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TPS51216: TPS51216 D-CAP Frequency

user5982066
Prodigy 150 points
Part Number: TPS51216
Other Parts Discussed in Thread: TPS51916
I would like to know about the specifications of TPS51216.
If the output ripple is too small, the D-CAP
The jitter may increase and the operating frequency may not be stable.
[reference]
  <www.tij.co.jp/.../jaja465.pdf>

Average: 450 KHz for our on-board power supply with a setting of 400 KHz
It seems that it may move at 2 MHz at the maximum
R)

[question 1]
In this case, what frequency range should I move?
[Question 2]
I think it has become unstable, but what kind of impact can be considered
Is it? It is understood that the specifications operate with changing frequency,
Please let me know.
  • 0
    TI__Mastermind 24075 points
    Hello,

    For DCAP model, if the output ripple is too small, the system may become unstable. I guess that's the reason you see Fsw become much higher.

    Question1:
    I don't have frequency range when the system becomes unstable.

    Question2:
    At higher frequency, the switching loss on the FET and the gate drive loss on TPS51216 will be higher, and both FET and TPS51216 may become hot and cause thermal issue.

    To solve this problem, can you make output ripple at VDDQSNS pin larger?
    Or you can consider TPS51916? This part can work at DCAP2 mode with low output ripple.

    Thanks
    Qian
  • 0
    Prodigy 150 points

    Hello,

    Thank you.

    >Question1:
    >I don't have frequency range when the system becomes unstable.

    what frequency range when the system becomes stable?

    Best Regards

  • 0 in reply to user5982066
    TI__Mastermind 24075 points
    Hello,

    It should be fine if the Fsw is in +/-20% range.
    In your design the Fsw is much higher than setting value, I suggest to increase the ripple injection.

    Or you can consider TPS51916. It offers DCAP2 mode which does not need external ripple injection circuit.

    Thanks
    Qian