L3916A Datasheet | STMicroelectronics

® SPEECH AND 14 MEMORY DIALER WITH LED DRIVER SPEECH CIRCUIT 2 TO 4 WIRES CONVERSION PRESENT THE PROPER DC PATH FOR THE LINE CURRENT AND THE FLEXIBILITY TO ADJUST IT AND ALLOW PARALLEL PHONE OPERATION PROVIDES SUPPLY WITH LIMITED CURRENT FOR EXTERNAL CIRCUITRY SYMMETRICAL HIGH IMPEDANCE MICROPHONE INPUTS SUITABLE FOR DYNAMIC ELECTRET OR PIEZOELECTRIC TRANSDUCER ASYMMETRICAL EARPHONE OUTPUT SUITABLE FOR DYNAMIC TRANSDUCER LINE LOSS PENSATION INTERNAL MUTING TO DISABLE SPEECH DURING DIALING LIGHTED DIAL LED CONSUMING 25% OF LINE CURRENT DIALER CIRCUIT 32 DIGITS FOR LAST NUMBER REDIAL BUFFER 18 DIGITS FOR 13 MEMORY REDIAL ALLOW MIXED MODE DIALING IN EITHER TONE OR PULSE MODE PACIFIER TONE PROVIDES AUDIBLE INDICATION OF VALID KEY PRESSED IN A BUZZER OR/AND IN THE EARPHONE TIMED PABX PAUSE FLASH INITIATES TIMED BREAK: 585ms. CONTINUOUS TONE FOR EACH DIGIT UNTIL KEY RELEASE USES INEXPENSIVE 3.579545MHz CERAMIC RESONATOR POWERED FROM TELEPHONE LINE, LOW OPERATING VOLTAGE FOR LONG LOOP APPLICATION SO28 ORDERING NUMBER: L3916AD PIN CONNECTION (Top view) KEYPAD CONFIGURATION DESCRIPTION The device consists of the speech and the dialer. It provides the DC line interface circuit that terminates the telephone line, analog amplifier for speech transmission and necessary signals for either DTMF or loop disconnect (pulse) dialing. Note: PAUSE/LND: PAUSE and LND functions are sharing the same key with different sequence. Hereafter, PAUSE and LND keys are referring to the same key. March 2000 1/14 BLOCK DIAGRAM DESCRIPTION (continued) When mated with a tone ringer, a plete telephone can be produced with just two ICs. The DC line interface circuit develops its own line voltage across the device and it is adjustable by external resistor to suit different country’s specification. The speech network provides the two to four wires interface, electronic switching between dialing and speech and automatic gain control on transmit and receive. The dialing...