MX909A View Datasheet(PDF) - CML Microsystems Plc

Part Name

Description

Manufacturer

MX909A

GMSK Modem Data Pump

CML Microsystems Plc 

COMMUNICATION SEMICONDUCTORS

DATA BULLETIN

MX909A

GMSK Modem Data Pump

PRELIMINARY INFORMATION

• GMSK Modulation

• RX or TX up to 19.2k bits/sec

• Full Data Packet Framing

• Mobitex¥ Compatible

• Flexible Operating Modes

• Host µC Interface

• Low Power 3.3V/5.0V Operation

• 24-Pin Small Form Package Option

RADIO

MODULATOR

RF

DISCRIMINATOR

ANALOG TX

ANALOG RX

MX909A

MODEM

DATA

PUMP

DATA AND

CONTROL BUS

HOST µC

SYSTEM

APPLICATION

PROCESSING

The MX909A is a low power CMOS device containing all of the baseband signal processing and Medium

Access Control (MAC) protocol functions required for a high performance GMSK Wireless Packet Data

Modem. The MX909A interfaces with a host µC and radio modulation/demodulation circuits to deliver reliable

two-way transfer of application data over a wireless link.

The MX909A assembles application data received from the host µC, adds forward error correction (FEC), and

error detection (CRC) codes, time-spreads this data by interleaving (burst-error protection) and scrambles

(randomizes) the bit pattern. After automatically adding bit and frame sync codewords, the data packet is

converted into analog GMSK signals for modulating into the radio transmitter.

In the receive mode, the MX909A performs the reverse function using the analog signals from the receivers

discriminator. After error correction and removal of the packet overhead, the recovered application data is

supplied to the host µC. Any CRC detected residual uncorrected errors in the data will be flagged. Readout

of the SNR value during receipt of a packet is also provided.

The MX909A uses data block sizes and FEC/CRC algorithms compatible with the Mobitex¥ Wide Area

Network over-air standard. The format used is suitable for other private applications where the high-speed

transfer of data over narrow-band wireless links is required. The MX909A is programmable to operate at

standard bit-rates from a wide choice of XTAL/CLOCK frequencies.

The MX909A may be used with a 3.0V to 5.5V power supply and is available in the following packages:

24-pin SSOP (MX909ADS), 24-pin SOIC (MX909ADW), 24-pin PLCC (MX909ALH), and

24-pin PDIP (MX909AP).

¤2001 MX-COM, Inc.

www.mxcom.com Tel: 800 638 5577 336 744 5050 Fax: 336 744 5054

Doc. # 20480134.005

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by their respective companies.

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