DESCRIPTION
The MK53761 is a Silicon Gate CMOS IC that provides necessary signals for either DTMF or loop disconnect (pulse) dialing. The MK53761 buffersup to 18 digits into memory that can be later redialed with a single key input. Up to nine repertory numbers may bestored. Users can store all 12 signaling keys and access several unique functions with single key entries. These functions include : Last Number Dialed (LND), Softswitch, and Flash. Figure 2 shows the keypad configuration.

■ SINGLE CHIP DTMF AND PULSE DIALER
■ SOFTSWITCH CHANGES SIGNALING MODE FROM PULSE TO TONE
■ NINE NUMBER REPERTORY PLUS RECALL OF LAST NUMBER DIALED (18 digits each)
■ FLASH KEY INPUT INITIATES TIMED HOOK FLASH
■ 8 TONE PER SECOND DIALING IN TONE MODE AND 10 PPS IN PULSE MODE
■ DTMF ACTIVE UNTIL KEY RELEASE
■ MINIMUM DTMF DURATION/SEPARATION GUARANTEED (74/54 ms)
■ PACIFIER TONE PROVIDES AUDIBLE INDICATION OF VALID KEY INPUT FOR NONDTMF KEY ENTRIES
■ POWERED FROM TELEPHONE LINE, LOW OPERATING VOLTAGEFOR LONG LOOP APPLICATIONS