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LP2985: Output voltage startup timing

Daisuke Higa
Genius 4505 points
Part Number: LP2985


Tool/software:

Hi support team all.

My customer is having issues with the output voltage startup timing.

Could you please help me resolve this?

As shown in the waveform data below, the 36th week of 2022 product had a time delay of about 200ms from the input voltage rising to the output voltage starting to rise.

The 2024 manufactured product has almost no delay.

Is this due to the Output Pull-down circuit added in the PCN issued in December 2022? (PCN#20221213002.0)

It has already been confirmed that about 500 pcs of the 2024 products are all the same.

Could you tell me why the startup time has been shortened so much?

Best regards,

Higa

  • 0
    Genius 4505 points

    Hi support team.

    Do you have any update?

    This issue is urgent, so we would appreciate a response as soon as possible.

    Best regards,

    Higa

  • 0 in reply to Daisuke Higa
    TI__Genius 15720 points

    Hi Higa,

    It's possible that the change in startup time might be due to the 2024 material containing the new silicon (as described in the 2022 PCN above) rather than the legacy design, but Figures 8-17 through 8-24 show both the new and legacy chips having startup times less of a few hundred microseconds, not the 200ms shown above.

    Can you clarify what the red and green traces are in your oscilloscope capture above? Would it be possible to provide the customer schematic for their circuit containing the LP2985?

    Best Regards,

    Alex Davis

  • +1 in reply to Alex Davis
    Genius 4505 points

    Hi Alex-san

    Thank you for your reply.

    Let me confirm to my customer.

    Do you think a 200ms delay is abnormal?
    I think it is abnormal, but my customer says they've had this delay for a while. I'll check to see what the facts are.

    Best regards,

    Higa

  • 0 in reply to Daisuke Higa
    Genius 4505 points

    Hi support team.

    This thread will be closed for now as it will take some time to investigate.
    Thank you for your support.

    Best regards,

    Higa