CMX469A

CML Microcircuits COMMUNICATION SEMICONDUCTORS CMX469A 1200/2400/4800 Baud FFSK/MSK Modem D/469A/3 June 2009 Features Full-Duplex FFSK/MSK Modem with Separate Rx and Tx Enable Functions Pin Selectable Data Rates: 1200, 2400 or 4800 Baud Pin Selectable Xtal/Clock Inputs: 1.008MHz or 4.032MHz Clock Recovery Facility Carrier Detect Facility Low Power Operation (2.0mA typ. at 3.0V) Applications Data-Over Radio Personal/Cordless Telephone Radio and General Applications Narrowband Coax Data Channels Two Way Radio (MPT1327) Signalling Portable Data Terminals 1.1 Brief Description The CMX469A is a single-chip CMOS LSI circuit which operates as a full-duplex 1200, 2400 or 4800 baud FFSK/MSK modem. The mark and space frequencies are 1200/1800, 1200/2400 and 2400/4800 Hz respectively. Tone frequencies are phase continuous; transitions occur at the zero crossing point. A common Xtal oscillator with a choice of two clock frequencies (1.008MHz or 4.032MHz) provides baud-rate, transmit frequencies, and Rx and Tx synchronization. The transmitter and receiver operate entirely independently, including the individual section powersave functions. The CMX469A includes on-chip circuitry for Carrier Detect and Rx Clock recovery, both of which are made available as output pins. Rx, Tx and Carrier Detect paths contain bandpass filters to optimise signal conditions in each section of the modem. The CMX469A demonstrates good sensitivity and bit-error-rate under adverse signa...