91215 DTMF

The UM91214/15 is a single-chip,sillcon gate,cmos integrated circuit with an on-chip oscillator for a 3.58 MHz crystal or ceramic resonator.It provides dialing pulse (DP) or dual tone multi-frequency (DTMF) dialing.A standard 4x4 matrix keyboard can be used to support either DP or DTMF modes.up to 32 digits can be saved in the on-chip RAM for redialing.In the DTMF mode, minimum tone duration and minimum intertone pause provide for rapid dialing.maxmum tone duration is dependent upon the key depression time in manual dialing.