Schottky Diode

Discussion in 'General Electronics Chat' started by RRITESH KAKKAR, Aug 29, 2010.

  1. RRITESH KAKKAR

    Thread Starter Senior Member

    Jun 29, 2010
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    I have SMD IC & on searching It in Google I found It Belong To Shocky+...
    The number of it is STS4DPFS30L (MOSFET PLUS SCHOTTKY RECTIFIER) pLs Explain It As I have study Shocky diode in class But here i am not Getting It........!:confused:
     
  2. retched

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    Dec 5, 2009
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  3. RRITESH KAKKAR

    Thread Starter Senior Member

    Jun 29, 2010
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    I have study it but this ic I am not getting that's why I was Asking for help........!
     
  4. tom66

    Senior Member

    May 9, 2009
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    A schottky diode is like a normal silicon diode, except in four important ways:

    • The junction is not semiconductor-semiconductor (e.g. PN) it is a Schottky barrier junction.
    • Forward voltage drop is low - usually 0.25V to 0.5V. In switching mode power supplies, the difference between a silicon diode (0.6V - 1.0V) conveys much greater efficiency and thus lower cost overall (even though the diodes are more expensive) because less thermal management is required.
    • They can switch very fast. Much faster than typical silicon diodes. This also means greater efficiency and higher operating frequencies for SMPS designs.
    • Peak inverse voltage is usually limited. While silicon diodes barely go below 50V PIV (peak inverse voltage), Schottky diodes come as low as 20V, and possibly lower
    Most of this was sourced from http://en.wikipedia.org/wiki/Schottky_diode

    I highly recommend you 'Wikipedia' it before you ask... it will get you your answers much quicker.
     
  5. Potato Pudding

    Well-Known Member

    Jun 11, 2010
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    I think his question is why they added the Schottky to the MOsFET. It is to protect the Mosfet from inductive CEMF kickback that could destroy the MOSFET with high reverse voltages.
     
  6. tom66

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    May 9, 2009
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    If he's talking about the body diode, it's an inherent part of the MOSFET and it comes from the internal structure. IIRC, having a body diode is more preferable to having a parasitic transistor, which could make the FET uncontrollable. The body diode means the FET cannot block reverse voltages.
     
  7. RRITESH KAKKAR

    Thread Starter Senior Member

    Jun 29, 2010
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    Pls tell Clearly i am Not Getting You, I want to tell That This SMD ic i have Taken Out From My Tata Sky set Of Box..., & waiting For Understanding It Pls help ...........!
     
  8. Potato Pudding

    Well-Known Member

    Jun 11, 2010
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    Well if you have taken a SMD Fet out of your cable box then your cable box is going to be broken.

    It might have been part of the power supply but this is not going to be easy or even possible for us to help you fix.

    We have already answered your questions and I don't see a new question.
     
  9. marshallf3

    Well-Known Member

    Jul 26, 2010
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    So now you're tearing stuff apart then asking what the parts are? Why would you do that?

    As mentioned above, and in the responses to several of your other threads, the answers to the simple questions you seek are in Wikipedia and the e-book we keep referring you to but - as also mentioned - until you get a grasp on the first few years of electronic theory, and physics, chemistry etc not much of anything you read or anything that we write is going to make much sense either.
     
  10. RRITESH KAKKAR

    Thread Starter Senior Member

    Jun 29, 2010
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    I want to tell That Box Was Not working that's Why I have taken Out SMD Component.

    I have Study Shocky Diode That are use for High Freq. & switching time (more than 10Mhz) But, I want To Know I have seen It Ckt. But not Understanding It Working
    as I have Use zener & Simple Junction Diode & Solder It More Than 150pc. On small PCB.
     
  11. kubeek

    AAC Fanatic!

    Sep 20, 2005
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    So what is the question?
    Man, can´t you just read the article on the schottky diode that Retched referred you to?

    In a nutshell, Schottky is a faster version of the standard silicon diode, it has lower forward voltage drop, but also usually lower maximal reverse voltage than a standard diode.
     
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  12. marshallf3

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    Jul 26, 2010
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    If you want to troubleshoot something you need things like a schematic, a good volt-ohm meter and usually an oscilloscope as well so you can pinpoint the problem down to the component that's at fault. If you try "shotgunning" (old terminology) trying to repair things it usually ends up costing a lot of money and by Murphy's law it's usually one of the last parts you replace.
     
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  13. RRITESH KAKKAR

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    Jun 29, 2010
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    I am gone through it circuit & not able to understandi it ckt. pls You go through it PDF & Explain Me.
     
  14. kubeek

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    Where is the PDF that you are talking about?
     
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  15. RRITESH KAKKAR

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    Jun 29, 2010
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    You Will get it on Google, While searching on it name (Ic number)......1
     
  16. marshallf3

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    If it's the MOSFET with the integral diode portion mentioned you already got a lot of valid explanations.

    2nd year here too, after things like basic English language studies, couple of semesters of physics and chemistry to understand electrons and electron flow, semiconductor technology etc:
    http://www.tech.okstate.edu/
     
    Last edited: Sep 2, 2010
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  17. atferrari

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    Jan 6, 2004
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    It is strange the way you use capital letters in the middle of a sentence. What is the use?

    Annoying to say the least.
     
    Last edited: Sep 3, 2010
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  18. kubeek

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    The pdf he is talking about is here. The device is most probably made for use in switching power supplies, where you use the transistor as a switch and the schottky as a recovery diode.

    The circuits at the end of the pdf are test circuits that were used for getting the parameters stated in the PDF. They are not meant as typical use examples.
     
    Last edited by a moderator: Sep 3, 2010
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  19. RRITESH KAKKAR

    Thread Starter Senior Member

    Jun 29, 2010
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    ok, I am goon through the link & that my question i can't understand the circuit using symbol pls now help....!
     
  20. gootee

    Senior Member

    Apr 24, 2007
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    That IC has two completely-separate components in it.

    The Schottky diode has each lead connected to two pins of the IC, probably for higher current-carrying capacity.

    What's not to understand? It's a lot like a regular diode, but with a smaller voltage drop. This one should let current flow into IC pins 1 and 2 and out through pins 7 and 8, but NOT in the other direction.

    You could probably test it with a multimeter, using the resistance (or "continuity", or "diode") test mode, trying it in both directions. One direction (i.e. pin 7 or 8 positive/red probe and pin 1 or 2 negative/black probe) should have a LOT more resistance than the other direction.

    If you have an oscilloscope, you could also test it with the "quick and dirty curve tracer", using a small transformer (or signal generator) and a couple of resistors, like they describe at: http://www.repairfaq.org/REPAIR/F_semitest.html#stqdc .

    A simple "continuity" test should also work, in one direction only, assuming it uses a voltage that's above the Schottky's rated forward voltage of 0.51 Volts. A battery and a small lamp or LED circuit would also work, for that test.
     
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