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About UC3842 PWM IC

By on October 13, 2008

This UC3842 IC is one of the most famous PWM IC use in SMPS circuit. It can be found in many electronic equipment ranging from Monitor, TV up to computer power supply. Do you know that not all part number of UC3842 can be 100% substitute with another similar part number? Lets take this for example, you found the part number of SG THOMPSON UC3842 IC have problem and your supplier give you IP3842 while others give you HA17384 and Motorola UC3842.

Do you think that all these IC spec is the same? Not really until you have tested out on the equipment you repair. I came across Monitor produced hissing sound and power blink when different number used. After putting back the exact part number, all of these symptoms gone! Now not all equipment have the same problem-you just have to test it out yourself. Hope you can learn from my experience and if possible get back the same part number.



  1. V RAMAN

    January 7, 2009 at 6:53 pm

    working of UC3842 pwm IC

  2. admin

    January 8, 2009 at 10:19 pm

    Hi Raman,

    May i know what is your question?


    • Ravi Verma

      August 26, 2016 at 6:11 pm

      Is ic 2263 better than 3842 if yes in what way

      • Jestine Yong

        August 27, 2016 at 9:10 pm

        Hi Ravi,

        I have not used this IC before thus I can't give any comment on.


      • vijay

        May 15, 2019 at 12:53 am

        2263 have a output circuit called totem. It helps for fast swiching of mosfet. So reducing switch losses and EMI.

  3. manishgovindan

    February 23, 2009 at 2:14 am

    can you please tell me if there is an ic available which generates SPWM using unipolar switching which can be used for a single phase inverter

  4. admin

    February 23, 2009 at 11:30 am

    Hi Mani,
    Sorry no information on that.


  5. kaleem

    October 30, 2009 at 10:56 pm

    i want to know that which ic can substitute uc3842 reply me soon thanking you

  6. admin

    October 31, 2009 at 4:29 pm

    Hi Kaleem,
    This IC is easy to get thus need not waste time to find substitution. By the way there is no substitution part number for it.


  7. Nelson R. Pagdanganan

    June 17, 2010 at 10:33 am

    Do you know what's the best replacement for OB2263AP PWM IC?

  8. admin

    June 18, 2010 at 1:49 am

    HI Nelson,

    Sorry no info on this. Usually it is very hard to find replacement for power ic. You may try to contact this seller:


  9. Amir Mukhtar

    February 17, 2011 at 5:12 pm

    Dear Sir,
    thanks you for your positive guidance and support to us.
    God Bless you Sir,

    Amir mukhtar

  10. sandeep

    June 5, 2011 at 4:14 am

    I am using SMPS in my weighing m/c. one lot of our vendor supply had problem.
    It's getting off After one minute of switch on. What will be the problem in which part?

  11. admin

    June 5, 2011 at 11:12 am

    HI Sandeep,

    I suggest that you check the output of the power supply and make sure it is good and stable.


  12. Amitha

    November 9, 2012 at 11:33 pm

    can you differntiate the difference beween the variation of the IC like UC3842, UC3842A, UC3842B

    • Jestine Yong

      November 12, 2012 at 8:30 pm

      Hi Amitha,

      I can't differentiate it because all the datasheet looks the same. However,in some power supply circuit it will only work perfectly well when the original version is used. If you use different version it may cause slight output noise and will affect the equipment performance.



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