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ISO1212: Input with positive or negative voltage

Brian Wang0928
Genius 11640 points
Part Number: ISO1212
Other Parts Discussed in Thread: ISO1211

My customer would like to find a digital input with negative or postive 24V input and below requeiremnts:

After testing, it looks the ISO1212 can not offer the -24V input, right? any workaround solution. pls find the schmatic here.

1. Delay time <3uS

2. Support COM 0V or 24V

3. Follow IEC61131-2 type compliant

  • 0
    TI__Intellectual 2200 points

    Hi Brian,

    Your observation is correct. The ISO1212 blocks -ve voltage.

    The following application circuit can be used for bi-directional operation. It is shown for ISO1211, but can be used with each channel of ISO1212 as well. In this case, the COM can be connected to 0 or 24V.

    BAT54CLT1G are low cost Schottky diodes - available in a dual package.

    Rgds,

    Anant