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CSD95490Q5MC: TAO/FLT pulled down during startup

Yuxiang Shi
Prodigy 40 points
Part Number: CSD95490Q5MC

Hi,

The TAO/FLT pin was pulled down during startup, causing it not able to start. The Lset resisitor (154k for 202nH) and REFIN pin (1.7V) are all correct. Cannot figure out the reason. Can some help me out asap? Many thanks.

Schematics

Best,

Yuxiang

  • 0
    TI__Expert 3525 points

    Hi Yuxiang,

    I cannot see the schematic you attached.

    But could you please verify the VDD voltage? If VDD is under voltage, it is possible that TAO is pulled low to flag the fault. Could you please also verify the soldering and pin connection for the power stage? If there is connectivity issue, it may also cause TAO to be pulled low.

    Best,

    Qingquan

  • 0 in reply to Qingquan Tang
    Prodigy 40 points

    Hi Qingquan,

    VDD is 5V, and is good as shown in the figure below. I believe the connection is good, as this issue showed on multiple units. And at low voltage e.g. 8V, it can startup (though may not be always). 

    Best,

    Yuxiang

  • 0 in reply to Yuxiang Shi
    TI__Expert 3525 points

    Hi Yuxiang,

    I couldn't see the schematic you attached. Could you please try again?

    If the issue happened on one power stage, the TAO will be pulled low and affect all the other units (I assumed all TAO signals were tied together)

    Best,

    Qingquan