Switch Mode Power Supply -help needed

Discussion in 'The Projects Forum' started by mishra87, May 25, 2016.

  1. mishra87

    Thread Starter Member

    Jan 17, 2016
    170
    2
    For universal input -
    I want to design - 12V@ 500mA

    Lets say i want to design it by using Power Integration PWM switcher (TOP family)

    Now my doubts are -
    1. Needed only in 100ms pulse once in a hour - I do not understand this terminology could anybody explain me and what all the parameters to get this pulse.
    2. It should be able to withstand impulse surges of up to 10kV for 1 ms - what all i need to do to achieve this and which device i need to add to limit this .

    Thanks in advance !!!
     
  2. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    Do you want to make a 12vpsu from an Ac supply?
     
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  3. mishra87

    Thread Starter Member

    Jan 17, 2016
    170
    2
    yes,

    85VAC to 265VAC, 50Hz

    Hope this help...!!!
     
  4. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,998
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    You're biggest problem is getting the pcb and pulse transformer made to your design, you can buy ready made psus far cheaper than making them, have a look at different chip technologies like Uc3845 series, or TL494, Tea1733/5 series.
     
    Last edited: May 25, 2016
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  5. mishra87

    Thread Starter Member

    Jan 17, 2016
    170
    2
    Please

    Please reply on the basis of my doubt mentioned in post 1.
    The PCB and part selections are not a issue for me !!!
     
  6. mishra87

    Thread Starter Member

    Jan 17, 2016
    170
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    Still recommendations awaited on this particular. ..!!!
     
  7. AnalogKid

    Distinguished Member

    Aug 1, 2013
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    Your question is not very clear. First, if you want to use a PI part to make a 12 V low power supply, they have tons of application notes and reference designs. Also, places like Pioneer Magnetics make the transformers for basic designs, so you don't have to design and build the magnetics. But it will be much cheaper to just buy a 12 V wall wart on ebay.

    After that, is you question about making a 12 V pulse once each hour? If so, what is the output current the pulse has to supply?

    The best way to make a short pulse after a long delay is with a counter. This can be in a little 8-pin PIC or a couple of CMOS logic parts.

    ak
     
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  8. mishra87

    Thread Starter Member

    Jan 17, 2016
    170
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    Thank you so much for your reply !!!

    It does not matter which PWM switch one can choose. My intention is only to discuss below point means how it can be achievable for above specifications .
    1. Needed only in 100ms pulse once in a hour
    2. should be able to withstand impulse surges of up to 10kV for 1 ms .

    Could you suggest any part related to that so that i can have a look .

    Hope this help in further discussion .
     
    Last edited: May 26, 2016
  9. AnalogKid

    Distinguished Member

    Aug 1, 2013
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    It did not. For the 100 ms pulse, what is the output current?

    ak
     
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  10. mishra87

    Thread Starter Member

    Jan 17, 2016
    170
    2

    Thank you so much....

    Please consider me as a novice if I have been missing somewhere else. ..!!!

    As I mentioned in post 1.
    12V@500mA

    Now how to achieve above two conditions stated above...
     
  11. AnalogKid

    Distinguished Member

    Aug 1, 2013
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    A CD4060 is an oscillator circuit and 14 stage divider. Starting with an output period of one hour, you can calculate the resistor and capacitor needed for the oscillator using the equation in the data sheet. Once you have that, the output state is a PNP power darlington transistor and one capacitor.

    1. How accurate does the 100 ms pulse width have to be?

    2. How quickly does the output pulse have to turn off?

    2. What is the output pulse driving?

    ak
     
  12. mishra87

    Thread Starter Member

    Jan 17, 2016
    170
    2
    Thank so much for enlightening me...!
    I will work out on CD4060.

    Now let's come to point number two.

    What all need to put as a protection device so that it can withstand impulses surges of up to 10KV for 1ms.

    I have been using MOV in my previous design for surge protection like 14D751K, Bourns make between L&N, L&E, N&E. Which clamps voltage 1240V.

    What should be the basic criteria to surge protection.

    We need to take a consideration of compact size and low cost device..
     
  13. kubeek

    AAC Fanatic!

    Sep 20, 2005
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    Where is that 10kV pulse happening? On the input line i.e. line to neutral, on the output line i.e. +12V to 0V, or between primary and secondary?
    What nature is that pulse? You need to know the impedance of the impulse source, or at least how much energy you need to withstand. Where is this pulse coming from?
     
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  14. mishra87

    Thread Starter Member

    Jan 17, 2016
    170
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    Heartiest thanks for your reply. ..

    Let's say its all about SMPS design.
    If impulse surge of 10KV for 1ms coming from lightening or some other sources then it would affect input source or output load.

    I do not understand this behavior and what does it means.
    If such so how to protect our intrument. ..!!!
     
  15. kubeek

    AAC Fanatic!

    Sep 20, 2005
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    With european norms we usually test things to 1 or 2kV between the line and neutral, through a 2uF capacitor and 40 ohm resistor if I remember correctly. 10kV seems excessive to me, but it could be you have worse storms than we have here. Best look up your local standards for EMC compatibility, european is IEC 61000-4-5.
     
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  16. mishra87

    Thread Starter Member

    Jan 17, 2016
    170
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    Thank you so much.

    I will have a look of EMC standards.
     
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