User Guide

STLC4550 implements 802.11b/g WLAN radio for embedded, low-power and small form factor mobile

applications. STLC4550 conforms to the IEEE 802.11b/g protocols operating in 2.4 GHz band supporting OFDM

data rates of 54, 48, 36, 24, 18, 12, 9, and 6 Mbps as well as CCK data rates of 11 and 5.5 Mbps and legacy

data rates of 2 and 1 Mbps. IEEE802.11e/i protocol extensions are included to implement quality of service

(QoS) and security functions.

STLC4550 has a fully integrated radio chip including a direct-conversion transceiver, RF synthesizer and VCO,

and high-speed data converters. Digital interface is used for transferring the sampled data between radio

and baseband chip. The baseband chip implements OFDM/CCK digital baseband processor and ARM9- based

MAC with internal SRAM memories. The baseband includes required logic and interfaces to enable time-shared

simultaneous use of BT and WLAN.

The energy management unit integrates required power management functions to operate the system from

VBAT (3.0 – 5.5 V). The EM unit generates 1.2 V digital core voltage, two 1.8 V supplies for RF and 2.8 V LDO

for PA bias supply. The EM unit also integrates power-on reset circuitry and level-shifters for RF front-end

GaAs switches.

Host interface is provided by a flexible serial interface (SPI) supporting clock frequency upto 48 MHz. The

maximum usable SPI clock rate depends on the host side clocking options and timing requirements. Typically

rates of 14 – 24 MHz are achieved. WLAN/BT coexistence interface enables automatic time shared usage of

WLAN and Bluetooth.

The system uses 38.4 MHz reference clock. In this device dedicated oscillator circuit for WLAN and Bluetooth

reference clock is used. Low power sleep mode operation is enabled using 32768Hz low speed clock and

energy management stand-by state.

WLAN RFMD RF5924 front end module is used. Power amplifier, RF-switches and baluns are integrated to

FEM. The PA includes power detector for closed-loop power control purposes. WLAN/BT bandpass filter is

external ceramic filter.

RM-313

System Module

Issue 1 COMPANY CONFIDENTIAL Page 6 –13