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ISO1228: Power OK to PLC

Chirag Panchal2
Prodigy 100 points
Part Number: ISO1228
Other Parts Discussed in Thread: ISO7741, ISOM8710, ISO1212, , ISO7740, ISO7741EVM

Tool/software:

I am using three AC/DC programmable power supplies (HDS3000-12) in parallel for my application. Each power supply provides a "POWER OK" (POK) signal, which is connected to the PLC digital input module (AXL SE DI16/1 NPN). However, due to differences in grounding, I am unable to reliably detect feedback signals (True/False).

I believe that a digital signal isolator is necessary to address the grounding issue while maintaining electrical isolation. Could you provide advice or suggest a suitable circuit design for this purpose? You can also suggest any other option or IC that can be usable. 

1. PLC Di module AXL SE DI16/1 NPN - Digital module

2. Power Supply  HDS3000-12 

  • 0
    TI__Mastermind 22435 points

    Hello Chirag, 

    Thank you for reaching out and considering our isolation solutions. Please see my comments on the following options.

    1. Digital isolators, like ISO7741, are recommended for 0-5V logic applications. It looks like these will be the best fit for your application. Otherwise:  
    2. Opto-emulators like ISOM8710 can be used if the signal needs to be powered off the input. 
    3. ISO1228 or ISO1212 can be used for 24V digital inputs, if applicable. 

    Let me know if you have further questions on any of these. 

    Best,
    Andrew

  • 0 in reply to Andrew J
    Prodigy 100 points

    Hi Andrew, Thank you for your reply. I agree with your suggestion. I think Digital isolator - ISO7740 would the best solution for the my design with a spare channel. Do you have any example design /circuit? I can not find anything on the TI website.

    Thanks and regards, Chirag

  • 0 in reply to Chirag Panchal2
    TI__Mastermind 22435 points

    Hello Chirag, 

    The ISO7741EVM found on the product page will be the best reference for to the IC. We also have TIDA-00118 reference design | TI.com for a PLC reference. 

    Best,
    Andrew