From: Winfield Hill
Subject: Re: Simple adjustable 0 - 400V regulator, with flaw
Date: 18 Jan 2003 09:05:04 -0800
Organization: Rowland Institute
References: <firstname.lastname@example.org> <email@example.com>
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>> Winfield Hill wrote...
>>> 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 |
>>> 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.
> Or 2x200V zener diodes in case the pot fails.
Actually the real circuit has that, but no, keep trying.