TDA7491LP13TR Datasheet, PDF (31/37 Pages) STMicroelectronics – 2 x 5-watt dual BTL class-D audio amplifier

TDA7491LP
Applications information
5.7
Protection functions
The TDA7491LP is fully protected against undervoltages, overcurrents and thermal
overloads as explained here.
Undervoltage protection (UVP)
If the supply voltage drops below the value of V_UVP given in Table 5: Electrical specifications
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)
If the output current exceeds the value of I_OCP given in Table 5: Electrical specifications on
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
condition is still present then the OCP remains active. The restart time, T_OC, is determined
by the R-C components connected to pin STBY.
Thermal protection (OTP)
If the junction temperature, T_j, reaches 145 °C (nominal), 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 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
VDD
TDA7491LP
R1
Protection logic
DIAG
VDD
Overcurrent
protection
Restart
Restart
UV, OT
protection
Doc ID 13541 Rev 5
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