LM317M: LM317MDCY Schematics Review

Ananthesh Acharya

Intellectual 535 points

Part Number: LM317M

Hi,

The following is the schematic used for 12v input to 2.5v output (Linear regulator used LM317MDCY).

I wanted to review the design and provide your valuable feedback.

Thanks in advance

with Regards,

Ananthesh

over 8 years ago

0 David Hopkins over 8 years ago

TI__Expert 8905 points

Hi Ananthesh,

The schematic looks ok, however what is the current level? You could have some thermal issues.

-David

0 Ananthesh Acharya over 8 years ago in reply to David Hopkins

Intellectual 535 points

Hi David,

Thank you for your reply.

The input is 12V, 1A & Output is 2.5V, 500mA.

Also i need to confirm the Diode D5 and D7 used for reverse current protection meets all the requirement.
Waiting for your reply.

with Regards,
Ananthesh

0 Ananthesh Acharya over 8 years ago in reply to Ananthesh Acharya

Intellectual 535 points

Hi David,

May i know the reason for thermal issue.
How it can be solved with respect to above schematics and how should i take care during the CAD design?

with Regards,
Ananthesh

0 Ananthesh Acharya over 8 years ago in reply to Ananthesh Acharya

Intellectual 535 points

Hi David,

Gentle remainder!!

with Regards,
Ananthesh

0 David Hopkins over 8 years ago in reply to Ananthesh Acharya

TI__Expert 8905 points

Hi Ananthesh,

Sorry for the delay - the thermal issue is because of the high power dissipation (12V - 2.5V ) * 0.5A *66.8C/W = 317C rise in junction temp.

A larger package, different cooling methods (like fans), or a dc-dc converter can be used to avoid the thermal issue.

-David

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LM317M: LM317MDCY Schematics Review