On Fri, 10 Oct 2008 13:28:46 +1100, Franc Zabkar
put finger to keyboard and composed:

On Thu, 09 Oct 2008 19:37:48 -0500, Richard J Kinch
put finger to keyboard and composed:

I'm trying to identify an SMD on a PC board with some SPST keypad switches.
It has 4 terminals and is marked M1I. Each is labeled DA1, DA2, etc. on
the silkscreen, and two of the four terminals are marked A and K. All four
terminals connect off in different destinations. I'm guessing this is some
sort of debouncer or logic-level-shifter? But I'd like to know, if anyone
has any suggestions.

Diode array? (A)node/(K)athode?

Maybe the DAx parts are wired as follows:

IN1 ----+----- to uP
|
o
|
+Vcc |--||--+--||--| Gnd
o---| |---o
K |--||--+--||--| A
|
o
|
IN2 ----+----- to uP


This kind of setup is often used for ESD/latchup protection.

- Franc Zabkar
--
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