TURN-ON DIAGNOSTIC - THRESHOLDS

CH1, CH2, CH3, CH4, CH5

Output voltage during test. (The power amplifier must be in ST-BY mode).

Note: some faults can mask others if they are present at the same moment on the same channel:

- If there is a short to GND and an open load on the same channel, the TDA7476 gives information

only about one of them, depending on the wire on which the short circuit is present.

- The short circuit to GND masks any short circuit across the load.

- The short circuit to Vs masks any short or open load.

The minimum voltage of the AUX IN pin to sense the open load condition is 2V.

The minimum voltage of the AUX IN pin to detect the short circuit to GND, by sensing the drop on the

resistors is 4.5V. If this voltage falls below 2V, the AUX in is considered short circuited to GND. From

2V to 4.5V the sensing circuit can detect a short circuit in both ways (by sensing across the resistor or

through the voltage between the AUX IN pin and GND).

PERMANENT DIAGNOSTIC - THRESHOLDS

CH1, CH2, CH3, CH4, CH5

The circuit will recognize as a fault condition any situation where the following short circuit voltages

last more than 2 sec (typ).

Output voltage

AUX1 - AUX2

The voltage across the resistors Rsens1 or Rsens2 is sensed. The circuit will recognize as a fault con-

dition any situation where the following voltages last more than 2sec (typ) in the region ”S.C.to GND”

or ”open load”.

The minimum voltage of the AUX IN pins to sense the open load condition is 2V.

The minimum voltage of the AUX IN pin to detect the short circuit to GND by sensing drop on the re-

sistor is 4.5V. If this voltage is below 2V, the AUX line is considered short circuited to GND. From 2V

to 4.5V the sensing circuit can detect a short circuit in both ways (by sensing across the resistor or

through the voltage between the AUX IN pin and GND).

S.C. across Load

x

Open Load

0V

22mV

220mV

x

Normal Operation

5mV

550mV

D97AU631A

AUX1 - AUX2

Voltage across the sensing resistors.

S.C. to GND

x

Open Load

0.5V

125mV

0V

x

Normal Operation

0.75V

85mV

D97AU572

S.C. to GND

x

S.C. to Vs

0V

1.2V

x

Normal Operation

0.8V

D97AU573A

S.C. to GND

x

Open Load

0.5V

125mV

0V

x

Normal Operation

0.75V

85mV

D97AU574

Voltage across the load during test. (The power amplifier must be in ST-BY mode).

D96AU502A

S.C. to GND

x

S.C. to Vs

0V

1.2V

x

Normal Operation

0.8V

TDA7476

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