Hi Harold-
I have mentioned this before, but no one has commented.
Phillips recommends using mosfets as level shifts for I2C.  The cicuit
is below:
          +3V     +3V      +5v
           |       |        |
           |      ---       |
           R   ---------    R
           |    |  ^  |     |
           |    |  |  |     |
  3V line -+----+--+  +-----+--- 5V line
               |     |
               +-->|-+

(use fixed width font)
this presupposes that the two sides are pulled high.  There are three cases:
1/ when both sides are high, mosfet is off
2/ when 3v is pulled low, the mosfet is on, and pulls 5v side low.
3/ when 5v is pulled low, the body diode conducts and pulls the 3v side
low.

Obviously the mosfets can be really small.
David




Harold Hallikainen wrote:

>Anyone have any favorite 3V to 5V level translators? I've designed the
>MAX3008EEUP into a circuit and would like to test it before the chips show
>up in 25 weeks. I'm converting 3 lines from 5V down to 3V and 1 from 3V to
>5V.
>
>THANKS!
>
>Harold
>
>
>--
>FCC Rules Online at http://www.hallikainen.com
>
>--
>http://www.piclist.com#nomail Going offline? Don't AutoReply us!
>email listserv@mitvma.mit.edu with SET PICList DIGEST in the body
>
>
>

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email listserv@mitvma.mit.edu with SET PICList DIGEST in the body