From: "Frank Bemelman"
Subject: Re: Simple adjustable 0 - 400V regulator, with flaw
Date: Sat, 18 Jan 2003 17:03:11 +0100
X-Newsreader: Microsoft Outlook Express 6.00.2800.1106
Organization: EuroNet Internet
NNTP-Posting-Date: 18 Jan 2003 16:03:17 GMT
"Winfield Hill" schreef in bericht
> The Intersil HIP5600 is an adjustable three-terminal regulator
> that can be thought of as a 500V version of the LM317. I've
> used it in many of my lab instrument designs and found it to
> be reliable and, like the LM317, an elegant design simplifier.
> For example, here's a simple adjustable 0 to 400V regulator,
> with a fixed-voltage feature.
> . +480V ___ HIP5600
> . ---| |---+---+-----------(O) HV out
> . |___| | |
> . | | 1.5k
> . | | | adjust, 0 - 400V
> . '---- | --+----o->o--------,
> . | o--, |
> . 10uF === 300V | 500k
> . 450V | fixed | pot
> . | 380k |
> . ______|______________|_____|____
> . gnd
> The switch allows one to select a fixed 300V output, or to
> adjust the voltage to any value between 1.2 and 400 volts.
> But this circuit has one potential problem that can cause
> a component failure. As a design quiz, tell us what the
> problem is, and find a solution that doesn't significantly
> affect any of the circuit's functionality. Hint, the '5600
> isn't the vulnerable part.
While changing the switch, the output goes +480V for
a very short moment. The capacitor may not like that.
A higher rated cap is the easy way out, or place a
cap from the resistor to ground, so the short moment
the switch is filtered out.
(remove 'x' & .invalid when sending email)