CMX469A CML Microcircuits 1200/2400/4800 Baud COMMUNICATION SEMICONDUCTORS FFSK/MSK Modem D/469A/3 June 2009 Features Applications Full-Duplex FFSK/MSK Modem with Data-Over Radio Separate Rx and Tx Enable Functions Personal/Cordless Telephone Pin Selectable Data Rates: Radio and General Applications 1200, 2400 or 4800 Baud Narrowband Coax Data Channels Pin Selectable Xtal/Clock Inputs: Two Way Radio (MPT1327) Signalling 1.008MHz or 4.032MHz Portable Data Terminals Clock Recovery Facility Carrier Detect Facility Low Power Operation (2.0mA typ. at 3.0V) 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 signal conditions. The Carrier Detect time constant is set by an external capacitor, so that the product s performance can be optimised in high noise environments. This low-power device operates from a single supply between 2.7V and 5.5V, requires few external components and is available in a wide variety of plastic packages. 2009 CML Microsystems Plc 1200/2400/4800 Baud FFSK/MSK Modem CMX469A CONTENTS Section Page 1.0 Features and Applications .....................................................................1 1.1 Brief Description .....................................................................................1 1.2 Block Diagram .........................................................................................3 1.3 Signal List ................................................................................................4 1.4 External Components.............................................................................6 1.5 General Description................................................................................7 1.6 Application Notes....................................................................................8 1.6.1 Rx Enable....................................................................................8 1.6.2 Operational Data Rate Configurations.....................................8 1.6.3 Test Set Up .................................................................................8 1.6.4 Synchronous Modem Design Considerations ........................9 1.7 Performance Specification...................................................................11 1.7.1 Electrical Performance ............................................................11 1.7.2 Packaging .................................................................................17 2009 CML Microsystems Plc 2 D/469A/3