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what is a MM5422N ?
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Martin.M:
I want to know please what exactly is a MM5422N ? bec. I have a bunch of them, no datashs, nothing.

thank you
tooki:
Could they be the ones mentioned in this PDF? https://media.searchelec.com//specshee/NATIONAL/NationalSemiconductorOptoelectronicsHandbook1979_text.pdf

(too big to attach)
ebastler:
It would have helped to know whether the mystery part is indeed a 22-pin DIL package.

"Digital alarm clock", and while the databook does include a block diagram, it does unfortunately not show a pinout. Hope the OP does not have too many of these on the shelf...
Martin.M:
thank you,

hard to find a application for that
I have some of them, also some 5457
is a 5422N a 5457 in another DIL package?

they are both alarm clocks, hours + minutes, no seconds.
I am searching for a application to sold a alarm clock from that, just for fun.
Importat to me is what kind of LED display is used there , what they mean  "duplex display"? At best the complete datasheet + application from NS.

f you want one of them I can send it in a envelope :-) here are 18 pcs 5422 and 18pcs 5457, a lot of alarm clocks, radio clocks..  )
retiredfeline:
Duplex probably refers to a multiplexing technique for reducing pins that I've seen in other clock chips, most recently a current Chinese part, where the half of the LEDs are powered on each half cycle of the rectified but unsmoothed AC supply. So you will need the datasheet anyway for more details.
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