Si4020 Universal ISM
Band FSK Transmitter
DESCRIPTION
Silicon Labs’ Si4020 is a single chip, low power, multi-channel FSK
transmitter designed for use in applications requiring FCC or ETSI
conformance for unlicensed use in the 315, 433, 868, and 915 MHz bands.
Used in conjunction with IA4320, Silicon Labs’ FSK receiver, the Si4020
transmitter feature EZRadio
TM
technology, which produces a flexible, low
cost, and highly integrated solution that does not require production
alignments. All required RF functions are integrated. Only an external crystal
and bypass filtering are needed for operation.
The Si4020 features a completely integrated PLL for easy RF design, and its
rapid settling time allows for fast frequency hopping, bypassing multipath
fading and interference to achieve robust wireless links. In addition, highly
stable and accurate FSK modulation is accomplished by direct closed-loop
modulation with bit rates up to 256 kbps. The PLL’s high resolution allows
the use of multiple channels in any of the bands.
The integrated power amplifier of the transmitter has an open-collector
differential output that directly drive a loop antenna with programmable
output level. No additional matching network is required. An automatic
antenna tuning circuit is built in to avoid costly trimming procedures and de-
tuning due to the “hand effect”.
For low-power applications, the device supports automatic activation from
sleep mode. Active mode can be initiated by several wake-up events (on-chip
timer timeout, low supply voltage detection, or activation of any of the four
push-button inputs).
The Si4020’s on-chip digital interface supports both a microcontroller mode
and an EEPROM mode. The latter allows complete data transmitter
operation without a microcontroller (both control commands and data are
read from the EEPROM). Any wake-up event can start a transmission of the
corresponding data stored in the EEPROM.
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Si4020
PIN ASSIGNMENT
Microcontroller Mode
EEPROM Mode
This document refers to Si4020-IC Rev
I1.
See www.silabs.com/integration for any applicable
errata. See back page for ordering information.
FEATURES
Fully integrated (low BOM, easy design-in)
No alignment required in production
Fast settling, programmable, high-resolution PLL
Fast frequency hopping capability
Stable and accurate FSK modulation with programmable
deviation
High bit rate (up to 256 kbps)
Direct loop antenna drive
Automatic antenna tuning circuit
Programmable output power level
Alternative OOK support
EEPROM mode supported
SPI bus for applications with microcontroller
Clock output for microcontroller
Integrated programmable crystal load capacitor
Power-saving sleep mode
Multiple event handling options for wake-up activation
Push-button event handling with switch de-bounce
Wake-up timer
Low battery detection
2.2 to 5.4 V supply voltage
Low power consumption
Low standby current (0.3 µA)
Compact 16-pin TSSOP package
FUNCTIONAL BLOCK DIAGRAM
CRYSTAL
OSCILLATOR
REFERENCE
RFP
SYNTHESIZER
RFN
XTL
CLOCK
FREQUENCY
LOAD CAP
MOD
LOW
BATTERY
DETECT
LOW BAT
TRESHOLD
CONTROLLER
LEVEL
OOK
nIRQ/nLBD
CLK/SDO
SDI
SCK
TYPICAL APPLICATIONS
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Remote control
Home security and alarm
Wireless keyboard/mouse and other PC peripherals
Toy control
Remote keyless entry
Tire pressure monitoring
Telemetry
Personal/patient data logging
Remote automatic meter reading
VDD
VSS
TIMEOUT
WAKE-UP
TIMER
PERIOD
nSEL
FSK
PB1 PB2 PB3 PB4
1
Si4020-DS Rev 1.9r 0308
www.silabs.com/integration
SILABS [ SILICON LABORATORIES ]
