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DCPA10505D: Regarding Soft Start operation

Part Number: DCPA10505D
Other Parts Discussed in Thread: DCPA10505

Hi Team,

I would like to know about the Soft Start definition in the datasheet.

(1) “a delay of typically 10 ms before the output voltage begins to rise”

  Is this an understanding of the pink part of the figure?

dcpa10505_DS.pdf

(2) What is the definition of “the soft start time is typically 5 ms”?

  Is it ok to understand that the rise time of the output voltage (time to reach 10% ⇒ 90%) is 5ms in typ value?

  Please illustrate if possible.

(3) What are the numbers (1) and (2) above for DCP010505DBP?

  Is 0ms for (1) (no delay ≒ no intentional delay)?

Best Regards,

Kenji

  • Hi Kenji,

    For the DCPA10505;

    1) Yes, there is typically a 10ms delay before the output voltage begins to rise after a the input voltage is above the +Vs UVLO (2.25V)

    2) The soft-start time is the time it takes for the output voltage to rise from 0V to it's regulation voltage. 5ms is the typical value.

    3) These values are not defined for the DCP010505. This device does not have soft-start so the output voltage will try to ramp up very quickly, leading to large inrush current. This may cause the output voltage to rise monotonically. See figures 29 - 31 in the datasheet.

    Thanks, Jason