>>I'd like to convert the output of a 12V 4000 Series CMOS IC to the
>>digital input of my PIC16C76 which is running at 5V.

> There are several answers...
>A 47K series resistor will work, as the PIC input diodes will clamp it.
However there can be issues
with relying on the input diodes (discussed at length in the past).
You could use a simple resistive divider - 33K and 22K would be about right
(4.8V out at 12V in).
>

And a few more than that as well ;-)

Here's just a few of them:

- The CD40109 can level shift in either direction.
4 to a package
Less tricky to use than most
TI - incl free samples
    http://focus.ti.com/docs/prod/folders/print/cd40109b.html
other
        http://www.radanpro.com/rdownload/cd/cd_40109.pdf

About $US0.80 each in 1's from Digikey

- a ULN280x (see below for X)  will do 8 inputs per 18 pin package. This
inverts, which will probably not be a problem. It also has open collector
outputs - which will also not be a problem if you use inputs with internal
pull-ups enabled (or external pull-ups). (ULN200X does 6 per package).

This is the ULN200x 6 input series. I think the 280X series is similar but
do check.

ULN2004    6 to 15v in
ULN2002    nominally 14 to 25v in but will work from about 10v up on light
loads
ULN2003    smell of an oily (2v) rag
ULN2004    smell of several oily rags
ULN2001    No input resistor - add your own

- There are a few zillion other ways as well.

eg opto couplers, FET's, discrete transistors, ....



        RM

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