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ISO7220M: Why the output of ISO7220 is always high regardless of the input high or low?

Part Number: ISO7220M

Hi Team,

My customer is using ISO7220M, and they meet a weird issue. The output of ISO7220 is always high regardless of the input is high or low, can you help suggest why this issue comes from? Below is their test conditions.

1. Test 1: Connect input to left side GND, and read ISO output with FPGA, but always read out high.

2.Test 2: Disable isolation by connecting two side GND together, then use FPGA GPIO_1 give ISO7220 input, and read ISO7220 output to FPGA GPIO_2. However, the output of ISO7220 is always high regardless of the input is high or low

Thank you!

Best regards

Yunjing

 

  • Hi Yunjing,

    Thank you for posting to E2E! ISO7220M has a failsafe state of logic HIGH on the outputs, so if input signals are not successfully transmitted across the isolation barrier, the output will remain a constant HIGH.

    Both input-side and output-side power supplies must be between 3V and 5.5V in order to transmit valid signals across the isolation barrier. Please verify the voltage levels on pins 1 and 8 are between these levels, and feel free to share a schematic of the isolator circuit.


    Best,
    Manuel Chavez