-200 VDC regulator

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BWRX

BWRX

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jogas said:
I need to reduce a -270 VDC down to -200 at 20 mA.
Is there any three pin component available?
Click to expand...

Have you thought about just using a zener (or a string of zeners), resistor(s), and pnp transistor? A 70V drop across a transistor sinking 20mA is only 1.4W. You could also put a resistor in series with the collector to reduce the transistor's dissipation.
 
jan.didden

jan.didden

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Re: Re: -200 VDC regulator

jogas said:
Hi,

I need to reduce a -270 VDC down to -200 at 20 mA.
Is there any three pin component available?
I only found a VB408 that is a positive regulator :(

Thanks in advance for your help
Giuseppe
Click to expand...


If your raw supply is floating you can use a pos regulator. Just ground the pos terminal and use the common terminal (which normally would be grounded) as the neg terminal. Works like a charm.

Jan Didden
 
SY

SY

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Poke around National Semiconductor's site. There's a nice paper by Michael Maida on using a HV bipolar to limit the voltage across a 317-type regulator. I think the paper is Linear Brief LB-47. This paper only shows positive regulators, but by using PNP (or p-channel FET), a 337, and turning around the diodes, you can make a negative regulator.

Or you could use the positive regulator as published inserted in the ground leg of your raw supply.
 
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