I looked at Fairchild’s site, and it’s no longer manufactured.
What is considered the new replacement for it, if one is available? I know there are several software solutions out there that use the Arduino to help with matrix decoding, but I’d like to know if a dedicated chip is available to do the same thing.
digikey and mouser carry it. your’e not going to like the price though - Digikey lists it for $9.66 in a DIP a package but none in stock. Mouser has the NTE one in stock for $19.00.
Why do you want to use this chip? A $3.00 micro can be programmed to do the same thing. Just because something is dedicated to a single task doesn’t mean it’s better or cost effective.
Thanks for the info. I agree, those are pricey. 
I figure on using a decoder chip to pass decoded keypad strokes back to the processor, using RS232 (found [this on Jameco, a little cheaper). Certainly a processor could handle it, but then I’d be giving up extra input lines and it seems like over kill to me. On the flip side, I chew up more PCB space and put up with added complexity on PCB design.
call it 6 of one, 1/2 dozen of the other.](https://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?storeId=10001&langId=-1&catalogId=10001&productId=171969)
That chip from Jameco IS a processor…says right on the last page of the datasheet. It’s a PIC16C54!
You could easily get something newer, say a PIC16F88 (literally hundreds of options out there, but the 'F88 came to mind first), free up a couple more pins for more options because it’s got a fairly tight internal oscillator, uses WAYYYY less power than a 16C54, and it’s a flash chip vs. eprom…and so on and so on…if you can write the code for it that is.
and to make it even easier to program, there are arduinos that are pretty cheap and there’s lots sw including libraries as well as whole sketches for keypad scanning. In fact, you could drop an arduino bootloader on a bare ATMega chip ($3) and load a sketch. bobsyerunkle!
skimask:
That chip from Jameco IS a processor…says right on the last page of the datasheet. It’s a PIC16C54!
Hell’s Bells! You are correct…I guess I’m sold then: I’ll go after a more versatile implementation by using what you suggested.
THanks!
I’m torn between using a dedicated chip and programming a microcontroller. The advantage of the dedicated chip is that you don’t have to deal with software, no uploading firmaware over and over for debugging, it just works-but it is probably more expensive.
I have found a few more:
http://www.national.com/opf/LM/LM8322.html#Overview
(Not recommended for new design)
and
http://www.mouser.com/Semiconductors/In … 18&FS=True
lo and behold, a new product, in stock, and not discontinued!!!
price for one is $3.55.
Question is, how do I get this thing on my prototyping board?
Try a priority encoder 74HCT148. Can handle 10 inputs and if two keys are pressed gives highest in chain.