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TPS23754-1: can replace TPS23754-1 from TPS23756

Tommy Tzeng
Genius 4805 points
Part Number: TPS23754-1
Other Parts Discussed in Thread: TPS23756, PMP11254

Hi Sir,

we directly change TPS23754-1 from TPS23756, but found that +12v output has jitter problem.

hope learn from you, what parts of the schematic need to be modified?

as attached file.

tps23756 +12v output waveform:

direct change TPS23754-1  12v output waveform:

  • +1
    TI__Mastermind 21320 points

    Hello, 

    The TPS23754-1 has a higher VC turn on threshold than the TPS23756. 

    Replacing the TPS23754-1 with the TPS23756 has no issues. Replacing the TPS23756 with the TPS23754-1 may have issues because of this. It will depend on the design. It looks like there is a lot of output capacitance for a 12V/25W diode flyback. The issue is probably due to the fact that the TPS23754-1 turns on later because it requires a higher VC voltage, which is changing the startup behavior. For reference, we have 44uF of output cap on our equivalent reference design (PMP11254), and you have 940uF. 

    Can you try reducing the amount of output capacitance?

    Can you share the transformer spec?

    If this post answers your question, please indicate so by marking this thread as resolved. Thank you.

     

    Regards, 

     

    Michael P.

    Applications Engineer

    Texas Instruments 

  • +1 in reply to Michael Pahl
    TI__Mastermind 21320 points

    Any updates here?

  • 0 in reply to Michael Pahl
    Genius 4805 points

    Hi Michael,

    sorry~ customer not reply yet. i will push again.