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TLV1117 ADJ not adjusting.

Other Parts Discussed in Thread: TLV1117

Hello all. 

I recently copied one of my older designs with a TLV1117 ADJ with a pot. The old (working design) used one of the surface mount packages but for the new one I swapped to the TO-220 pack. I just got my pcbs built up and adjusting the pot has no affect on the output. The only thing I added was a protection diode from pins 2-3 but I tried removing it and still having issues. I checked that the pot is actually adjusting across its full range. I thought maybe my load was too light so I added a resistor to pull some current, that made no difference. The voltages out are about 1V below the input, like the device is just spitting out with the minimum dropout voltage. I attached the main power section of my circuit. 
Any ideas would be great, I need this working asap. 

  • Douglas,

    The schematic looks correct and your trouble shooting ideas are good.
    While unlikely check for oscillation at outputs.
    Could the device be wired backward? (Input and output swapped?
    Try connect adj pin to ground via 100 ohm resistor to see if adjust pin goes close to 0V and output goes to 1.25V.