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  • What happens if schottky diode is replaced by general purpose diode?

    Shyamsundar

    Member

    Updated: Oct 20, 2024
    Views: 1.1K
    Hi all,

    I've uploaded one schematic.. please go through the attachment. My question is:
    In the schematic, to the VDD pin of the IC, diode D2 is connected which is of schottky type. what happens if general purpose rectifiers like 1N4007 is used in that place? what is the purpose of using diode D2 in that place.. Can anyone tell me please.?
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Replies

  • Scorpion007

    Member • Dec 26, 2012

    may be it is concerning with frequency of current because Schottky diode design to work in high frequency current ( even 300 Mhz frequency) but normal PN junction diode do not works in high frequency. It is my opinion.
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  • Shyamsundar

    Member • Dec 26, 2012

    Scorpion007
    may be it is concerning with frequency of current because Schottky diode design to work in high frequency current ( even 300 Mhz frequency) but normal PN junction diode do not works in high frequency. It is my opinion.
    ok, but why diode is needed in that place?
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  • Harshad Italiya

    Member • Dec 26, 2012

    Shyamsundar
    ok, but why diode is needed in that place?
    As said by #-Link-Snipped-# its for high frequency purpose as schottkey diode can response on high frequency another reason is to prevent the supply goes back to mains. As diode cathode is connected to VDD it will give you provision to do not flow voltage in reverse direction.
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  • rikil

    Member • Dec 27, 2012

    Technically, Schottky diode has very low reverse recovery time as compared to normal rectifier diode. Your circuit, which I suppose is SMPS, works on may be more then 500Khz. So in that case at switching side Schottky diode is needed. If you see, on power side, normal diode is used.
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  • Shyamsundar

    Member • Dec 27, 2012

    rikil
    Technically, Schottky diode has very low reverse recovery time as compared to normal rectifier diode. Your circuit, which I suppose is SMPS, works on may be more then 500Khz. So in that case at switching side Schottky diode is needed. If you see, on power side, normal diode is used.
    SMPS operating frequency is 115kHz, What is the output response if it is replaced by power diode?
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  • [Prototype]

    Member • Dec 28, 2012

    Shyamsundar
    SMPS operating frequency is 115kHz, What is the output response if it is replaced by power diode?
    Simply speaking, your SMPS will fail because normal diode won't be able to switch in the given required time. Now with fail, I don't mean it'll not start. It will just produce a unreliable output with glitches. Not to mention, the diode will burn eventually after sometime. If you place a higher rating diode, it won't burn, but still the output will be distorted.
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  • Jeffrey Arulraj

    Member • Dec 30, 2012

    Shyamsundar
    SMPS operating frequency is 115kHz, What is the output response if it is replaced by power diode?
    Schottky is famous for its switching speed try to use it diodes even very fast diodes have high response time which will not support 115kHz any time so it is a poor choice you are making if you swap your schottky
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  • arunchary

    Member • Jan 31, 2013

    surge current concept is not holds good normal diode compared to schottky diodes...and as well as higher amount of currents can be applicable in this type only with higher frequencies .
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  • sangram shelake

    Member • Jul 24, 2018

    I used fast switching response diode which is taken from Crt TV main board in the place of one of two shottky barriers diode at the secondary side of 13v DC output smps of led TV power board and it became successfully gives 13v DC output.


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