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TDA7492

Applications information

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6.6

Protection functions

The TDA7492 is fully protected against overvoltages, undervoltages, overcurrents and

thermal overloads as explained here.

Overvoltage protection (OVP)

If the supply voltage exceeds the value for VOVP given in Table 5: Electrical specifications

on page 9 the overvoltage protection is activated which forces the outputs to the

high-impedance state. When the supply voltage drops to below the threshold value the

device restarts.

Undervoltage protection (UVP)

If the supply voltage drops below the value for VUVP given in Table 5: Electrical

specifications on page 9 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)

If the output current exceeds the value for IOCP given in Table 5: Electrical specifications on

page 9 the overcurrent protection is activated which forces the outputs to the

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

condition is still present then the OCP remains active. The restart time, TOC, is determined

by the R-C components connected to pin STBY.

Thermal protection (OTP)

If the junction temperature, Tj, reaches 145 °C (nominally), the device goes to mute mode

and 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 9 the

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

cools sufficiently the device restarts.

6.7

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 (<26 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

TDA7492

Protection logic

R1

DIAG

VDD

VDD

Overcurrent

protection

Restart

Restart

OV, UV, OT

protection