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ADuM1200 drive MMBF170L mosfet


My original designing use 5V optocoupler to finish the isolation function, optocoupler output drive the MMBF170L mosfet at ON or OFF state with very low frequency.

Now, I feeling ADuM1200 chip also can finish the same function, the better thing is this way need less current than optocoupler.

Due to I never use ADuM1200 chip to drive the MOSFET, I have a little bit worry about whether it can work well.

Could you helps to take a look it, whether it is a normal usage without risk.


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  • Hi, Dave,

    Very thanks for you kindly reply.

    And, I am confusing one item.

    Here is my circuit, replace opto-coupler with our ADuM1200 chip. Isolate LOGIC side(VDD1 side) and FIELD side(VDD2 side).

    The result I needed is:

    The Q9 on/off frequenty is very low, most of time, Q9 keep ON or OFF state without no change, only in some time, Q9 need change state once, but,

    When logic side input 1, field side need output 1.

    When logic side input 0, field side need output 0.

    When VDD1 or VDD2 failed, output need keep 0.

    Then, I found use ADuM1200 is incorrect, because when VDD1 failed, output keep 1.

    Then, I found use ADuM1210 can solve this, when VDD1 failed, output keep 0.

    But, Please take a look the under Truth Tables.

    If VDD2 failed, output state is "Indeterminate", I can't understand the meaning of it, is it possbile outout is 1 or 0? If so, looks I can't use this chip, due to I need keep outout to 0, 1 will generate very bad result.

    Could you helps to analysis whether my understand is correct.

    And whether we have one chip can fit my requirement.

    Or, whether it is not a good usage I use this chip on here, you know i want to replace opto-coupler with i-coupler.

  • Hi Weidong:

    When VDD2 is below UVLO point, the output is high impedance. By adding 10kohm pull down resistor, we can get a logic L output.