LM2936 datasheet(7/10 Pages) NSC

7 / 10 page

Applications Information (Continued)

On the SO-8 package the four ground pins are thermally

connected to the backside of the die. Adding approximately

0.04 square inches of 2 oz. copper pad area to these four

pins will improve the

JA rating to approximately 110˚C/W. If

this extra pad are is placed directly beneath the package

there should not be any impact on board density.

On the TO-252 package the ground tab is thermally con-

nected to the backside of the die. Adding 1 square inch of 2

oz. copper pad area directly under the ground tab will im-

prove the

JA rating to approximately 50˚C/W.

While the LM2936 has an internally set thermal shutdown

point of typically 150˚C, this is intended as a safety feature

only. Continuous operation near the thermal shutdown tem-

perature should be avoided as it may have a negative affect

on the life of the device.

While the LM2936-3.0 will survive input transients to +60V,

output regulation is not guaranteed for input voltages greater

than 40V. The LM2936 will not withstand a output short

circuit with the input above 40V because of safe operating

area limitations in the internal PNP pass device. With input

voltages above 60V the LM2936 will break down with cata-

strophic effects on the regulator and possibly the load as

well. Do not use this device in a design where the input

operating voltage may exceed 40V, or where transients are

likely to exceed 60V.

Shutdown Pin

The LM2936BM has a pin for shutting down the regulator

output. Applying a Logic Level High (>2.0V) to the Shutdown

pin will cause the output to turn off. Leaving the Shutdown

pin open, connecting it to Ground, or applying a Logic Level

Low (<0.6V) will allow the regulator output to turn on.

LM2936 Scheda tecnica(PDF) 7 Page - National Semiconductor (TI)