. Vs

S. Across L.

Open L.

S. GND (so)

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. (*)