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Overcurrent Protection

Overtemperature Protection (OTP)

PTH12050W/L

SLTS214H – MAY 2003 – REVISED OCTOBER 2007

For protection against load faults, all modules incorporate output overcurrent protection. Applying a load that

exceeds the regulator's overcurrent threshold causes the regulated output to shut down. Following shutdown, a

module periodically attempts to recover by initiating a soft-start power-up. This is described as a hiccup mode of

operation, whereby, the module continues in a cycle of successive shutdown and power up until the load fault is

removed. During this period, the average current flowing into the fault is significantly reduced. Once the fault is

removed, the module automatically recovers and returns to normal operation.

The PTH12020, PTV12020, and PTH12030 products have overtemperature protection. These products have an

on-board temperature sensor that protects the module's internal circuitry against excessively high temperatures.

A rise in the internal temperature may be the result of a drop in airflow, or a high ambient temperature. If the

internal temperature exceeds the OTP threshold, the module's Inhibit control is internally pulled low. This turns

the output off. The output voltage drops as the external output capacitors are discharged by the load circuit. The

recovery is automatic, and begins with a soft-start power up. It occurs when the sensed temperature decreases

by about 10

°C below the trip point.

Note: The overtemperature protection is a last resort mechanism to prevent thermal stress to the regulator.

Operation at or close to the thermal shutdown temperature is not recommended and will reduce the

long-term reliability of the module. Always operate the regulator within the specified Safe Operating Area

(SOA) limits for the worst-case conditions of ambient temperature and airflow.

Copyright © 2003–2007, Texas Instruments Incorporated

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