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TPS25940: Questions about super cap charging application

Alec Chen
Intellectual 730 points
Part Number: TPS25940

Hi, Sir

Our customer want to use TPS25940 with super cap charging application base on TI application note as below:

slva920.pdf

However, we have a little question Cdvdt parameter. In TPS25940 spec , the Cdvdt recommended operating conditions us shonw max 470 nF:

but in the application note, it shows that we would have to use a larger capacitance. please see as below(RD is choosing 5F super cap)

   

So, RD have two questions needed you help give us some advises:

1. Is there is any risk based on the super cap charging application if we use the capacitance value on Cdvdt ?

2. Is TPS25940A or L suitable using for 5F super cap charging application of slva920 data

Above, please kindly help us and hope to hear form you soon.  if there is any question, please feel free to let me know

Cheers

Alec

  • 0
    TI__Guru** 105361 points

    Hi Alec,

    Thanks for reaching out and your interest on TPS25940.

    The max CdVdT limit is mainly to discharge the CdVdT capacitor before the auto retry interval of 128ms. Otherwise, there's no limit on max Cdvdt. You are allowed to choose bigger capacitor at dVdT pin to charge the super capacitor at a slower rate.

    TPS25940A is recommended to ensure startup even in case of under sized  CdVdT capacitor.

    What is the application ?

    BR, Rakesh