Problem of ADUM1411-Low Level rise to >1V when 3 ADUM1411 was connected to MCU

I came across a problem when testing ADUM1411.

Every ADUM1411 connect to MCU will make the low level voltage in Vin Din of MCU (connect to VIC pin of ADUM1411) rise (The high level voltage maintain 5V). 

When I connect 1 / 2 / 3 ADUM1411 to MCU, the low level will rise to 0.3 / 0.9 / >1 V. And then MCU could not recognize the low level voltage.

Below I show the schematic diagram & timing diagram when 0/1/2/3 ADUM1411 is connected to the MCU. Tks for your help!

No ADUM1411 was connected to MCU

One ADUM1411 was connected to MCU

Two ADUM1411 was connected to MCU

Three ADUM1411 was connected to MCU

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  • Hi Alex,

    The ADuM1411 has CMOS level output, and I think it might be different from ADCs. Could you just use one ADuM1411 connecting to the MCU(No ADCs) and check the low output voltage?

    We don't recommend to connect multiple ADuM1411s' outputs to a bus line, it would bring risks if one outputs high and the other has low output level.

    Regards,

    Neil

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