Si4421 Universal ISM Band Si4421 FSK Transceiver PIN ASSIGNMENT DESCRIPTION Silicon Labs Si4421 is a single chip, low power, multi-channel FSK transceiver designed for use in applications requiring FCC or ETSI conformance for unlicensed use in the 433, 868 and 915 MHz bands. TM The Si4421 transceiver is a part of Silicon Labs EZRadio product line, which produces a flexible, low cost, and highly integrated solution that does not require production alignments. The chip is a complete analog RF and baseband transceiver including a multi-band PLL synthesizer with PA, LNA, I/Q down converter mixers, baseband filters This document refers to Si4421-IC rev A1. See www.silabs.com/integration for any applicable errata. and amplifiers, and an I/Q demodulator. All required RF functions are See back page for ordering information. integrated. Only an external crystal and bypass filtering are needed for operation. FEATURES The Si4421 features a completely integrated PLL for easy RF design, and its rapid settling time allows for fast frequency-hopping, bypassing Fully integrated (low BOM, easy design-in) multipath fading and interference to achieve robust wireless links. The No alignment required in production PLLs high resolution allows the usage of multiple channels in any of Fast-settling, programmable, high-resolution PLL synthesizer the bands. The receiver baseband bandwidth (BW) is programmable to Fast frequency-hopping capability High bit rate (up to 115.2 kbps in digital mode and 256 kbps accommodate various deviation, data rate and crystal tolerance in analog mode) requirements. The transceiver employs the Zero-IF approach with I/Q Direct differential antenna input/output demodulation. Consequently, no external components (except crystal Integrated power amplifier and decoupling) are needed in most applications. Programmable TX frequency deviation (15 to 240 kHz) The Si4421 dramatically reduces the load on the microcontroller with Programmable RX baseband bandwidth (67 to 400 kHz) the integrated digital data processing features: data filtering, clock Analog and digital RSSI outputs recovery, data pattern recognition, integrated FIFO and TX data Automatic frequency control (AFC) register. The automatic frequency control (AFC) feature allows the use Data quality detection (DQD) of a low accuracy (low cost) crystal. To minimize the system cost, the Internal data filtering and clock recovery Si4421 can provide a clock signal for the microcontroller, avoiding the RX synchron pattern recognition need for two crystals. SPI compatible serial control interface Clock and reset signals for microcontroller For low power applications, the Si4421 supports low duty cycle 16-bit RX Data FIFO operation based on the internal wake-up timer. Two 8-bit TX data registers Low power duty cycle mode FUNCTIONAL BLOCK DIAGRAM Standard 10 MHz crystal reference with on-chip tuning Wake-up timer 2.2 to 3.8 V supply voltage MIX I DCLK / AMP OC 7 CFIL / Low power consumption clk FFIT / 13 RF1 I/Q Data Filt LNA Self cal. FSK / data DEMOD CLK Rec 6 Low standby current (0.3 A) DATA / RF2 12 MIX nFFS Q AMP OC Compact 16 pin TSSOP package PA FIFO Supports very short packets (down to 3 bytes) Excellent temperature stability of the RF parameters PLL & I/Q VCO RSSI COMP DQD AFC with cal. Good adjacent channel rejection/blocking RF Parts BB Amp/Filt./Limiter Data processing units TYPICAL APPLICATIONS WTM CLK div Xosc LBD Controller Bias with cal. Home security and alarm Low Power parts Remote control, keyless entry 8 9 15 1 2 3 4 5 10 16 11 14 Wireless keyboard/mouse and other PC peripherals CLK XTL / ARSSI SDI SCK nSEL SDO nIRQ nRES nINT / VSS VDD REF VDI Toy controls Remote keyless entry Tire pressure monitoring Telemetry Personal/patient data logging Remote automatic meter reading 1 Si4421-DS rev 2.4r 0708 www.silabs.com Si4421 2