[Novatek]

General Description
The NT91214/15 is a single-chip, silicon gate, CMOS integrated circuit with an on-chip oscillator for a 3.58MHz crystal or ceramic resonator. It provides a dialing pulse (DP) or dual tone multi-frequency (DTMF) dialing. A standard 4 x 4 matrix keyboard can be used to support either DP or DTMF modes.

FEATUREs
■ One touch redial operation
■ Tone/Pulse switchable
■ 32 digit capacity for redialing
■ Automatic mixed redialing (last number redial) of pulse to DTMF with multiple automatic access pauses
■ PABX auto-pause is 2.2 seconds
■ DTMF Timing:
    Manual dialing: minimum duration for bursts and pauses
    Redialing: calibrated timing
■ Hands-Free control function
■ Wide operating voltage range: 2V to 5.5V
■ Key-in beep tone output
■ Digits dialed manually after redialing are cascadable and stored as additional digits for the next redialing
■ Uses inexpensive ceramic resonator (3.58 MHz)
■ Two versions for different telephone systems
■ Built-in power up reset circuit
■ Four extra function keys: flash, pause, redial and DP or DTMF mixed dialing
■ 4 x 4 (or 2 x 8) keyboard can be used
■ Low standby current