FX489 Datasheet | CML

Features Full-Duplex Gaussian Minimum Shift Keying Selectable BT (0.3 or 0.5) Meets RAM - MOBITEX Specification Data Rates From 4000bits/s to 19200bits/s Serial Rx and Tx Data Interfaces Obsolete Product - For Information Only Rx and Tx Data Clock Generation Rx Signal Tracking Controls Rx S/N Indication Separate Rx and Tx Powersave Inputs Wireless Modem, Radio Telemetry and Data Terminal Applications Tx ENABLE Tx PS Tx DATA XTAL/CLOCK DATA RETIME & LEVEL SHIFT VBIAS Tx FILTER VBIAS Tx OUT Tx CLOCK XTAL Clk DIVA Clk DIVB CLOCK DIVIDER Rx DATA EXTRACT Rx DATA Rx S/N DETECTION FX489 Rx S/N Rx Hold PLLacq Rx DCacq Rx PS Rx SIGNAL IN Rx FEEDBACK Rx CIRCUIT CONTROL VBIAS + - Fig.1 Functional Block Diagram Brief Description Rx FILTER Rx CLOCK EXTRACT Rx LEVEL MEASURE DOC1 DOC2 Rx CLOCK VSS VBIAS NEW 40kbps Modem FX589 Pin/Function patible The FX489 is a single-chip modem employing Gaussian Minimum Shift Keying (GMSK) modulation. Having a pin selectable BT of 0.3 or 0.5, the FX489 may be employed at data rates of between 4,000bits/s and 19,200bits/s; for use in FM radio-data links and data munication systems conforming to DOC and FCC spectrum limitations for 12.5k Hz and 8,000 baud at a BT of 0.3, and 12.5, 25.0, and 50.k Hz channel spacing and data rates of 4800, 9600 and 19,200 baud respectively at a BT of 0.5. Rx input levels can be set by a suitable a.c. and d.c. level adjusting circuit built, with external ponents, around an on-chip Rx input amplifier. Acquisition, lock and hold of Rx data signals is made easier and faster by the use of Rx Control Inputs to clamp, detect and/or hold input data levels and can be set by the µProcessor as required. Indication is available, from the Rx S/N output, as to the quality of the received...