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Find MOSFET equivalent

Discussion in 'General Electronics Discussion' started by HajimeK, Apr 23, 2014.

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  1. HajimeK

    HajimeK

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    Apr 23, 2014
  2. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    Nov 28, 2011
    I think this might be one for Steve.

    I found a data sheet and have attached it to this post. The basic information on the device is:

    STP7NB80FP: STMicroelectronics N-channel "PowerMESH" MOSFET in TO-220FP (full plastic enclosed package)

    Vdss(max): 800V
    Id(max): 6.5A
    Id (pulsed): 26A
    Ptot at Tc=25C: 40W (derate 0.32W/C)
    Rds(on): 1.2 ohms typical, 1.5 ohms maximum, at Vgs=10V
    Vgs(max): ±30V
    Vgs(th) 3V min; 4V typ; 5V max

    Here are the suitable replacements I could find on Digikey:

    1. Infineon SPA08N80C3: http://www.digikey.com/product-detail/en/SPA08N80C3/SPA08N80C3IN-ND/593246

    Equal or better in all important specifications except rated avalanche energy, single pulse - this one is rated for 340 mJ; the original is rated for 400 mJ. Lower Vgs(th) (3V typical vs. 4V typical) - probably not important.

    2. STMicro STP10NK80ZFP (SuperMESH): http://www.digikey.com/product-detail/en/STP10NK80ZFP/497-5972-5-ND/1578376

    Equal or better in all important specifications except rated avalanche energy, single pulse - this one is rated for 290 mJ; the original is rated for 400 mJ. Capacitances and charge figures are all somewhat higher.

    3. Fairchild FQPF9N90CT: http://www.digikey.com/product-detail/en/FQPF9N90CT/FQPF9N90CT-ND/1955342

    Also looks good. Higher avalanche specification. Slightly slower.

    4. Rohm R8008ANX: http://www.digikey.com/product-detail/en/R8008ANX/R8008ANX-ND/2791496
    Looks fairly good apart from the avalanche energy specification - only 4.2 mJ compared with 400 mJ for the original part!

    Many of the detailed specifications are beyond my understanding, and could be critical in your application (a switching power supply, I assume). Steve would be the best one to suggest the best alternative. I hope the research I've done will help him make a recommendation.
     

    Attached Files:

    HajimeK likes this.
  3. HajimeK

    HajimeK

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    Apr 23, 2014
    Thank you very much..
    Can't thank you enough since it has been month
    I have been searching for the equivalent..
    Anyhow..do you know what is the important characteristic in order to find the equivalent for this MOSFET?
    Yes I have been working on SMPS since I trace back that this component that has cause my fuse been blown..
    However this is only part of the problem I have another problem..
    Here is my other problem
    https://www.electronicspoint.com/threads/power-supply-problem-no-output.268370/
     
    Last edited: Apr 23, 2014
  4. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    Nov 28, 2011
    All of those four MOSFETs I suggested are equal to, or better than, the original device for the main specifications (maximum voltage, maximum current, etc) but there are other specifications that relate to switching behaviour that I don't know much about. That's why I have identified those possible replacements and suggested that Steve has a look at the data sheets and makes a recommendation.

    Steve is a regular contributor here, but he's probably asleep at the moment, as I should be :) Hopefully he will answer within 12 hours or so.
     
  5. HajimeK

    HajimeK

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    Apr 23, 2014

    Its good enough sir..Good to know..Again thank you.
     
  6. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    In order to determine whether that is a good replacement or not, you may need to tell us things like:

    1) what is it being used to do?
    2) what is the size and nature of the load?
    3) Is it being used for a switching or linear application?
    4) what drive is available for the gate?
    5) what frequency is it being asked to operate (or switch) at?
    6) are there any other constraints that are critical?

    If you're repairing something then you simply may not know some of these.

    The good news is that with time, newer mosfets get better, so a choice which may have been critical (or hard) when the device was designed may be simpler now.

    Given that it's in a SMPS, I'd probably want to be sure the gate capacitance, VGS(max) and rise/fall times are similar. RDS is probably not so important (but make sure it's not much higher). With a rating of 800V in this application, my guess is that avalanche operation would be unlikely.
     
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  7. HajimeK

    HajimeK

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    Apr 23, 2014
    Ahh....I see now sir..thanks for the info..Thank you very much now I know how to choose MOSFET equivalent..
     
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