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    High voltage input linear regualtor using IGBTs?

    Hi
    We are doing a high voltage linear regulator to run off rectified 240VAC.
    The following two schematics are our possible choices.
    They would more cheaply be done with the FET replaced with a IGBT. What do you think of low current linear regulators using IGBTs?

    (Output is 3V, 6mA max in each case)

    LTspice sim also attached

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    Re: High voltage input linear regualtor using IGBTs?

    Hi,

    3V, 6mA calls for a capacitive AC supply.
    Otherwise a linear supply may dissipate about 2W.

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


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    Re: High voltage input linear regualtor using IGBTs?

    Thanks yes you are right, i should have said the 6mA is only when DALI is transmitting...which isnt often, most often the current draw is around 1.4mA.



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    Re: High voltage input linear regualtor using IGBTs?

    They would more cheaply be done with the FET replaced with a IGBT.
    Why do you think so?


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    Re: High voltage input linear regualtor using IGBTs?

    It sounds as though you need only 1.4 mA most of the time? Then it may be possible to store some juice for your infrequent 6mA load in a large capacitor. Install a resistor to provide some isolation. Then it charges over a period of time by stealing just a tiny amount of current.

    My simulation has no IC's nor transistors nor mosfets.

    Mains 230VAC is dropped through 40k resistor and 160V zener diode (in series it drops 160V). You might get by with 1/2W rating since they dissipate 0.7W at less than 50 percent duty cycle.

    The 160v zener diode may need to be assembled from lesser values.

    I detached the 3.3V zener to demonstrate that usable volt and Ampere levels can be obtained, by adjusting values and watching results.

    Click image for larger version. 

Name:	230VAC dio bri dropped via 160v zener 40k resis to 3VDC load 2k switched load 500.png 
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    The 6mA load has its own large reservoir capacitor. They are isolated via 10k resistor. It takes a few minutes to charge to 3V. When you press the switch it discharges in about 1/10 second. (If you need longer On time then you can increase the reservoir capacitor to whatever size is necessary.)

    Since the 6mA section draws a tiny amount of juice from the normal load, the normal load does not drop below 2.9v.


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