The BU8874 and BU8874F are DTMF receiver ICs developed for use in telephone answering machines, and convert 16 different types of DTMF signals into 4-bit binary serial data. In addition to a compact 8-pin DIP (BU8874) package,these receivers feature 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 microcontroller.

Features
1) Dynamic range of 45dB. (internal AGC)
2) Power down mode.
3) 4-bit binary serial data output.
4) Guard time can be controlled through host microcontroller.
5) Input pins equipped with hysteresis. (ACK pin)
6) 4.19MHz crystal resonator can be used.
7) 8-pin DIP package. (BU8874)

Applications
Telephone answering machines