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LTC4413 What happens if a voltage is applied to INB when ENBB is High?

Hi,

I have a question.
Please give me an answer.

About LTC4413,
If a charge is input to the INB while the ENBB is at the high level, the OUTB will be in the output state for a short time.

Is it normal operation?

・By the way, INA is 0V and ENBA is Low.

・ When INA and INB start up from the low state of ENBA and ENBB, the power is normally turned on (no short-time output).
・ If INA and INB are ON and ENBA and ENBB are set to High, they will be turned OFF normally. (No short-time output)

Best Regards,

Naohisa

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  • Hi, Aaron

    Thank you for your answer.

    We will answer the questions you have received.

    What is the slew rate of INB when it steps to 3V?

    → It starts up at a slew rate of 3.3V / 55us (actual measurement value).
    What kind of load is connected to the output?

    → SSD with SATA connection (before booting),
    The SD card (before booting), the previous Buffer-IC, and several logic ICs are connected.

    How much current does the load draw?

    → It is about 250mA. (Please refer to the figure below.)

    The enlarged one is also attached.

    Best Regards,

    Naohisa

  • Hi Naohisa,

    I used a DC839A to reproduce your results in the lab, so I can confirm this is normal operation.

    The LTC4413 is a low quiescent current part, but struggles with fast slew rates on INA/B. This could be related.

    The LTC4413-1 and LTC4413-2 are less sensitive to slew rate, and may address your problem. I’d check on the bench, but I do not have the parts on hand yet.

     

    Hope this helps,
    -Aaron

  • I received the -2 version.

    OUT is greatly reduced when INB is stepped.

    In both scopeshots below, INB is stepped with a slew rate of ~1V/ms.

    LTC4413

    LTC4413-2