Re: PIC18LF8621 and WISP628

I didn't follow the subject but I presume is about programming a 
3.3V PIC from WISP628, which looks to me without any problem if the
LVP is used. I know the LVP specification is guaranteed at +5V, but 
wisp628 have limiting resistors (as far I remember) on LVP, SD and 
SK. 

Dual supply board (+3.3V and +5V) is a good option if the LDO may be 
resistor programmed. LM317 (not a really LDO) is perfect for this.

Vasile

BTW Wouter, all PIC16LF876 used by me, works at 20MHz supplied at 
3.3V in HT mode with crystals (not resonators) on oscin/oscout pins
I presume will be minimum failures on 16LF628A too (less than 3% 
looks ok for you ?).


--- In jallist@yahoogroups.com, "Wouter van Ooijen"  
wrote:
> > Another idea I guess would be to come up with a "LF" version of 
the
> > the Wisp628 itself, such that it also ran at 3.3 volts.
> 
> Problems:
> - the max232 won't work properly from 3.3V
> - the charge pump that creates the Vpp won't work properly
> - IIRC most PICs are not spec'd to run at 20 MHz at 3.3V
> 
> > I guess another approach would be to see if I could modify the 
board
> > to run (temporarily) at 5 volts while programming.  But this 
would be
> > a pain and probably error prone.
> 
> A schottky diode from the 3.3V to the PIC Vcc?
> 
> Wouter van Ooijen
> 
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