+

Current Limit

OVSD

(§32V)

Thermal

Shutdown

INPUT

OUTPUT

GND

LM2937

PNP

Bandgap

Reference

LM2937-2.5, LM2937-3.3

www.ti.com

SNVS015F – FEBRUARY 1998 – REVISED NOVEMBER 2014

7 Detailed Description

7.1 Overview

The LM2937 is a positive voltage regulator capable of supplying up to 500 mA of load current. The use of a PNP

power transistor provides a low dropout voltage characteristic. With a load current of 500 mA the minimum input

to output voltage differential required for the output to remain in regulation is typically 0.5 V (1 V ensured

maximum over the full operating temperature range). Special circuitry has been incorporated to minimize the

quiescent current to typically only 10 mA with a full 500-mA load current when the input to output voltage

differential is greater than 3 V.

7.2 Functional Block Diagram

7.3 Feature Description

7.3.1 Thermal Shutdown (TSD)

The Thermal Shutdown circuitry of the LM2937 has been designed to protect the device against temporary

thermal overload conditions. The TSD circuitry is not intended to replace proper heat-sinking. Continuously

running the LM2937 device at thermal shutdown may degrade device reliability as the junction temperature will

be exceeding the absolute maximum junction temperature rating.

7.3.2 Short Circuit Current Limit

The output current limiting circuitry of the LM2937 has been designed to limit the output current in cases where

the load impedance is unusually low. This includes situations where the output may be shorted directly to ground.

Continuous operation of the LM2937 at the current limit will typically result in the LM2937 transitioning into

Thermal Shutdown mode.

7.3.3 Overvoltage Shutdown (OVSD)

Input voltages greater than typically 32 V will cause the LM2937 output to be disabled. When operating with the

input voltage greater than the maximum recommended input voltage of 26 V the device performance is not

ensured. Continuous operation with the input voltage greater than the maximum recommended input voltage is

discouraged.

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Product Folder Links: LM2937-2.5 LM2937-3.3