TDA7491LP

Applications information

Doc ID 13541 Rev 5

31/37

5.7

Protection functions

The TDA7491LP is fully protected against undervoltages, overcurrents and thermal

overloads as explained here.

Undervoltage protection (UVP)

on page 10 the undervoltage protection is activated which forces the outputs to the

high-impedance state. When the supply voltage recovers the device restarts.

Overcurrent protection (OCP)

page 10 the overcurrent protection is activated which forces the outputs to the

high-impedance state. Periodically, the device attempts to restart. If the overcurrent

by the R-C components connected to pin STBY.

Thermal protection (OTP)

the positive and negative PWM outputs are forced to 50% duty cycle. If the junction

temperature reaches the value for Tj given in Table 5: Electrical specifications on page 10

the device shuts down and the output is forced to the high impedance state. When the

device cools sufficiently the device restarts.

5.8

Diagnostic output

The output pin DIAG is an open drain transistor. When the protection is activated it is in the

high-impedance state. The pin can be connected to a power supply (<18 V) by a pull-up

resistor whose value is limited by the maximum sinking current (200 µA) of the pin.

Figure 35.

Behavior of pin DIAG for various protection conditions

TDA7491LP

Protection logic

R1

DIAG

VDD

VDD

Overcurrent

protection

Restart

Restart

UV, OT

protection