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TDA7476

The following table shows the result pointed out by TDA7476 when multiple misconnections are present:

(*) CH means CH+ or CH-

AUX1 - AUX2

s

Voltage across the sensing resistors

s

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

s

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

s

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

more than 2 sec (typ).

s

Output voltage

AUX1 - AUX2

s

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

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

or "open load".

ACTUAL FAULTS

POINTED OUT FAULT

S.C. CH+ to GND + OPEN LOAD

S.C. to GND

S.C. CH(*) to GND + S.C. ACROSS LOAD

S.C. to GND

S.C. CH- to GND + OPEN LOAD

OPEN LOAD

S.C. to GND

x

Open Load

0.5V

125mV

0V

x

Normal Operation

0.85V

85mV

D97AU572A

S.C. to GND

x

S.C. to Vs

0V

1.2V

x

Normal Operation

0.8V

D97AU573B

S.C. to GND

x

Open Load

0.5V

125mV

0V

x

Normal Operation

0.85V

85mV

D97AU574A