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TPS7A91: Stability with lower Cin

Kazuki Itoh
Genius 9595 points
Part Number: TPS7A91

Hi team,

My customer trying to use TPS7A91 noticed that the their Cin=1uF is too small.
But, as it is close to the production, it's difficult to change the Cin to 10uF.
So, could you please help me to analyze how 1uF Cin affects the stability? Cout is 10uF.

  1. Can the output oscillate?
  2. Is TPS7A91 PSPICE transient model capable of simulate the transient ringing correctly?
  3. Other than the above, could you please suggest how the customer should test the device sufficiently?

Best regrads,
Kazuki Itoh

  • 0
    TI__Expert 8340 points

    Hello,

    1. The output can oscillate. 

    2. We definitely don't recommend using less than 10uF output and input cap for this part, as this is the minimum for this device. 

    3. I am looking into the PSPICE transient model and will get back to you as soon as I can.

    Best Regards,

    Hannah

  • 0 in reply to Hannah Grace
    TI__Expert 8340 points

    The PSPICE models are for basic LDO checks, but the actual feedback loops are not sufficiently modeled to a point that you could estimate transient ringing. If you have an EVM for this part, we recommend conducting a load transient for this part. If you do not have an EVM, please let me know and I can work something out.