Analog switch for 2x charge pump?

Sep 22, 2006 3 Replies
J

Hi,



I need to double my input voltage of 5V to get ~10V, < 50 mA current draw. Seems like as switched-capacitor charge pump is the easiest route.



I'm thinking of using PWM outputs from my uC to drive an analog mux to create the charge pump, but I see most analog switches/mux'es are limited to +/- 6V inputs.



Any suggestions on an inexpensive approach to implementing the charge- pump?



Regards, John.



P.S.



Joerg, if you're reading this, thanks for answering my questions on the crystal oscillator, I went to thank you but my ISP didn't carry the article any more.


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L

You also have to supply VCC above the inputs/outputs.

What's wrong with mosfets?

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M

or diodes...

if you have a 5Vp-p square wave you can get ~10VDC just using caps and diodes...

Mark

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P

What's wrong with using a switched cap 2x boost coverter from National / TI etc.? They cost way less than $1 (plus the cost of the caps, which you'll need anyway). Take a look at the 266x series from National for an example.

If you want to make your own, you could do it with caps and FETs (as synchronous diodes), but it would probably be easier using a part designed for the job :)

Cheers

PeteS

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