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AMC1200: Abnormal output analog pulse at the moment of power shutdown

Part Number: AMC1200

We use AMC1200, at the moment of power shutdown, output abnormal analog pulse.

Below is my test condition:

1. Isolated 5V power supply at both ends of the chip

2. Short the differential input pins 2 and 3

3. Disconnect the rear differential operational amplifier circuit and delete R7 and R10, as shown in the schematic diagram:

Test results: at the moment of power failure, amc1200 differential output pin 6 and pin 7 have isolated pulse analog voltage output

  • Which supply voltage is shut-down? The input or output supply voltage?

    Why do you disconnect the differential amplifier from the output of AMC1200? What would you see at the output of U13 during shut-down?


  • Hi,

    What is the input common-mode voltage during this test? I see that there is a resistor, R112 in between the negative input and GND. 

    I would suggest tying the inputs directly to GND to avoid input voltage-common mode limitations.

    The output common-mode output voltage is typically 2.55V when powered by 5V on VDD2. I see in your test that the output voltage is held at 0V before the event occurs. 

    Can you please show a waveform of the power supply shutting down and the other output?