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TLVM365R1: Output voltage low

Connor Kirkpatrick
Prodigy 20 points
Part Number: TLVM365R1

Tool/software:

I had a board made that measures voltage and current controlled by an in house sensor monitor. When powering the board with ~16V the TLVM365R1 input is correct at ~16V but outputs only 0.91V instead of 5V. The Vcc pin is held at around 3.3V. I have attached the schematic and art files.

RD3-0037_Art.pdfRD3-0037_Schematic.pdf

  • 0
    TI__Mastermind 28080 points

    Hi Connor,

    Sorry to hear you are having trouble. Were you able to disconnect the TLVM365R1 module by itself away from the other devices, and does it regulate? And does this 0.91V output track across different devices i.e from a known good unit?

    Thanks,

    Richard

  • 0 in reply to Richard Fu22
    Prodigy 20 points

    Hi Richard,

    Thanks for your reply, I cut the trace on the board seen below and the output increased to 4.9V. Do you have any idea what would be causing the reduced voltage from this trace? I have included a photo of the schematic where the trace cut off leads to.

  • 0 in reply to Connor Kirkpatrick
    Prodigy 20 points

    Update: severed the trace further, there seems to be an issue with SN74LVC1G74DCUR. When applying a 5V 0.3Amax supply to the Vcc pin, the supply goes to 0.5V 0.25A. Is there an issue with the schematic or layout for this component?

  • 0 in reply to Connor Kirkpatrick
    TI__Mastermind 36490 points

    Hello Conner,

    If I understand correctly, you are saying when you connect the VCC pin of the SN74 device to the output of the TLVM, the output drops.  this suggests there is a fault with the SN74 device.  A way to check the TLVM is to disconnect all loads, and connect and electronic load and load to the expected level and check the TLVM can regulate at the expected currents.  

    alsoturnatively check the impedebce of the VCC with of the SN74 and compare to a known good unit, if damaged, replace.

    David.