GENERAL DESCRIPTION
The MSM7715 is a signal transmitting and receiving LSI device for applications such as telemeters. The MSM7715 uses a no-ringing communication mode. Built-in functions includes a 300 bps full-duplex modem complying with ITU-T V.21, a DTMF signal (PB signal) generator and receiver, and a call progress tone (CPT) detector. The answer tone (1650 Hz) generation can be accomplished with the built-in modem.
A meter terminal can be configured using this transmitting and receiving device along with the meter, NCU, and controller.

FEATURES
• 3 V power supply. (Voltage range is 2.5 V to 3.6 V.)
• Selectable modes, including DTMF signal sending mode, DTMF signal receiving mode, and V.21 modem answer/originate mode.
• For DTMF signal reception, support for normal detection mode or high-speed detection mode.
• For call progress tone detection, support for rectangular wave output or detection output.
• DTMF signal receiving output, which is in a 3-state mode, is able to be connected externally with the DTMF signal sending 4-bit input.
• Analog loopback test and remote digital loopback test supported.
• Dedicated pins for modem sending/receiving data, carrier detection, sending request, and call progress tone detection.
• Independent external adjustment of the analog signal using the modem signal and DTMF signal.
• External adjustment of the carrier detection level.
• Internal 3.579545 MHz crystal oscillation circuit.
• Power-down mode
• Package:
    44-pin plastic QFP (QFP44-P-910-0.80-2K) (Product name : MSM7715GS-2K)