On 04/03/11 19:36, Dwayne Reid wrote:
> That's the software side.  The hardware side is also a little
> challenging: the SPI buss and those shift registers are running from
> 5Vdc.  Most modern CPLD's seem to be 3.3V or lower.
>
> So: I'm looking for suggestions for a small to medium size CPLD that
> runs at 5V and has at least 40 macrocells.

The Xilinx XC9500 series was still in production last time I checked,=20
but very expensive.

You'd be better off getting a couple of 74LVC or 74LVX chips to use as=20
bus translators, and use an XC9500XL series chip (3.3V). Far cheaper,=20
and far easier to obtain parts...

Heck, the I/O pads are 5V tolerant -- if your hardware doesn't mind=20
being driven from 0V/3.3V TTL, you can do away with the buffers and wire=20
the CPLD straight in.

Only thing you'd need to add is a low-current 3.3V power supply. An LDO=20
would be the ideal, something like an LP5951MF-3.3 (NatSemi) or ZXCL330=20
(Zetex / Diodes Inc). One chip (30p ish) and two cheap ceramic=20
capacitors is all you need.

--=20
Phil.
piclist@philpem.me.uk
http://www.philpem.me.uk/
--=20
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