FX489 Datasheet, PDF (1/12 Pages) List of Unclassifed Manufacturers – GMSK Modem

CML Semiconductor Products
PRODUCT INFORMATION
FX489 ^{GMSK Modem}
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
V_BIAS
Tx
FILTER
V_BIAS
Tx OUT
Tx CLOCK
XTAL
ClkDIVA
ClkDIVB
CLOCK
DIVIDER
Rx DATA
EXTRACT
Rx DATA
BT
V_DD
Rx S/N
DETECTION
FX489 ^{Rx S/N}
RxHold
PLLacq
RxDCacq
Rx PS
Rx SIGNAL IN
Rx FEEDBACK
Rx CIRCUIT
CONTROL
V_BIAS
+
-
Fig.1 Functional Block Diagram
Brief Description
Rx
FILTER
Rx CLOCK
EXTRACT
Rx LEVEL
MEASURE
DOC1
DOC2
Rx CLOCK
V_SS
V_BIAS
NEW
40kbps
Modem
FX589
Pin/Function
Compatible
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.
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 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.
The FX489, a low-power CMOS microcircuit, is
available in both 24-pin plastic Small Outline (S.O.I.C)
and DIL packages.
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