Problem is the ICs like that are dumb and often don't have features that you might need. NTE has some DTMF ICs, but I have no idea on the specifics. That would accomplish your application right there if you could find such a chip still. There used to be ICs with DTMF tone generation capability, a keypad interface to scan a 4x4 keypad and dial the numbers, and, better yet, they had memory dial capabilities so you could preprogram a given multi digit number in to a memory location and dial it with a button press. If the SLICs with DTMF that SiLabs has are DTMF encoders and the SLIC function is CPE side and not CO line card side, you may have a solution with those.
Looks like Silicon Labs, Ixys, maybe ST might have something, I don't know, but the supply picture didn't look good and it's not clear they'd even do what you need. A quick non exhaustive search of Digikey and Mouser shows me that few if any of the classic old DTMF dialer ICs are still made, and no likely devices in the category of DTMF Dialer IC are even stocked by those major distributors. There were some from National, Mitel, Teltone, many more, but a lot of those chips have gone obsolete. So the thing is there are a bunch of DTMF generator ICs, I used to use ones like the TCP5088, TCP5089. I don't recall what series chip they use, but I'm pretty sure it'd be one of the original low end series that is less than $3 in single quantity at DigiKey. Trivial to do with a single MCU if you can program MCUs.įor instance the MSP430 has a DTMF generation application note and sample code that shows you how to generate DTMF with them.
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