TPS54310-EP
www.ti.com ..................................................................................................................................................................................................... SLVS818–APRIL 2008
Thermal Shutdown
Power Good (PWRGD)
The device uses the thermal shutdown to turn off the
power MOSFETs and disable the controller if the
junction temperature exceeds 150°C. The device is
released from shutdown when the junction
temperature decreases to 10°C below the thermal
shutdown trip point and starts up under control of the
slow-start circuit. Thermal shutdown provides
protection when an overload condition is sustained for
several milliseconds. With a persistent fault condition,
the device cycles continuously; starting up by control
of the soft-start circuit, heating up due to the fault,
and then shutting down upon reaching the thermal
shutdown point.
The power good circuit monitors for under voltage
conditions on VSENSE. If the voltage on VSENSE is
10% below the reference voltage, the open-drain
PWRGD output is pulled low. PWRGD is also pulled
low if VIN is less than the UVLO threshold, or
SS/ENA is low, or thermal shutdown is asserted.
When VIN = UVLO threshold, SS/ENA = enable
threshold, and VSENSE > 90% of Vref, the open drain
output of the PWRGD pin is high. A hysteresis
voltage equal to 3% of Vref and a 35-µs falling edge
deglitch circuit prevent tripping of the power good
comparator due to high frequency noise.
Copyright © 2008, Texas Instruments Incorporated
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