> -----Original Message-----
> From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu]On Behalf
> Of Jinx
> Sent: 08 December 2006 01:07
> To: Microcontroller discussion list - Public.
> Subject: Re: [PIC] ADC voltage mismatch problem
> 
> 
> > There's an implied assumption that VCC is a stable voltage.
> > I've never tried (for example) VCC as a sine wave added to an
> > offset so that it was always inside the limits, but varying
> 
> If ripple is a problem, stop the Vcc boost immediately before sampling
> and there'll be no noise on Vcc. With a ** suitable ** reservoir cap
> and low enough Ivcc (SLEEP the PIC for an ADC reading ?), Vcc
> should hold up for the acquisition. I'd be quite confident though that
> noise can be filtered to an app-dependent ** acceptable ** level
> without going to a lot of software/firmware bother
btw: you aren't going to drive a boost directly off an IO pin of a device pic that is being powered by the boost so your going to need at least a buffer stage.

might be less hassle all round to look for a suitable fit and forget step up IC (i know they exist though i don't have any part numbers to hand for a 3.3V to 5V one)


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