LM78L: Bipolar supply, diode protection?

James VDC

Part Number: LM78L
I am working on a design that utilizes LM78L15 and LM79L15 to regulate +/-15VDC rails. I do not find any reference in either datasheet to the use of protection diodes for Reverse Polarity (Shunt diode to ground from output) and Reverse Bias (series diode from output to input). Are these devices still needed with the LM78L parts?

over 3 years ago

0 Jason Song over 3 years ago

TI__Mastermind 23361 points

Hi James,

Unless stated otherwise, the LDO will need special consideration on the reverse polarity and reverse current protection. We only have a very limited number of the LDO that mostly targets for automotive have the built-in reverse polarity and reverse current protection like TPS7B7701/02. So the answer for your questions would yes.

Regards,
Jason Song

0 James VDC over 3 years ago in reply to Jason Song

Prodigy 240 points

Hi Jason and thank you for your response. I have since added the protection diodes to my design. As a follow-up question; am I correct in assuming that the use of schottky barrier diodes would be preferred in both of these instances over standard silicon rectifier diodes?

0 Jason Song over 3 years ago in reply to James VDC

TI__Mastermind 23361 points

Yes, schottky is recommended.

0 James VDC over 3 years ago in reply to Jason Song

Prodigy 240 points

Thank you Jason.

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LM78L: Bipolar supply, diode protection?