••MES Full Duplex Operation••19.2kb/s GMSK Modulation
••Forward Channel Decoding••Sleep Timer Included
••Reverse Channel Encoding••3.3V and 5V Applications
••Error Detection and Syndrome Output••PCMCIA Package Option
1.1Brief Description
The FX949 is a low power CMOS integrated circuit which performs all of the real-time signal and data
format-management functions required for full-duplex operation of a CDPD Mobile End Station.
The FX949 interfaces directly with the analogue modulation and demodulation circuits of the radio and
the host radio/application processor bus.
It accepts application data from the processor, constructs a correct Reverse Channel packet containing
this data and converts the packet to GMSK analogue signals for transmission. In receive, Forward
Channel GMSK signals from the discriminator are demodulated, the packet disassembled, error
checked, and the recovered application data passed to the processor.
The FX949 is the cost, size, and power efficient alternative to DSP design solutions in high
performance OEM products for the Cellular Digital Packet Data wireless services.
) 8-bit bidirectional tristate
712D4BI) data lines.
813D5BI)
914D6BI)
1015D7BI)
1217V
DD
PowerThe positive supply rail. Levels and voltages are
dependent upon this supply. This pin should be
decoupled to V
1318V
BIAS
O/PA bias line for the internal circuitry, held at
½ V
capacitor mounted close to the device pins (see
Figures 2 and 3).
1419RX SIGNAL
FEEDBACK
O/PThe output of the Rx input amplifier and the input
to the Rx filter.
P interface
by a capacitor.
SS
. This pin must be decoupled by a
DD
1520RX SIGNALI/PThe inverting input to the Rx input amplifier.
16
17
21
22
DOC 1
DOC 2
O/P
O/P
) Connections to the Rx level measurement
) circuitry. A capacitor should be connected
) from each pin to V
SS
.
1823TX SIGNALO/PThe inverted Tx signal output from the modem.
2024V
ss
PowerThe negative supply rail (ground).
2631XTALNO/PThe inverted output of the on-chip oscillator.
2732CLOCK/XTALI/PThe input to the on-chip oscillator, for external
Xtal circuit or clock.
3236IRQNO/PA 'wire-ORable' output for connection to the
controlling
output has a low impedance pull down to V
P's Interrupt Request input. This
SS
when active and is high impedance when
inactive.
1996 Consumer Microcircuits Limited4D/949/5
CDPD Wireless Modem Data PumpFX949
µ
µ
PackageL4Package
L6
SignalDescription
Pin No.Pin No.NameType
3337CSNI/PChip Select. An active low logic level input to the
modem, used to enable a data read or write
operation.
3438WRNI/PWrite. An active low logic level input used to
control the writing of data into the modem from
the controlling
P.
3539RDNI/PRead. An active low logic level input used to
control the reading of data from the modem into
the controlling