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TPS734: vs TPS78401Q

Part Number: TPS734
Other Parts Discussed in Thread: TPS784-Q1, TPS784

Hey team,

I had a customer that was looking at these two parts and doing a brief comparison of the two. They highlighted the difference in startup time specified between the two datasheets.

I see that the TPS78401 goes to 95% of Vout rather than 90%, but the datasheet states that the start time for the TPS73401 is <60us while the TPS78401Q is ~500us.

What is the reason for this large difference? We are looking at this as a possible replacement part for constrained inventory.

Thanks,

Cameron

  • Hi Cameron,

    Some devices have built-in soft-start that slows the ramp time for a more controlled startup that limits inrush current, and some devices also have a delay after the supply comes up for a similar effect.

    In this case the TPS784-Q1 has an internal soft-start:

    Regards,

    Nick

  • Hey Nick,

    Good to hear from you! One quick follow up question prior to closing the thread - I assume we can't disable the internal soft-start time? I only see it mentioned in the header of the datasheet for the TPS784.

    Thanks,

    Cameron

  • Hi Cameron,

    Likewise!

    That is correct. There's no way to disable the internal soft-start.

    Regards,

    Nick