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Overshoot at rising edge of ADUM 6028

naohisa
on Jul 8, 2019

Hi, I would like to use ADuM6028.

So, I have a question. Please help me.

Question:

Please let us told about the overshoot at the rise of the ADUM 6028 output.

I made a board using ADuM6028 referring to the circuit and layout of the evaluation board.
The specifications are Vin = 5V, Vout = 5V, Iout = 13mA.

When the characteristics were confirmed, the overshoot at startup exceeded 6V.


There are the following characteristic graphs in D/S.
I think that it is one of the causes that the load is light, but I think that it is big to exceed 6V.

I did some experiments.
If the rise on the input voltage side is made slow (about 20 ms),
The overshoot could be made less than the D/S characteristics.

Are there any limitations, such as rise time, on the input voltage side?
Or is there a sequence of power supply to each pin?

Best Regards,

Naohisa

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    •  Analog Employees 
    on Jul 15, 2019 5:34 PM over 1 year ago in reply to naohisa

    Naohisa-san: I asked the designer and here is his response:

    The overshoot in adum6028 is caused due to the duty cycle mismatch between soft-start mode and loop control mode.

    This overshoot will be larger when loading is very light, but I am a little surprised it will exceed 6V.

    Based on the datasheet, it should be smaller than 6V.

    To reduce the overshoot, to increase the power up time will be one solution to reduce the overshoot because adum6028 start to work when VDD is larger than 4.2V and the output power is smaller when VDD=4.5V or smaller than 5V.

    No other option for PDIS or VDDP sequence to reduce the overshoot.

    Regards, Brian

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