Re: Adapting this NSC app note for my +150V regulator

On Mar 21, 1:38 pm, Fred Bloggs <nos...@xxxxxxxxxx> wrote:
Hi all. I have the need for a linear regulator to supply +150V at 0 to
50mA from a 260VDC unregulated input. There's this National app note,
"High Voltage Adjustable Power Supplies", with which you may be
familiar:

http://www.national.com/ms/LB/LB-47.pdf

It seems that using something like, say, TIP50 for Q1 and Q2, and
reducing R3 should do the trick. Is there anything I have overlooked,
though? Regulated power supply design is not my area of expertise.

Thanks in advance,

--Dave in New York

PS: TIP50 data*** "for those wot wanna see it":
http://www.fairchildsemi.com/ds/TI/TIP50.pdf

The TIP50 is not good enough. Taking the approach of short-circuit
limiting at 2x the maximum regulated current rating, as in LB-47,
exceeds the SOA of that particular transistor. Even strict limiting at
50mA would be too much.


Good point. I know there are some transistors intended for horizontal
output service in TV sets that are pretty beefy, with high C-E
breakdown voltage ratings. I'll look into those.
.

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