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ST3938A Datasheet Speech - Tone/pulse Dialer - Led Indicator

Manufacturer: STMicroelectronics

Overview: ST3917A ST3917B SPEECH - TONE/PULSE DIALER - LED INDICATOR SPEECH CIRCUIT 2 TO 4 WIRES CONVERSION PRESENT THE PROPER DC PATH FOR THE LINE www.DataSheet4U.com CURRENT AND THE FLEXIBILITY TO ADJUST IT ANDALLOWPARALLEL PHONE OPERATION SYMMETRICAL HIGH IMPEDANCE MICROPHONE INPUTS SUITABLE FOR DYNAMIC, ELECTRET OR PIEZOELECTRIC TRANSDUCER ASYMMETRICAL EARPHONE OUTPUT SUITABLE FOR DYNAMIC TRANSDUCER LINE LOSS COMPENSATION FIXED INTERNALLY BY A.G.C. INTERNAL MUTING TO DISABLE SPEECH DURING DIALING AND EXTERNAL MUTING TO DISABLE TRANSMIT AMPLIFIER DURING CONVERSATION MODE LED INDICATOR EITHER FOR KEYBOARD ILLUMINATION (OR ON-LINE INDICATION) DURING DIALING AND CONVERSATION OR FOR TONE MODE INDICATION, THROUGH MU/MFI PIN . . . . . . . . . . . . . . . . . DIALER CIRCUIT STORE UP TO 32 DIGITS FOR LAST NUMBER REDIAL BUFFER, LNR IS INHIBITED IF THERE ARE MORE THAN 32 DIGITS STORED ALLOWMIXED MODE DIALING IN PULSE MODE PACIFIER TONE PROVIDES AUDIBLE INDICATION OF VALID KEY PRESSED IN A BUZZER OR/AND IN THE EARPHONE TIMED PABX PAUSE / 10PPS PULSE RATE MAKE/BREAK RATIO : 40/60 (ST3917A) AND 33/67 (ST3917B) 4 SELECTABLE OPTIONS ON FLASH DURATION AND SOFTSWITCH INHIBITION IN ONE OF THE OPTION WITH 100ms FLASH TIMING 2 SELECTABLE OPTIONS : TRANSMIT MUTE TOGETHER WITH LED FOR KEYBOARD ILLUMINATION OR LED FOR TONE MODE INDICATION CONTINUOUS TONE FOR EACH DIGIT UNTIL KEY RELEASE USES INEXPENSIVE 3.

General Description

The device consists of the speech and the dialer functions.

It provides the DC line interface circuit that terminates the telephone line, analog amplifier for speech transmission and necessary signals for either DTMF and pulse dialing.

When mated with a tone ringer, a complete telephonecan be producedwith just two ICs.

Key Features

  • provided by the PABX or central office. The PAUSE key stores a timed pause in the number sequence. Redial is then delayed until an outside line can be accessed or some other activities occur before normal signalling resumes. A LND key automatically redials the last number dialed. Adedicatedpin MU/MFI is used to select the muting for transmit amplifier and lighted dial LED for keyboard illumination or a LEDindicator for tonemode indication. The SEL pin allows selection of any one of the four poss.

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ST3938A Distributor