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CSD18537NQ5A: Gain corner frequency

Expert 1995 points

Replies: 4

Views: 1016

Part Number: CSD18537NQ5A

Hi TI,

Can you determine the gain corner frequency of a TI FET(CSD18537NQ5A)?

I have the following problems.

PD 'TPS23753' review. (The circuit diagram refers to the TI 'PMP5220' reference.)

1. Good / Issue Transformer + SiR422DP

2. Good / Issue Transformer + CSD18537NQ5A

Thank you.

Thanks and Best Regards,

===========================================

BJ Han.

===========================================

4 Replies

  • BJ,
    I have reached out to our applications team. I will let you know when I have a reply.

    Best Regards!

    Brett Barr

    Product Marketing Engineer

  • In reply to Brett Barr1:

    BJ,
    The apps team commented that this appears to be a system level parameter.

    Are you using the FET as an amplifier? The "s-parameters" you are inquiring about are typically not provided for power MOSFETs like our own, and I do not believe we have the capability to characterize them.

    I couldn't find PMP5220 on the web. Did you have a link to the reference design?

    Best Regards!

    Brett Barr

    Product Marketing Engineer

  • In reply to Brett Barr1:

    BJ,
    I may have spoken too soon here. One of our apps engineers recently worked with TI sales on this very issue. It would be an awful coincidence if you weren't working with the folks.

    But regardless, the issue came down to not the transformer, but rather proper FET selection. The CSD18537NQ5A is a better FET for this application it seems. The Vishay part has a poor charge ratio (Qgd/Qgs) that makes it not ideal for this application. The lower threshold also may present a problem for this type of "self driving" application.

    Best Regards!

    Brett Barr

    Product Marketing Engineer

  • In reply to Brett Barr1:

    Dear Brett,

    Thank you for your attention and support.
    This problem was solved with TI FET.

    It is stated that if the gain corner frequency of the FET is smaller than the resonance frequency of the external resonance circuit in the document which is related to the problem, the phase shift oscillation does not occur.

    Since MOSFET replacement alone does not cause any problems, it will help us to interpret our problem.

     

    Thanks and Best Regards,

    ===========================================

    BJ Han.

    ===========================================

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