Consumer Microcircuits Limited FX949L6, FX949L4 Datasheet

CML Semiconductor Products

CDPD Wireless Modem Data Pump FX949

D/949/5 March 1996

1.0 Features Advance Information

•• 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

1.1 Brief 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.

 1996 Consumer Microcircuits Limited

CDPD Wireless Modem Data Pump FX949

CONTENTS

Section Page

1.0 Features..........................................................................................................1

1.1 Brief Description............................................................................................1

1.2 Block Diagram................................................................................................3

1.3 Signal List.......................................................................................................4

1.4 External Components....................................................................................6

1.5 General Description.......................................................................................9

1.5.1 Software Description ....................................................................... 9

1.6 Application Notes........................................................................................14

1.6.1 General..........................................................................................14

1.6.2 Transmitter (reverse channel).......................................................14

1.6.3 Receiver (forward channel)...........................................................15

1.6.4 Timer .............................................................................................16

1.7 Performance Specification .........................................................................18

1.7.1 Electrical Performance .................................................................. 18

1.7.2 Packaging......................................................................................23

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CDPD Wireless Modem Data Pump FX949

1.2 Block Diagram

Figure 1 Block Diagram

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CDPD Wireless Modem Data Pump FX949

µ

µ

1.3 Signal List

PackageL4Package

L6

Signal Description

Pin No. Pin No. Name Type

2 8 D0 BI )
3 9 D1 BI )
4 10 D2 BI )
5 11 D3 BI

) 8-bit bidirectional tristate
7 12 D4 BI ) data lines.
8 13 D5 BI )
9 14 D6 BI )

10 15 D7 BI )
12 17 V

DD

Power The positive supply rail. Levels and voltages are

dependent upon this supply. This pin should be

decoupled to V

13 18 V

BIAS

O/P A bias line for the internal circuitry, held at

½ V

capacitor mounted close to the device pins (see

Figures 2 and 3).

14 19 RX SIGNAL

FEEDBACK

O/P The 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

15 20 RX SIGNAL I/P The 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

.
18 23 TX SIGNAL O/P The inverted Tx signal output from the modem.
20 24 V

ss

Power The negative supply rail (ground).
26 31 XTALN O/P The inverted output of the on-chip oscillator.
27 32 CLOCK/XTAL I/P The input to the on-chip oscillator, for external

Xtal circuit or clock.

32 36 IRQN O/P A '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.

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CDPD Wireless Modem Data Pump FX949

µ

µ

PackageL4Package

L6

Signal Description

Pin No. Pin No. Name Type

33 37 CSN I/P Chip Select. An active low logic level input to the

modem, used to enable a data read or write
operation.

34 38 WRN I/P Write. An active low logic level input used to

control the writing of data into the modem from
the controlling

P.

35 39 RDN I/P Read. An active low logic level input used to

control the reading of data from the modem into
the controlling

P.

38 41 A6 I/P )
39 42 A5 I/P )
43 1 A4 I/P )
44 2 A3 I/P ) 7 logic level modem register address select
45 3 A2 I/P ) inputs.
46 4 A1 I/P )
47 5 A0 I/P )

1, 6,
11, 19,
24, 30,
36, 37,

6, 7,
16, 28,
30, 40,

43, 44

40, 41,

42, 48

21, 22,
23, 25,
28, 29,

31

25, 26,
27, 29,
33, 34,

35

Notes: I/P = Input

O/P = Output
BI = Bidirectional

)
)
) No internal connection: leave open circuit.
)
)
)

)
) Internally connected: leave open circuit.
)
)

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1.4 External Components

Figure 2 Recommended External Components (L4)

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Figure 3 Recommended External Components (L6)

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CDPD Wireless Modem Data Pump FX949

Figure 4 Internal Block Diagram

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