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TPS923653: CC/CV backup capacitor charger

nickerchen
Prodigy 20 points
Part Number: TPS923653

Tool/software:

Hi team

I want to use a TPS923653 to charge a 1000uF 50V capacitor as an energy source for emergency shutdown of a customer application.
Input voltage can be between 18V and 45V, but it won't change during operation.
I'm planing to charge with around 700mA or less.

Once charged, during normal operation the capacitor will be held at its rated voltage of 50V in CV mode.
It is discharged when the supply voltage fails, to supply the system for around 70ms.
During normal operation the rest of the system runs from the Input voltage directly, not from the capacitor voltage.

I think the TPS923653 would be an ideal candidate to do so. What do you think ? Any stepping stones ?

For the circuit design I would be glad to have a simulation model. SPICE / PSPICE, if available, or the SIMPLIS model I read about here in the forum.

Thanks for your help

  • 0
    TI__Mastermind 23190 points

    Hi nickerchen,

    May I understand what is the minimum voltage of the capacitor when you are going to charge it?

    Best Regards,

    Steven

  • 0 in reply to Steven Li
    Prodigy 20 points

    Hi Steven

    0V
    I later realised this will create a large inrush current, which is probably why you ask.
    Any suggestions on how to avoid that ?

    Best Regards,
    Urs

  • 0 in reply to nickerchen
    TI__Mastermind 23190 points

    Hi Urs,

    nickerchen said:
    0V
    I later realised this will create a large inrush current, which is probably why you ask.

    You are correct. This is the reason why I asked the above question. In this condition, you cannot use TPS923653 here as the current will be out of control when the output voltage is lower than the input voltage.

    This is caused by the boost topology. I think you may need a buck-boost topology here (Although TPS923653 can support buck-boost topology, it cannot be used here due to its voltage rating).

    Best Regards,

    Steven