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TPSM863252: TPSM863252

Dattatraya Bathe
Prodigy 10 points
Part Number: TPSM863252

Hi,

I am using TPSM863252 to Generate 2.5V from 3.3V. The load current maximum is 0.5A. Circuit is as below,

When 3.3V is turned ON, the output of the IC goes to 2.08V and gets stuck there. In that state if a multimeter is connected to measure the VFB voltage then the output jumps to 2.5V and everything works fine. If the multimeter is kept connected to the VFB pin before powering on the 3.3V, 2.5V works properly.  I added feed forward capacitor of 22pF, but still it doesn't work.

Can you please help to resolve this issue?

  • 0
    TI__Expert 8530 points

    Hi,

    As it's in weekend, my colleague will reply to you on Monday. Thanks for your patience.

  • 0
    TI__Mastermind 19350 points

    Hi ,

    Thanks for reaching out!

    For the output voltage, did you measure TP69 or ADVVH_SW? And when you tested the fb voltage with multimeter, what is the value of FB node?

    What if you disconnected the downstream load? If there is no load or if you use E-load instead, what will be the output voltage?

    And even though 22pF will not work for your case, I would still suggest that you can add Cff for loop stability.

    BRs

    Lucia

  • 0 in reply to Lucia Gao
    Prodigy 10 points

    For the output voltage, did you measure TP69 or ADVVH_SW? And when you tested the fb voltage with multimeter, what is the value of FB node? – Yes, I measured the voltage at TP69. When the voltage is 2.078V the feedback voltage is around 0.525V which increases immediately as soon as I touch the feedback node.

    What if you disconnected the downstream load? If there is no load or if you use E-load instead, what will be the output voltage? – When I disconnected downstream load the voltage rises immediately to 2.5V.

    And even though 22pF will not work for your case, I would still suggest that you can add Cff for loop stability. - Ok

  • 0 in reply to Dattatraya Bathe
    TI__Mastermind 19350 points

    Hi ,

    Thanks for your feedback!

    1. I would suggest you can check any solder issue with fb resistors (R619, R618).

    2. Would you have chance to check with E-load not the actual load? If with E-load and set as 0.5A, will Vout also drop?

    3. When the Vout drops to 2.08V, could you pls share me the waveform of SW and Vout and compare with no load condition?

    Thanks!

    BRs

    Lucia