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PRODUCT INFORMATION

Obsolete Product - For Information Only

CML Semiconductor Products

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

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

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 communication systems conforming to DOC and

FCC spectrum limitations for 12.5kHz and 8,000 baud

at a BT of 0.3, and 12.5, 25.0, and 50.kHz channel

spacing and data rates of 4800, 9600 and 19,200

baud respectively at a BT of 0.5.

The Rx and Tx digital data interfaces are bit-serial

and synchronised to Rx and Tx data clocks generated

by the modem. Separate Rx and Tx Powersave/

Enable inputs allow for full- or half-duplex operation.

Rx input levels can be set by a suitable a.c. and

d.c. level adjusting circuit built, with external

components, 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 signal.

The FX489, a low-power CMOS microcircuit, is

available in both 24-pin plastic Small Outline (S.O.I.C)

and DIL packages.

Brief Description

Fig.1 Functional Block Diagram

FX489

Tx PS

Rx PS

BT

Tx DATA

ClkDIVA

PLLacq

RxDCacq

Rx SIGNAL IN

Rx FEEDBACK

ClkDIVB

XTAL/CLOCK

Tx ENABLE

XTAL

RxHold

+

-

DOC1

Rx CLOCK

Tx CLOCK

Tx OUT

Rx DATA

Rx S/N

DOC2

DATA RETIME

&

LEVEL SHIFT

Tx

FILTER

CLOCK

DIVIDER

Rx CIRCUIT

CONTROL

Rx

FILTER

Rx LEVEL

MEASURE

Rx CLOCK

EXTRACT

Rx S/N

DETECTION

Rx DATA

EXTRACT

NEW

40kbps

Modem

FX589

Pin/Function

Compatible