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TPS53681: Powering up the slave FET issue.

Kiran Kumar R
Intellectual 265 points
Part Number: TPS53681
Other Parts Discussed in Thread: CSD95410RRB,

Hi Ti Team,

We are using TPS53681RSBT with CSD95410RRB in our design. the design is as follows.

In one of our boards, CSD95410RRB is unable to provide output voltage. (This device was working fine earlier). We tried controlling multiphase controller through fusion digital tool and we observe that when we enable the slave 1 through GUI, we were getting Vout over voltage fault and was getting disabled upon fault. when we probed the voltage, the voltage was seen to rise till 1.8v (this is too high as the load is 0.85v). Attached is the output voltage waveform for your reference.


also, attaching the fault logs screenshot for your reference.

What can be the issue causing the output to over voltage?

--

Regards,

Kiran

  • 0
    TI__Expert 3525 points

    Hi Kiran,

    As you mentioned, the board/slave 1 channel worked before, but now hitting OVP at startup. Could you please check if any changes in between? such as operation condition, NVM config, loading, etc?

    When you saw the fault, was any loading at startup? Is this type of fault repeatable? 

    Can you also measure PWM, VSW and IOUT-REFIN on this slave1 channel together with VOUT? and zoom-in around start-up and fault event? 

  • 0 in reply to Qingquan Tang
    Intellectual 265 points

    Hi Tang,

    The issue got resolved.

    In between we have removed TPS53681RSBT IC in our board for debugging something. After mounting the IC we faced this issue.  Visually mounting of TPS53681RSBT was looking proper so we that there might be issue with something else. but we tried giving touch up to each pins of TPS53681RSBT. After that the issue got resolved. 

    I assume there might be issue with AVSP pins of TPS53681. After giving touch up it is working fine.

    --

    Thanks and Regards,

    Kiran

  • 0 in reply to Kiran Kumar R
    TI__Expert 3525 points

    Hi Kiran,

    Thanks for the update and glad you got the issue solved. Great!