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    SMPS Through Hole to SMD Package

    Hi all,
    I have a 12V-1 Amp SMPS design which i assembled it using through hole components. all the resistor are in 1/4 watts, zener diode are in 1/2 watts. (Circuit Attached)
    but now the same SMPS Design i converted in SMD Package (only Resistors and diode in 1206 package, and rest of all are still in through hole package)
    so now when i ON the SMPS with SMD Package, The iC MJE13005 burns out in just few seconds and SMPS stops working, but the same when i ON the SMPS with through hole package, it works well even at full load and that too without Heatsink for MJE13005.
    can anybody please let me know, what changes have to do conversion of PCB from through hole to SMD.

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    Re: SMPS Through Hole to SMD Package

    Quote Originally Posted by gauravkothari23 View Post
    1 Amp SMPS
    For a given output the internal current waveforms are expected to have much higher current peaks. Can all your components tolerate greater than 1A?

    Can all terminals, and all solder joints tolerate greater than 1A?

    Just 1 ohm of parasitic resistance, at 1 Ampere, generates 1 V of voltage drop and 1 Watt of heat. 1W of heat is too hot for me too hold between my fingers. If it's in a tiny wire (or copper trace, or solder fragment) then it may generate even high temperatures.



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    Re: SMPS Through Hole to SMD Package

    you may have made a mistake in converting to the SMD board - check all the wiring and circuit tracks carefully - to make sure you have copied exactly

    then check which parts are failing - besides the xtor - this will give you a clue as to whether you are trying to dissipate too much power in some smd parts and thereby killing them



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    Re: SMPS Through Hole to SMD Package

    you may have made a mistake in converting to the SMD board
    The arbitrary component placement in the schematic makes it hard to read. I would need to reorder the circuit in a functional way.

    At least one detail seems wrong, Q1 in parallel to a transformer winding.

    I guess TR1 should have two separated primary windings. Apart from obvious schematic errors, self-oscillating converters are never simple. A small modification can make it fail.



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    Re: SMPS Through Hole to SMD Package

    I have rechecked my SMD Circuit with through hole components, but nothing seems incorrect. have also checked for any shorts. but have not got any issue with my PCB design.
    have attached the new circuit with tranformer winding connections.
    do SMD zener diodes can create this problem, are watts of SMD components lower than through hole components.



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    Re: SMPS Through Hole to SMD Package

    Hi,

    but have not got any issue with my PCB design.
    Why don't you show us?

    are watts of SMD components lower than through hole components.
    It depends....
    That's why there are datasheets.
    Either you or we need to read them to find out

    Klaus
    Please donīt contact me via PM, because there is no time to respond to them. No friend requests. Thank you.



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    Re: SMPS Through Hole to SMD Package

    the watts of SMD components are usually quite a bit less than thru hole - especially peak power or pulse ratings - it is a size thing ...



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