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LM3940: LDO

Abhishek Singh2
Prodigy 220 points
Part Number: LM3940

Hello, 

I'm using LM3940 in my project to generate 3.3 V supply for a microcontroller. The input is 5.2 V. For the initial period after assembly this IC was giving me 3.28 V, but now it is showing 3.7 V output which is out of the recommended region of operation for the microcontroller. The circuit for LM3940 is same as the "simplified circuit" mentioned in the its datasheet. I wanted to know the possible reasons because of which this issue can happen.

Regards, 

Abhishek Kumar Singh 

  • 0
    TI__Mastermind 23361 points

    Hi Abhishek, 

    We would need to have more details to help you. Please provide your schematic (I know it's similar to the one in the datasheet, but we still need it to confirm), and your test results, including waveforms that clearly show Vin, Vout startup. 

    Regards, 
    Jason Song