Need Help with LM317 Part Substitute

I had designed a circuit with LM317AT originally and purchased one SOT style which was LM317DCYR. Circuit did not operate as it should have. I feel that there was a difference that I did not notice. Would LM317AEMP/NOPB be the correct substitute?

Welcome to the Digi-Key TechForum Jmorales1.
I do not see anything, that jumps out at me, that would be a reason the LM317DCYR would not of worked.
LM317AEMP/NOPB should work also, but we do not have stock.
I searched for another option that we have in stock, and I found 296-21390-1-ND, which is the Manufacturer’s part number of LM317KTTR.
Please check the datasheet to verify compatibility to your application.

I did just notice that LM317AT stated the Adjust pin was neither I/O but for LM317DCYR the Adjust pin was an Input. Would that have any effect?

Hi Jmorales1,

This should not make any difference. Thanks!

The thermal properties of the different device packages differ substantially; this may be sufficient to cause differences in observed behavior.

A bit more detail with respect to the symptoms of the problem would be helpful for identifying likely causes.