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    Closed: Re: Filter Cutoff Frequency

    Presumably also, if its an input stage to an isolated SMPS, and the oputput of the SMPS is earthed, then that also bypasses the input filter common chokes/capacitors.

    - - - Updated - - -

    You...
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    Closed: Re: How to calculate transformer winding losses

    Yes, your transformer appears to be an planar transformer, and appears to have leakage inductance designed into it deliberately so its an “Integrated transformer” .
    Deliberate design-in of leakage...
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    Closed: Re: SMPS power stage bode plot

    Thanks, I previously thought that "Modulator gain" = [Rload/Rsense * gain factor]

    And that the complete open loop comprises the "modulator", the "power stage", and the "error amplifier".

    If...
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    Closed: Re: SMPS power stage bode plot

    I believe that the power stage transfer function can be greater than 0dB for the case of voltage mode (not current mode) , and when at the resonant frequency of the LC of the power stage....(eg buck...
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    Closed: Re: Buck converter vs buck-boost converter

    Theres also a two switch buckboost, which also has two diodes, which can serve if vout > or < vin.
    I wont draw it, i am sure you can get it.
    It has a ground referenced output.......ie the same...
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    Closed: Re: Buck converter vs buck-boost converter

    Try the LT8705...this is a "bock or boost" converter........it acts as a buck if vin>vout, and acts as a boost of vout > vin

    LT8705...
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    Closed: Re: Any ideas about this 400V, 1A Bench PSU?

    I replaced the shorted LLC converter FETs in the 400V PSU...and the IR21531S, but when i re-assembled and switched on it went bang again and wouldnt work.
    Once again, the FETs blew up and were again...
  8. Closed: Vias covered in solder resist get outgassing problems?

    Hi
    We have a load of 0.3mm vias on our 4 layer PCB. Surely it will be OK if I coat them in solder resist? We wont get “outgassing”?
    (Outgassing is where covered over vias explode in the PCB...
  9. Closed: Re: Battery cutoff voltage vs 0% battery voltage

    if its a lithium battery then it may well have a circuit in it which stops you from being able to discharge it further down than 3v.
    If not then you should put one such circuit in there.
    But yes,...
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    Closed: Re: Buck converter vs buck-boost converter

    In Buck-Boost you will tend to get more switching losses as your fet off state voltage will gernerally be higher.
    Also, the rms fet current will be higher with a buck-boost.
  11. Closed: Re: Which transformers can pass approvals testing rergarding isolation voltage testin

    5 and 6 are primary bias.
    I am not sure if their were scorch marks, they just told us we failed.
    If it goes over 3mA when 3.5kv is applied for one minute then its a fail.....

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    Closed: Any ideas about this 400V, 1A Bench PSU?

    Hello,
    Does anyone have a schematic for this HSPY-400-01 Bench power supply? (400V, 1A)
    ...
  13. Closed: Re: Which transformers can pass approvals testing rergarding isolation voltage testin

    Thanks, the pinout is as attached. There was tubing used yes.
    As you know, There is easily 8mm betweeen primary pins and secondary pins.


    Thanks, as you know, there is no need for slotting as...
  14. Closed: Re: Which transformers can pass approvals testing rergarding isolation voltage testin

    Thanks, its re-inforced insulation.
  15. Closed: Re: Which transformers can pass approvals testing rergarding isolation voltage testin

    Yes, and as discussed, its primary, bias and secondary with TIW.
    The primary bias coil is the last to be wound on it, (so its the top layer)


    The creepage or clearance from secondary termination...
  16. Closed: Re: Which transformers can pass approvals testing rergarding isolation voltage testin

    TEX-ELZ Triple insulated wire by Furukawa is surely rated to 3.5kv for one minute?

    https://www.furukawa.co.jp/tex-e/en/product/texe_feature.html
    There is easily >8mm of spacing between primary...
  17. Closed: Which transformers can pass approvals testing rergarding isolation voltage testing?

    Hello,
    Our contractor designed a 10W, 24Vout, offline Flyback SMPS for 240VAC input. He had a split primary and a bias coil on the primary side, both wound with enamelled copper wire. He also had a...
  18. Closed: Protecting the inputs of HV7802 current monitor from damage due to inrush current

    Page 4 of the HV7802 datasheet (RHS of page, 2nd paragraph down), states that adding a resistor into the LOAD pin gives protection for the HV7802.
    It states that there is a bias current at the...
  19. Closed: Re: Film capacitor failed in flyback smps at high temperature?

    Thanks, i wonder how high the temp has to be, and for how long, with the cap of the top post to get this failure?
    Its datasheet doesnt tell of this.
  20. Closed: Film capacitor failed in flyback smps at high temperature?

    Hello,
    We are using the ECW-FD2J185 (1.8uf, 630v) film capacitor in our offline flyback smps, 240vac input.
    It is for 24v, 10w output.

    We sent it off for extreme temperature testing and it...
  21. Closed: Re: Input stage to 24W buckboost LED driver is high in component count.

    Thanks, yes if we cant find low enough rdson fets (which we probably wont at the high vds) then we will use a standard diode.....
  22. Closed: Input stage to 24W buckboost LED driver is high in component count.

    Hi ,
    The attached is an LTspice sim and pdf schem of the input stage to a 8-136vdc input , 24w buckboost led driver.
    The Vin may also go up to 385VDC for one second. (I presume this is some kind...
  23. Closed: Re: Supply 5V, 5mA from the 240VAC mains without SMPS

    Thanks asdf44, your RHS example above is absolutely great. It looks so good that id like to simulate it to see it going.,...but ltspice doent do dep mode fets.
    Though one point is that depletion...
  24. Closed: Reverse polarity protection with FET is somewhat blighted by CDG capacitance

    Hi,
    It is necessary to provide reverse polarity protection for a 24W Buckboost LED driver with Vin = 8 to 136VDC. (when vin <18v, then power can be reduced to 2W).
    I find that the diode D3 is...
  25. Closed: Why should a solder joint be less than 110degc?

    https://www.vishay.com/docs/28870/pulseloadsmdlimit.pdf
    Page 1 of the above says a solder joint should not be 110deg C or more..why?
    I looked on google etc but nothing....110degc is well below...
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