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TPS22924C: Vout at start-up

Yuto Sakai
Mastermind 6100 points
Part Number: TPS22924C
Other Parts Discussed in Thread: TINA-TI

Hi,

Could you tell me the operation of the TPS22924C at the start-up.

When Iout is small, the waveform appears as if the output voltage at the start-up time is raised.

Could you tell us the reason for this behavior?

It was also reproduced by TINA-TI, so I attached it below.

Best Regards,

Yuto Sakai

  • 0
    TI__Genius 15770 points

    Hi Yuto,

    The TPS22924C has a quick output discharge (QOD) feature that keeps VOUT pulled down when the device is not turned on. However, looking at section 9.3.3 in the datasheet, you will see this note:

    "The output pulldown is active when the user is turning off the main pass FET. The pulldown discharges the output rail to approximately 10% of the rail, then the output pulldown is automatically disconnected to optimize the shutdown current."


    If the load current is too small to keep the output pulled down, then the QOD may not fully discharge the output before turning on the device. Do you see this behavior in the lab?

    Also, the TPS22924C has a next generation device, the TPS22925C. This device is higher performance and the QOD will stay active to pull down the output to 0V. Because the two devices are pin-to-pin, it would be worth trying the TPS22925C instead.

    Thanks,

    Alek Kaknevicius

  • 0 in reply to Aleksandras_Kaknevicius
    Mastermind 6100 points

    Hi Alek-san,

    Thank you for your reply.

    In the area where the output voltage at the start-up time is raised,

    it is not understand that the output voltage rises even when the device is disabled.

    I have confirmed this behavior in the lab.
    I'd like to send a waveform, could I send it by e-mail?

    Best Regards,

    Yuto Sakai

  • 0 in reply to Yuto Sakai
    TI__Genius 15770 points

    Hi Yuto,

    I have sent you a private message with my email, feel free to send me the scope shot.

    Thanks,

    Alek Kaknevicius