Hi.

One of the five lines I need to convert is a data clock, but it's about 1kHz,
so hopefully, this won't be a problem.

I'll check out the hex buffers though, thanks for the suggestion

Regards,
Mark

> -----Original Message-----
> From: piclist-bounces@mit.edu 
> [mailto:piclist-bounces@mit.edu]On Behalf
> Of Jake Anderson
> Sent: 03 December 2004 13:07
> To: Microcontroller discussion list - Public.
> Subject: RE: [EE]Darlingon array, was Will this voltage 
> shifter work for
> m y application?
> 
> 
> just a caution and a suggestion to boot
> if you are trying to send high speed data you will want a 
> fairly "strong"
> pull up depending on signal length.
> 
> capacitive and inductive effects mean that it may take the 
> line a while to
> rise from a low to a high.
> I had a similar problem with a level converter.
> I was running from 3.3v to 5V SPI, over about 20cm of cord 
> (the cord had the
> 5v signal on it), I just used a TTL hex buffer.
> its high threshold was around 2 and a bit volts and the 
> dataflash had a
> minimum output of 3
> 
> other upside is 6 converters in one chip ;->
> 
> I was running that at ~62KHZ I think
> 20mhz 16F877 at fosc/64 SPI
> resistor divider down converter and the buffer back up.
> 
> 
> > -----Original Message-----
> > From: piclist-bounces@mit.edu 
> [mailto:piclist-bounces@mit.edu]On Behalf
> > Of Russell McMahon
> > Sent: Friday, December 03, 2004 23:06
> > To: Microcontroller discussion list - Public.
> > Subject: Re: [EE]Darlingon array, was Will this voltage 
> shifter work for
> > m y application?
> >
> >
> > > Thinking about the OpAmp solution, wouldn't a comparator be even
> > > better/more
> > > suited to my application?
> > > LM339 quad would do the trick, (or rather a pair of them 
> - I need 5
> > > comparators - bugger!)
> > >
> > > I assume the LM339 can switch at 1kHz comfortably?
> >
> > LM339 is a technically superior solution BUT, unlike the L:M324
> > which drives
> > high actively, all its comparators are "open collector" 
> output so need a
> > pullup resistor. using Dave Minklers suggestion of using pullups
> > on the PIC
> > you could do it with no external pullups.
> >
> > > You mention a decoupling capacitor on the supply.  I am using
> > an LM317LZ
> > > vreg
> > > to provide regulated 5v, from a 12v DC input (& another for
> > 1.5v) for PIC
> > > and
> > > possibly now the LM339, which has a 0.1uF(IIRC) capacitor 
> on the output
> > > already - so will I still need a further decoupling capacitor
> > for the IC?
> >
> > A 0.1 uF for each IC between its power supply pins is usually a
> > good idea.
> > Not always essential - but it's a shame to have things fail due
> > to excessive
> > noise for want of a cap worth a few cents.
> >
> >
> >         RM
> >
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> > View/change your membership options at
> > http://mailman.mit.edu/mailman/listinfo/piclist
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