PCD3312C

The PCD3311C and PCD3312C are single-chip silicon gate CMOS integrated circuits. They are intended principally for use in telephone sets to provide the dual-tone multi-frequency (DTMF) combinations required for tone dialling systems. The various audio output frequencies are generated from an on-chip 3.58 MHz quartz crystal-controlled oscillator. A separate crystal is used, and a separate microcontroller is required to control the devices.

Both the devices can interface to I2C-bus compatible microcontrollers for serial input. The PCD3311C can also interface directly to all standard microcontrollers, accepting a binary coded parallel input.

With their on-chip voltage reference the PCD3311C and PCD3312C provide constant output amplitudes which are independent of the operating supply voltage and ambient temperature.

An on-chip filtering system assures a very low total harmonic distortion in accordance with CEPT recommendations.

In addition to the standard DTMF frequencies the devices can also provide:
· Twelve standard frequencies used in simplex modem applications for data rates from 300 to 1200 bits per second
· Two octaves of musical scales in steps of semitones.