From: no@email.ads (Christopher E.Giese) >Here is one charge pump circuit. It works best if the square-wave >oscillator has a low output impedance, and if Schottky diodes are >used: > VCC > O > | > _|_ > \ / > __V__) > | | + ( | / > VCC | | | |\ | > O .----+ +------+---| >|------+---------> 2 * VCC > | | | | |/ | | > | | | | + / + | + > ______|_____ | ___|___ >| | | _______ >| square- | | | >| wave +---+ ___|___ >| oscillator | | _____ >| | | ___ >|____________| | + | | / . > | | | | | /| > | '---+ +-----+------|< |------+---------> -2 * VCC > | | | | | \| | > ___|___ + | | | / | > _____ _|_ ___|___ > ___ \ / _______ > . __V__) + | + > ( | ___|___ > | _____ > ___|___ ___ > _____ . > ___ > . >(I love ASCII art!) More capacitor-diode stages can be added to get >higher output voltages. I don't know how efficient it is. >Hope this helps. Actually, I think the -2 * VCC is -1 * VCC, unless the oscillator output swings below ground. Bill
Date: 23 Aug 1996 19:03:22 -0400
Original Subject: Re: Help my rusty math please