Touchtone chips?

justme schrieb:

"touchtone" probably still is a Bell / AT&T trademark. Try "DTMF" at lets say: ebay.com Business&Industrial The old 8870 decoder / receiver is still popular. The encoder/decoder / tranceiver would be 8880 but is rarely used now. If you have a microcontroller use software & a D/A for sending DTMF.

MfG JRD

Thanks, Rafael.

I don't want to use software.

Why do you say that the 8880 is rarely used now? Is there a better one?

Joe

Then you have to use two ICs. The MK5089 transmitter is still available at ebay.com Originally Mostek but many second-source manufacturers.

The 8870 is the most common receiver. Note that the old 8870 was in SC-filter technology. There a new cheaper "8870" from lets say Holtek that are digital and not fully compatible: they need external caps for the crystal and the integrated op-amp is less stable if you try to drive additional inputs with it.

Not really. The simple answer is that transeivers weren´t even popular in the 80ies.

The Mitel 8880 may have had a second-source some time. But it is supposed to be be used with a parallel interface by a microprocessor. The software-protocol was somewhat weird, the hardware of the chip is ok. Mitel changed to Zarlink and there they still have: MT8880C Integrated DTMF Transceiver with Motorola Compatible Processor Interface MT8885 Integrated DTMF Transceiver with Power-Down and Adaptive Micro Interface MT8888C Integrated DTMF Transceiver with Intel Micro Interface MT8889C Integrated DTMF Transceiver with Adaptive Micro Interface MT88L85 3 V Integrated DTMF Transceiver with Power-Down and Adaptive Micro Interface MT88L89 3 V Integrated DTMF Transceiver with Adaptive Micro Interface

The Silicon Systems SSI 75T2089 was a Mostek-type transmitter and a SSI 202 receiver in a DIL22 and always less popular. The 75T2090 the same with call progress detection, the 75T2091 in DIL28 and PLCC had another call progress detection. These were about 1990 in the databook. SSI changed to TDK then to Teridian and by that time the tone-signalling products had gone.

MfG JRD

Yes, thank you, Rafael.

I have used the SSI 202 and the 75t2090. I like/d them. I was just wondering if there were any later and better chips than these.

Why do you say that dtmf has gone. The world runs on them.

Joe

The old 80ies ICs were based on SC-filters, not very shrinkable, these fabs are gone now. So the manufacturers like SSI/TDK are unable to keep them in production unchanged. I do think TDK did try to convert some of their more profitable old ICs like the low-speed modems to digital.

Analog DTMF may be still around, digital ISDN here in Europe is biting the dust now: to complex to be viable.

But microcontrollers have come a long way: for a DTMF-transmitter a D/A- or even a PWM-output will do. DTMF-receivers in software are not yet viable on low end

MfG JRD

Do you have a part number for these ??

hamilton

I, too, would like the part numbers.

The 75t2090 worked beautifully.

Joe

Hmmm, I thought we were talking about "ICs like the low-speed modems" from TDK !

Did I miss something or did you !!

hamilton

I did. I missed the change in topic from DTMF to modem.

Sorry.

John