FX489

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


Specifications

Exceeding the maximum rating can result in device damage. Operation of the device outside the operating limits is
not implied.
Supply voltage                                                     -0.3 to 7.0V
Input voltage at any pin (ref V_SS = 0V)                -0.3 to (V_DD + 0.3V)
Sink/source current (supply pins)                         +/- 30mA
(other pins)                                                           +/- 20mA
Total device dissipation @ T_AMB 25°C                  800mW Max.
Derating                                                                10mW/°C
Operating temperature range: FX489DW/P          -40°C to +85°C
Storage temperature range: FX489DW/P              -40°C to +85°C


Description

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 of FX489 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 of FX489 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.