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Equivalent Part Number For PC817 Optoisolator IC

By on May 10, 2013

Optoisolator IC with the part number of PC817 can be easily found in many switch mode power supplies. If the Optoisolator IC have problem it would cause no power, power blinks, low power, power shutdown, intermittent shutdown and all sort of weird power problems. There is no doubt that the Optoisolator IC can be tested with multimeter but I found that the most accurate way is to direct replace the IC and retest. The reason for it this type of IC can breakdown when under load.

This means it will checked ok but failed when under full operating voltage. You can use PC123 part number as replacement but I found another part number that can also be used which is NEC2581A or PS2581A. Here is the link to the datasheet:

Note: The best is to use back the same original part number and if you could not locate the original part number then the only choice you have is to use the replacement number. This applies to all semiconductor devices.




  1. Amir Mukhtar

    May 20, 2013 at 1:32 pm

    Sir Jestine
    Thanks you for your Important and necessary information regarding solution of SMPS.
    i appreciate you in this regards. Thanks you again C/o. you are providing valuable teaching onlne with honesty.

    God Bless You.

    • Jestine Yong

      May 21, 2013 at 7:57 am

      Hi Amir,

      You are welcome.


  2. victor

    April 18, 2016 at 1:21 pm

    Dear jestine can i replace optoisolator pc123 with pc 817? thanks

    • Jestine Yong

      April 18, 2016 at 1:30 pm

      HI Victor,

      Yes you can.


  3. manjunath

    May 2, 2016 at 3:11 pm

    Hello will you please suggest the Equivalent for SMD PC817

    • John

      May 17, 2017 at 10:37 am

      Just use an equivalent DIP chip, bend the pins back so flush with IC bottom, trim to length & then mount as SMD

  4. N.Kesav

    October 29, 2017 at 7:55 pm

    I have mini smps range 14v 1.5ampere....
    Using for battery charger...
    Now the smps is not working...
    Smps Ac input bridge rectifier IN4007 diode got damaged..and i change it...
    N CHANNEL MOSFET also changed..

    But output is zero v...
    I check the gate voltage of mosfet...its showing negative voltage 290v dc.

    How to rectify this sir...
    Pls guide me sir

    • N.Kesav

      October 29, 2017 at 7:59 pm

      For activating N Channel mosfet. we need to give postive supply to Gate.
      But in this smps mosfet gate voltage is negative ....

    • Jestine Yong

      October 30, 2017 at 2:16 pm

      Hi N.Kesav,

      I suggest that you check all the components in the primary side and make sure no shorted output diodes at secondary side. If you replaced the FET this means the Power IC (if have) you also need to replace and retest.


  5. thisara vidurangalal

    April 27, 2019 at 10:15 am

    Dear justin plz tel me
    hpc922-1 optocoupler equelents

    • Jestine Yong

      April 30, 2019 at 1:44 pm

      Hi Thisara,

      Sorry no info on such part number and equivalent.


  6. Victor

    November 29, 2019 at 9:23 pm

    Is pc817 the same with pc123, or what is the differences between pc123 and pc817?

    • Jestine Yong

      December 3, 2019 at 8:36 pm

      Hi Victor,

      They are the same.



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