DTMF receiver for telephones

The BU8871F is a DTMF receiver ICs developed for use in telephone answering machines, and converts 16 different types of DTMF signals into 4-bit binary serial data. It features a wide dynamic range, eliminating the need for an external input amplifier. Expertise from a number of companies has been incorporated into these products to enable guard time control through a host microcomputer.

Features
1) Dynamic range of 45dB. (internal AGC)
2) 4-bit binary serial data output.
3) Guard time can be controlled through host microcontroller.
4) Input pins equipped with hysteresis. (ACK pin)
5) 4.19MHz crystal resonator can be used.

Applications
   Telephone answering machines