What do you mean by a "voltage doubler"? Is this something that would work off of the 3.3 v supply and able to produce 25 mA? Regards, Gordon Williams ----- Original Message ----- From: "Jinx" To: "Microcontroller discussion list - Public." Sent: Thursday, December 07, 2006 4:01 PM Subject: Re: [PIC] ADC voltage mismatch problem > > > 1) The sensor output (up to 5V) is greater than the allowable ADC > > input because the PIC is at 3.3V. A voltage divider would have to > > use large resistances ~50 - 100 Kohm to limit the current from the > > sensor (max 0.1mA). This exceeds the PIC ADC input impedance > > People have reported satisfactory results with a longer sampling time > > Another option may be to boost the PIC's Vcc to 5V with a pin- > driven voltage doubler for the duration of the sampling. I'm pretty > sure I've seen that suggested in a Microchip Tricks 'n' Tips or AN > > There's the obvious op-amp buffering/amplification of course > > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist