Si4020 Universal ISM Band FSK Transmitter Si4020 PIN ASSIGNMENT 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 EZRadioTM 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. Microcontroller Mode 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 detuning 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. FUNCTIONAL BLOCK DIAGRAM XTL CRYSTAL OSCILLATOR REFERENCE RFP SYNTHESIZER RFN CLOCK FREQUENCY LOAD CAP LEVEL OOK MOD LOW BATTERY DETECT nIRQ/nLBD LOW BAT TRESHOLD CLK/SDO CONTROLLER SDI SCK VDD VSS TIMEOUT WAKE-UP TIMER nSEL PERIOD FSK PB1 PB2 PB3 PB4 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 TYPICAL APPLICATIONS • • • • • • • • • 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 1 Si4020-DS Rev 1.9r 0308 www.silabs.com/integration Si4020 DETAILED DESCRIPTION The Si4020 FSK transmitter is designed to cover the unlicensed frequency bands at 315, 433, 868, and 915 MHz. The device facilitates compliance with FCC and ETSI requirements. PLL The programmable PLL synthesizer determines the operating frequency, while preserving accuracy based on the on-chip crystal-controlled reference oscillator. The PLL’s high resolution allows the usage of multiple channels in any of the bands. The FSK deviation is selectable (from 30 to 240 kHz with 30 kHz increments) to accommodate various bandwidth, data rate and crystal tolerance requirements, and it is also highly accurate due to the direct closed-loop modulation of the PLL. The transmitted digital data can be sent asynchronously through the FSK pin or over the control interface using the appropriate command. The RF VCO in the PLL performs automatic calibration, which requires only a few microseconds. To ensure proper operation in the programmed frequency band, the RF VCO is automatically calibrated upon activation of the synthesizer. If temperature or supply voltage change significantly or operational band has changed, VCO recalibration is recommended.. Recalibration can be initiated at any time by switching the synthesizer off and back on again. RF Power Amplifier (PA) The power amplifier has an open-collector differential output and can directly drive a loop antenna with a programmable output power level. An automatic antenna tuning circuit is built in to avoid costly trimming procedures and the so-called “hand effect.” The transmitters can operate in On-Off Keying (OOK) mode by switching the power amplifier on and off. When the appropriate control bit is set using the Power Setting Command, the FSK pin becomes an enable input (active high) for the power amplifier. Crystal Oscillator The chip has a single-pin crystal oscillator circuit, which provides a 10 MHz reference signal for the PLL. To reduce external parts and simplify design, the crystal load capacitor is internal and programmable. Guidelines for selecting the appropriate crystal can be found later in this datasheet. The transmitters can supply the clock signal for the microcontroller, so accurate timing is possible without the need for a second crystal. When the chip receives a Sleep Command from the microcontroller and turns itself off, it provides several further clock pulses (“clock tail”) for the microcontroller to be able to go to idle or sleep mode. The length of the clock tail is programmable. Low Battery Voltage Detector Wake-Up Timer The wake-up timer has very low current consumption (1.5 uA typical) and can be programmed from 1 ms to several days with an accuracy of ±5%. It calibrates itself to the crystal oscillator at every startup. When the oscillator is switched off, the calibration circuit switches on the crystal oscillator only long enough for a quick calibration (a few milliseconds) to facilitate accurate wake-up timing. Event Handling In order to minimize current consumption, the device supports sleep mode. Active mode can be initiated by several wake-up events: timeout of wake-up timer, detection of low supply voltage, pressing any of the four push-button inputs, or through the serial interface. The push-button inputs can be driven by a logic signal from a microcontroller or controlled directly by normally open switches. Pull-up resistors are integrated. If any wake-up event occurs, the wake-up logic generates an interrupt, which can be used to wake up the microcontroller, effectively reducing the period the microcontroller has to be active. The cause of the interrupt can be read out from the transmitters by the microcontroller through the nIRQ pin. Interface An SPI compatible serial interface lets the user select the operating frequency band and center frequency of the synthesizer, polarity and deviation of FSK modulation, and output power level. Division ratio for the microcontroller clock, wake-up timer period, and low battery detector threshold are also programmable. Any of these auxiliary functions can be disabled when not needed. All parameters are set to default after poweron; the programmed values are retained during sleep mode. EEPROM Mode In simple applications, the on-chip digital controller provides the transmitters with direct interface to a serial (SPI) EEPROM. In this case, no external microcontroller is necessary. Wake-up events initiate automatic readout of the assigned command sequence from EEPROM memory. For every event, there is a dedicated starting address available in the EEPROM. Programming the EEPROM is very simple. Any control command can be programmed in the EEPROM sequentially (same as in microcontroller mode). The internal power-on reset (POR) is a dedicated event, which can be used to program the basic settings of the transmitters. In this case the chip starts to read out the preprogrammed data from the 00h address in EEPROM. Data can be transmitted with the help of the Data Transmit Command, which tells the transmitters how many bytes must be transmitted. The whole process finishes with a Sleep Command. The low battery voltage detector circuit monitors the supply voltage and generates an interrupt if it falls below a programmable threshold level. The detector circuit has 50 mV hysteresis. 2 Si4020 PACKAGE PIN DEFINITIONS, MICROCONTROLLER MODE Pin type key: D=digital, A=analog, S=supply, I=input, O=output, IO=input/output Microcontroller Mode Pin Assignment Pin Name Type 1 SDI DI Function Data input of serial control interface 2 SCK DI Clock input of serial control interface 3 nSEL DI Chip select input of serial control interface (active low) 4 PB1 DI Push-button input #1 (active low with internal pull-up resistor) 5 PB2 DI Push-button input #2 (active low with internal pull-up resistor) 6 PB3 DI Push-button input #3 (active low with internal pull-up resistor) 7 PB4 DI Push-button input #4 (active low with internal pull-up resistor) 8 CLK DO Microcontroller clock (1 MHz-10 MHz) 9 XTL AIO Crystal connection (other terminal of crystal to VSS) 10 VSS S 11 MOD DI Ground reference Connect to logic high (microcontroller mode) 12 RFN AO Power amplifier output (open collector) Power amplifier output (open collector) 13 RFP AO 14 nIRQ DO 15 VDD S Positive supply voltage 16 FSK DI Serial data input for FSK modulation Interrupt request output for microcontroller (active low) and status read output 3 Si4020 Typical Application, Microcontroller Mode VDD C1 2.2µF C2 10nF C3 D1 LED RED R1 470 GND OPTIONAL GP3 GP6 To other GP7 circuits GP8 GP4 MICRO CONTROLLER GP9 GP2 SDI GP1 SCK nSEL GP0 GP5 CLKin (EC osc. mode) 16 15 FSK 3 14 nIRQ PB1 4 13 RFP PB2 PB3 5 6 12 11 RFN PB4 7 10 MOD VSS CLK 8 9 XTL IA4220 Antenna VDD X1 10MHz S4 S3 S2 S1 GND 1 2 GND GND OPTIONAL GND Note: For detailed information about the supply decoupling capacitors see page 6. 4 Si4020 PACKAGE PIN DEFINITIONS, EEPROM MODE Pin type key: D=digital, A=analog, S=supply, I=input, O=output, IO=input/output EEPROM Mode Pin Assignment Pin Name Type Function 1 SDI DI 2 SCK DO Data input of serial control interface Clock output of serial control interface 3 nSEL DO Chip select output of serial control interface (active low) 4 PB1 DI Push-button input #1 (active low with internal pull-up resistor) 5 PB2 DI Push-button input #2 (active low with internal pull-up resistor) 6 PB3 DI Push-button input #3 (active low with internal pull-up resistor) 7 PB4 DI Push-button input #4 (active low with internal pull-up resistor) 8 SDO DO Data output of serial control interface 9 XTL AIO Crystal connection (other terminal of crystal to VSS) 10 VSS S 11 MOD DI Connect to logic low (EEPROM mode) 12 RFN AO Power amplifier output (open collector) Ground reference 13 RFP AO Power amplifier output (open collector) 14 nLBD DO Low battery voltage detector output (active low) 15 VDD S Positive supply voltage 16 FSK DI Not used, connect to VDD or VSS 5 Si4020 Typical Application, EEPROM Mode VDD C3 C2 10nF C1 2.2µF D1 LED RED R1 470 GND nCS 1 SO nWP 2 GND 4 EEPROM 25AA080 3 8 VCC 7 6 HOLD SCK 5 SI GND OPTIONAL SD I SCK 1 16 FSK 2 15 nSEL 3 14 PB1 PB2 4 5 13 12 VDD nLBD RFP PB3 6 11 MOD PB4 7 10 VSS SD0 8 9 XTL IA4220 Antenna x RFN S4 S3 S2 S1 X1 10MHz GND GND GND Recommended supply decoupling capacitor values C2 and C3 should be 0603 size ceramic capacitors to achieve the best supply decoupling. The capacitor values are valid for both stand-alone and microcontroller mode. Band [MHz] 315 433 868 915 C1 2.2µF 2.2µF 2.2µF 2.2µF C2 10nF 10nF 10nF 10nF C3 390pF 220pF 47pF 33pF 6 Si4020 GENERAL DEVICE SPECIFICATIONS All voltages are referenced to Vss, the potential on the ground reference pin VSS. Absolute Maximum Ratings (non-operating) Symbol Parameter Min Max Units Vdd Positive supply voltage Vin Voltage on any pin except open collector outputs -0.5 6.0 V -0.5 Vdd+0.5 Voc V Voltage on open collector outputs -0.5 6.0 V Iin Input current into any pin except VDD and VSS -25 25 mA ESD Electrostatic discharge with human body model Tst Storage temperature Tld Lead temperature (soldering, max 10 s) -55 1000 V 125 ºC 260 ºC Recommended Operating Range Symbol Parameter Min Max Units Vdd Positive supply voltage 2.2 5.4 V Voc Voltage on open collector outputs (Max 6.0 V) Vdd - 1 Vdd + 1 V Top Ambient operating temperature -40 85 ºC ELECTRICAL SPECIFICATION (Min/max values are valid over the whole recommended operating range, typical conditions: Top = 27 oC; Vdd = Voc = 2.7 V) DC Characteristics Symbol Idd_TX_0 Idd_TX_PMAX Ipd Parameter Supply current (TX mode, Pout = 0 dBm) Supply current (TX mode, Pout = Pmax) Standby current in sleep mode Conditions/Notes Min Typ 315 MHz band 9 433 MHz band 10 868 MHz band 12 915 MHz band 13 315 MHz band 11 433 MHz band 12 868 MHz band 14 Max Units mA mA 915 MHz band 15 All blocks disabled (Note 1) 0.3 µA Iwt Wake-up timer current consumption 1.5 µA Ilb Low battery detector current consumption 0.5 µA Ix Idle current 1.5 mA Vlba Low battery detection accuracy Vlb Low battery detector threshold Vil Digital input low level Vih Digital input high level Iil Digital input current Only crystal oscillator is on 75 Programmable in 0.1 V steps 2.2 mV 5.3 V 0.3*Vdd V 1 µA 1 µA 0.4 V 0.7*Vdd Vil = 0 V -1 -1 Iih Digital input current Vih = Vdd, Vdd = 5.4 V Vol Digital output low level Iol = 2 mA Voh Digital output high level Ioh = -2 mA Vdd-0.4 V V Note for table above is on page 7. 7 Si4020 AC Characteristics Symbol fref fo Parameter PLL reference frequency Output frequency (programmable) Conditions/Notes Crystal operation mode is parallel (Note 2) Min Typ 8 10 Max Units 12 MHz 315 MHz band, 2.5 kHz resolution 310.24 319.75 433 MHz band, 2.5 kHz resolution 430.24 439.75 868 MHz band, 5.0 kHz resolution 860.48 879.51 915 MHz band, 7.5 kHz resolution 900.72 929.27 MHz tlock PLL lock time Frequency error < 10 kHz after 10 MHz step tsp PLL startup time After turning on from idle mode, with crystal oscillator already stable IOUT Open collector output current (Note 3) At all bands PmaxL Available output power (315 and 433 MHz band) With optimal antenna impedance (Note 4) 3 dBm PmaxH Available output power (868 and 915 MHz band) With optimal antenna impedance (Note 4) 1 dBm Pout Typical output power Selectable in 3 dB steps (Note3) Psp Spurious emission At max power with loop antenna (Note 5) Co Output capacitance (set by the automatic antenna tuning circuit) Qo Quality factor of the output capacitance Lout Output phase noise BRFSK FSK bit rate 256 kbps BROOK OOK bit rate 512 kbps 20 0.1 Pmax-21 µs 250 µs 2.5 mA Pmax dBm -50 dBc At low bands 1.5 2.3 3.1 At high bands 1.6 2.2 2.8 16 18 22 100 kHz from carrier -75 1 MHz from carrier -85 pF dBc/Hz dffsk FSK frequency deviation Programmable in 30 kHz steps 30 240 kHz Cxl Crystal load capacitance See Crystal Selection Guidelines Programmable in 0.5 pF steps, tolerance +/- 10% 8.5 16 pF tPOR Internal POR timeout (Note 6) After Vdd has reached 90% of final value 100 ms tsx Crystal oscillator startup time Crystal ESR < 100 Ohms (Note 7) 5 ms tPBt Wake-up timer clock accuracy Crystal oscillator must be enabled to ensure proper calibration at startup (Note 7) twake-up Programmable wake-up time Cin, D Digital input capacitance tr, f Digital output rise/fall time 1 +/-10% 1 15 pF pure capacitive load ms 2 · 10 9 ms 2 pF 10 ns All notes for table above are on page 7. 8 Si4020 Note 1: Using a CR2032 battery (225 mAh capacity), the expected battery life is greater than 2 years using a 60-second wake-up period for sending 100 byte packets in length at 19.2 kbps with +3 dBm output power in the 915 MHz band. Note 2: Using anything but a 10 MHz crystal is allowed but not recommended because all crystal-referred timing and frequency parameters will change accordingly. Note 3: Adjustable in 8 steps. Note 4: Optimal antenna admittance/impedance for the Si4020: Yantenna [S] Zantenna [Ohm] Lantenna [nH] 315 MHz 9.4E-4 - j4.5E-3 43 + j214 112.00 434 MHz 8.4E-4 - j6.25E-3 21 + j157 59.00 868 MHz 1.15E-3 - j1.2E-2 7.9 + j83 15.30 915 MHz 1.2E-3 - j1.25E-2 7.6 + j79 13.90 Note 5: With selective resonant antennas (see: Application Notes available from http://www.silabs.com/integration). Note 6: During this period, no commands are accepted by the chip. For detailed information see the Reset modes section. Note 7: The crystal oscillator start-up time strongly depends on the capacitance seen by the oscillator. Using low capacitance and low ESR crystal is recommended. When designing the PCB layout keep the trace connecting to the crystal short to minimize stray capacitance. 9 Si4020 TYPICAL PERFORMANCE DATA Unmodulated RF Spectrum The output spectrum is measured at different frequencies. The output is loaded with 50 Ohms through a matching network. At 315 MHz At 433 MHz 15:18:59 Oct 29, 2003 15:37:47 Dec 15, 2003 Ref -10 dBm Samp Log 10 dB/ Mkr1 315.0010 MHz -22.7 dBm Atten 5 dB 1 VAvg 100 W1 S2 S3 FC AA Ref -10 dBm Samp Log 10 dB/ Mkr1 434.0630 MHz -23.41 dBm #Atten 5 dB 1 VAvg 100 W1 S2 S3 FC AA Center 315 MHz Res BW 10 kHz VBW 10 kHz Span 2 MHz Sweep 40.74 ms (2001 pts) Center 434.1 MHz Res BW 10 kHz VBW 10 kHz At 915 MHz At 868 MHz 15:20:49 Oct 29, 2003 Ref -10 dBm Samp Log 10 dB/ 15:28:02 Dec 15, 2003 Mkr1 868.0680 MHz -23.23 dBm #Atten 5 dB 1 VAvg 100 W1 S2 S3 FC AA Center 868.1 MHz Res BW 10 kHz Span 2 MHz Sweep 40.74 ms (2001 pts) Ref -10 dBm Samp Log 10 dB/ Mkr1 915.0000 MHz -24.63 dBm Atten 5 dB 1 VAvg 100 W1 S2 S3 FC AA VBW 10 kHz Span 2 MHz Swee p 40.74 ms (2001 pts) Center 915 MHz Res BW 10 kHz VBW 10 kHz Span 2 MHz Sweep 40.74 ms (2001 pts) 10 Si4020 Modulated RF Spectrum At 433 MHz with 180 kHz Deviation at 64 kbps At 868 MHz with 180 kHz Deviation at 64 kbps 15:43:45 Oct 29, 2003 15:46:09 Oct 29, 2003 Ref -10 dBm #Peak Log 10 dB/ Ref -10 dBm #Peak Log 10 dB/ Atten 5 dB Atten 5 dB VAvg 100 W1S2 S3 FC AA VAvg 100 W1S2 S3 FC AA Center 434 MHz Res BW 10 kHz VBW 100 kHz Span 2 MHz Sweep 20.07 ms (2001 pts) Center 868 MHz Res BW 10 kHz Spurious RF Spectrum With 10 MHz CLK Output Enabled at 433 MHz p Antenna Tuning Characteristics 750–970 MHz 16:29:03 Jun 17, 2003 Ref 0 dBm #Peak Log 10 dB/ 16:54:54 Mar 11, 2003 Mkr1 ∆ 20.0 MHz -55.11 dB Atten 10 dB 1R Ref -36 dBm Peak Log 1 dB/ Marker ∆ 20.000000 MHz -55.11 dB Mkr1 915.0 MHz -37.62 dBm #Atten 0 dB * 1 Marker 915.000000 MHz -37.62 dBm W1S2 S3 FC AA Center 434.8 MHz #Res BW 3 kHz Span 2 MHz Sweep 20.07 ms (2001 pts) VBW 100 kHz 1 #VBW 300 Hz Span 50 MHz Sweep 45.47 s (401 pts) V1 M2 S3 FC AA Start 700 MHz #Res BW 1 MHz VBW 1 MHz Stop 1.05 GHz Sweep 50 ms (401 pts) The antenna tuning characteristics was recorded in “max-hold” state of the spectrum analyzer. During the measurement, the transmitters were forced to change frequencies by forcing an external reference signal to the XTL pin. While the carrier was changing the antenna tuning circuit switched trough all the available states of the tuning circuit. The graph clearly demonstrates that while the complete output circuit had about a 40 MHz bandwidth, the tuning allows operating in a 220 MHz band. In other words the tuning circuit can compensate for 25% variation in the resonant frequency due to any process or manufacturing spread. 11 Si4020 CONTROL INTERFACE Commands to the transmitters are sent serially. Data bits on pin SDI are shifted into the device upon the rising edge of the clock on pin SCK whenever the chip select pin nSEL is low. When the nSEL signal is high, it initializes the serial interface. The number of bits sent is an integer multiple of 8. All commands consist of a command code, followed by a varying number of parameter or data bits. All data are sent MSB first (e.g. bit 15 for a 16-bit command). Bits having no influence (don’t care) are indicated with X. The Power On Reset (POR) circuit sets default values in all control and command registers. Timing Specification Symbol Parameter Minimum value [ns] tCH Clock high time 25 tCL Clock low time 25 tSS Select setup time (nSEL falling edge to SCK rising edge) 10 tSH Select hold time (SCK falling edge to nSEL rising edge) 10 tSHI Select high time 25 tDS Data setup time (SDI transition to SCK rising edge) 5 tDH Data hold time (SCK rising edge to SDI transition) 5 tOD Data delay time 10 tBL Push-button input low time 25 Timing Diagram tSHI tSS nSEL tCH tCL tOD tSH SCK tDS SDI nIRQ tDH BIT15 BIT14 BIT13 BIT8 BIT7 POR BIT1 WK-UP BIT0 nIRQ 12 Si4020 Control Commands Control Command Related Parameters/Functions 1 Configuration Setting Command Frequency band, microcontroller clock output, crystal load capacitance, frequency deviation 2 Power Management Command Crystal oscillator, synthesizer, power amplifier, low battery detector, wake-up timer, clock output buffer 3 Frequency Setting Command Carrier frequency 4 Data Rate Command Bit rate (at EEPROM mode only) 5 Power Setting Command Nominal output power, OOK mode 6 Low Battery Detector Command Low battery threshold limit 7 Sleep Command Length of the clock tail after power down 8 Push-Button Command Push-button related functions 9 Wake-Up Timer Command Wake-up time period 10 Data Transmit Command Data transmission 11 Status Register Command Transmitter status read Note: In the following tables the POR column shows the default values of the command registers after power-on. 1. Configuration Setting Command bit 15 1 14 0 b1 0 0 1 1 13 0 12 b1 11 b0 10 d2 9 d1 b0 0 1 0 1 Frequency Band [MHz] 315 433 868 915 8 d0 7 x3 6 x2 5 x1 4 x0 x3 0 0 0 0 3 ms x2 0 0 0 0 2 m2 x1 0 0 1 1 1 m1 x0 0 1 0 1 0 m0 POR 8080h Crystal Load Capacitance [pF] 8.5 9.0 9.5 10.0 … d2 d1 d0 0 0 0 0 1 1 1 1 0 0 1 1 0 0 1 1 0 1 0 1 0 1 0 1 Clock Output Frequency [MHz] 1 1.25 1.66 2 2.5 3.33 5 10 1 1 1 1 1 1 0 1 15.5 16.0 The resulting output frequency can be calculated as: fout = f0 – (-1)SIGN * (M + 1) * (30 kHz) where: f0 is the channel center frequency (see the next command) M is the three bit binary number <m2 : m0> SIGN = (ms) XOR (FSK input) 13 Si4020 2. Power Management Command bit 15 1 14 1 13 0 12 0 11 0 10 0 9 0 8 0 7 a1 6 a0 5 ex 4 es 3 ea 2 eb 1 et 0 dc POR C000h Bits 5-0, enable the corresponding block of the transmitters, i.e. the crystal oscillator is enabled by the ex bit, the synthesizer by es, the power amplifier by ea and the low battery detector by eb, while the wake-up timer by et. The bit dc disables the clock output buffer. When receiving the Data Transmit Command, the chip supports automatic on/off control over the crystal oscillator, the PLL and the PA. If bit a1 is set, the crystal oscillator and the synthesizer are controlled automatically. Data Transmit Command starts up the crystal oscillator and as soon as a stable reference frequency is available the synthesizer starts. After a subsequent delay to allow locking of the PLL, if a0 is set the power amplifier is turned on as well. Note: • To enable the automatic internal control of the crystal oscillator, the synthesizer and the power amplifier, the corresponding bits (ex, es, ea) must be zero in the Power Management Command. • In microcontroller mode, the ex bit should be set in the Power Management Command for the correct control of es and ea. The oscillator can be switched off by clearing the ex bit after the transmission. • In EEPROM operation mode after an identified Data Transmit Command the internal logic switches on the synthesizer and PA. At the end of Data Transmit Command header if necessary the current clock cycle is automatically extended to ensure the PLL stabilization and RF power ramp-up. • In EEPROM operation mode the internal logic switches off the PA when the given number of bytes is transmitted. (See: Data Transmit Command in EEPROM operation.) • When the chip is controlled by a microcontroller, the Sleep Command can be used to indicate the end of the data transmission process, because in microcontroller mode the Data Transmit Command does not contain the length of the TX data. • For processing the events caused by the peripheral blocks (POR, LBD, wake-up timer, push-buttons) the chip requires operation of the crystal oscillator. This operation is fully controlled internally, independently from the status of the ex bit, but if the dc bit is zero, the oscillator remains active until Sleep Command is issued. (This command can be considered as an event controller reset.) Oscillator control logic 14 Si4020 3. Frequency Setting Command bit 15 1 14 0 13 1 12 0 11 f11 10 f10 9 f9 8 f8 7 f7 6 f6 5 f5 4 f4 3 f3 2 f2 1 f1 0 f0 POR A7D0h The constants C1 and C2 are determined by the selected band as: The 12-bit parameter of the Frequency Setting Command <f11 : f0> has the value F. The value F should be in the range of 96 and 3903. When F is out of range, the previous value is kept. The synthesizer center frequency f0 can be calculated as: Band [MHz] 315 433 868 915 f0 = 10 MHz * C1 * (C2 + F/4000) C1 1 1 2 3 C2 31 43 43 30 Note: • For correct operation of the frequency synthesizer, the frequency and band of operation need to be programmed before the synthesizer is started. Directly after activation of the synthesizer, the RF VCO is calibrated to ensure proper operation in the programmed frequency band. • When coding for the Si4020, it is suggested that recalibration routines be added to compensate for significant changes in temperature and supply voltages. 4. Data Rate Command bit 15 1 14 1 13 0 12 0 11 1 10 0 9 0 8 0 7 r7 6 r6 5 r5 4 r4 3 r3 2 r2 1 r1 0 r0 POR C800h In EEPROM mode the transmitted bit rate is determined by the 8-bit value R (bits <r7 : r0>) as: BR = 10 MHz / 29 / (R+1) Apart from setting custom values, the standard bit rates from 2.4 to 115.2 kbps can be approximated with minimal error. The commands are read out with a different fixed bit rate: Fsck = 10 MHz / 29 / 3 [~115.2 kHz] 5. Power Setting Command bit 7 1 6 0 5 1 4 1 3 ook 2 p2 1 p1 0 p0 POR B0h The bit ook enables the OOK mode for the PA, in this case the data to be transmitted are received through the FSK pin. p2 0 0 0 0 1 1 1 1 p1 0 0 1 1 0 0 1 1 p0 0 1 0 1 0 1 0 1 Relative Output Power [dB] 0 -3 -6 -9 -12 -15 -18 -21 The output power is given in the table as relative to the maximum available power, which depends on the actual antenna impedance. (See: Antenna Application Note available from www.silabs.com/integration). 15 Si4020 6. Low Battery Detector Command bit 15 1 14 1 13 0 12 0 11 0 10 0 9 1 8 0 7 0 6 0 5 0 4 t4 3 t3 2 t2 1 t1 0 t0 POR C200h 3 s3 2 s2 1 s1 0 s0 POR C400h The 5-bit value T of <t4 : t0> determines the threshold voltage Vlb of the detector: Vlb = 2.25 V + T * 0.1 V 7. Sleep Command bit 15 1 14 1 13 0 12 0 11 0 10 1 9 0 8 0 7 s7 6 s6 5 s5 4 s4 The effect of this command depends on the Power Management Command. It immediately disables the power amplifier (if a0=1 and ea=0) and the synthesizer (if a1=1 and es=0). Stops the crystal oscillator after S periods of the microcontroller clock (if a1=1 and ex=0) to enable the microcontroller to execute all necessary commands before entering sleep mode itself. The 8-bit value S is determined by bits <s7 : s0>. 8. Push-Button Command bit 15 1 14 1 13 0 12 0 11 1 10 0 9 1 8 0 7 p4 6 d1 5 d0 4 b4 3 b3 2 b2 1 b1 0 bc POR CA00h If the corresponding bit was set (b1-b4) the event remains active while the button is pressed. In EEPROM mode, the chip is continuously performing the routine assigned to the push-button while it is pressed. In microcontroller mode, the chip continuously generates interrupts on nIRQ until the push-button is released. Weak pull-up currents are switched off when bc is high. The d0, d1 bits set the de-bouncing time period: d1 d0 De-bouncing Time [ms] 0 0 160 0 1 40 1 0 10 1 1 0 (Bypassed) Note: • Until the de-bouncing time has expired, the crystal oscillator remains switched on, independent of the status of the ex bit in the Power Management Command. (Because the circuit uses the crystal oscillator signal for timing.) If the p4 bit is set, the controller performs the routine assigned to the fourth button when PB1 and PB2 are pressed down simultaneously. With the addition of this feature, there is a way to build a device that uses 3 buttons, but performs 4 functions. It is possible to detect multiple pressed push-buttons in both modes. In EEPROM mode the controller executes sequentially all the routines belonging to the pressed buttons. 16 Si4020 Simultaneously Pressed Push-Button Detect by Microcontroller Microcontroller mode Vdd POR (internal) Push button input 1 Push button input 2 nIRQ POR PB1 PB1 PB2 PB1 PB2 PB1 PB_nIRQdly* SPI Status rd Status rd Status rd Status rd Status rd Status rd Status rd Note: *PB_nIRQdly is equal with the debounce time Simplified Block Diagram of Push-Button 1–4 Inputs POR, LBD, WAKE UP TIMER, P. BUTTONS EVENT FLAGS VDD VDD WEAK PULL-UP ENABLE/DISABLE Push-button1,2,3 CLK Notice: Only one EVENT is serviced simultaneously the others are pending. EVENT FLAG bc D Digital glitch filter CLR for P.B1,2 Q CLR SLEEP Command * STAT. REG. READ Command ** COUNT/SINGLE Internal blocker signal to Push-button1 and Push-button2 p4 Push-button1 Push-button2 With internal weak pull-up To Digital glitch filter for Push-button4 b1, b2, b3 Note: * In EEprom mode ** In uC controlled mode Push-button4 17 Si4020 9. Wake-Up Timer Command bit 15 1 14 1 13 1 12 r4 11 r3 10 r2 9 r1 8 r0 7 m7 6 m6 5 m5 4 m4 3 m3 2 m2 1 m1 0 m0 POR E000h The wake-up time period can be calculated as: Twake-up = M * 2R [ms] , where M is defined by the <m7 : m0> digital value and R is defined by the <r4 : r0> digital value. The value of R should be in the range of 0 and 23. The maximum achievable wake-up time period can be up to 24 days. Note: • For continual operation the et bit should be cleared and set at the end of every cycle. Software reset: Sending FF00h command to the chip triggers software reset. For more details see the Reset modes section. 10. Data Transmit Command This command is not needed if the transmitters’ power management bits (ex, es, ea) are fully controlled by the microcontroller and TX data comes through the FSK pin. In EEPROM operation mode: bit 15 1 14 1 13 0 12 0 11 0 10 1 9 1 8 0 3 0 2 1 1 1 0 0 7 n7 6 n6 5 n5 4 n4 3 n3 2 n2 1 n1 0 n0 POR -- In microcontroller slave mode: bit 7 1 6 1 5 0 4 0 POR -- This command indicates that the following bitstream coming in via the serial interface is to be transmitted. In EEPROM mode, the 8bit value N of bits <n7 : n0> contains the number of data bytes to follow. Note: • If the crystal oscillator was formerly switched off (ex=0), the internal oscillator needs tsx time, to switch on. The actual value depends on the type of quartz crystal used. • If the synthesizer was formerly switched off (es=0), the internal PLL needs tsp startup time. Valid data can be transmitted only when the internal locking process is finished. • In EEPROM mode, before issuing the Data Transmit Command, the power amplifier must be enabled, with the ea or a0 bit in the Power Management Command. • In EEPROM mode, when N bytes have been read and transmitted the controller continues reading the EEPROM and processing the data as control commands. This process stops after Sleep Command has been read from the EEPROM. 18 Si4020 Data Transmit Sequence Through the FSK Pin nSEL Power Management Command C0h 38h SCK instruction SDI tsx * Internal operations a0, a1 = 0 ex, es, ea = 1 xtal osc. stable Xtal osc staus tsp * synthesizer / PLL / PA status FSK synthesizer on, PLL locked, PA ready to transmit don't care TX DATA NOTE: * See page 6 for the timing values Data Transmit Sequence Through the SDI Pin Note: • Do not send CLK pulses with the TX data bits; otherwise they will be interpreted as commands. • This mode is not SPI compatible, therefore it is not recommended in microcontroller mode. • If the crystal oscillator and the PLL are running, the tsx+tsp delay is not needed. 19 Si4020 11. Status Register Read Command bit 15 1 14 1 13 0 12 0 11 1 10 1 9 0 8 0 7 0 6 0 5 0 4 0 3 0 2 0 1 0 0 0 POR -- With this command, it is possible to read the chip’s status register through the nIRQ pin. This command clears the last serviced interrupt and processing the next pending one will start (if there is any). Status Register Read Sequence nSEL 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 SCK instruction SDI status out nIRQ POR PB1 PB2 PB3 PB4 LBD WK-UP nIRQ 20 Si4020 EEPROM MODE In this mode, the transmitters can operate with a standard at least 1 kbyte serial EEPROM with an SPI interface, and no microcontroller is necessary. The following events cause wake-up of the device: Event Number N EEPROM entry point 0 0000h power-on Description 1 0080h low level on input PB1 2 0100h low level on input PB2 3 0180h low level on input PB3 4 0200h low level on input PB4 5 0280h low supply voltage level 6 0300h wake-up timer timeout After any of these events, the crystal oscillator turns on and the device starts to read bytes from the EEPROM continuously (block read) starting from address N * 128 (decimal) and executes them as commands as described in the previous section. Note: Zero bytes can be put in the EEPROM for timing purposes. Never put more than 31 consecutive zero bytes into the EEPROM’s active region (between the actual entry point and the closing Sleep Command). Example EEPROM Hex Content Power-On Reset: 00000000 00000010 00000020 00000030 00000040 00000050 00000060 00000070 C0 00 00 00 00 00 00 00 C4 00 00 00 00 00 00 00 CA 00 00 00 00 00 00 00 1E 00 00 00 00 00 00 00 C8 00 00 00 00 00 00 00 23 00 00 00 00 00 00 00 C4 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 Short Explanation: Data in Address, Command, and Parameter fields are hexadecimal values. For the detailed description of the control command bits, see previous section. Address Command Parameter Related Control Command Remarks 00–01 C0 C4 Power Management Crystal – Synthesizer – Power Amplifier auto on/off mode enable 02–03 CA 1E Push Button Continuous execution for all push buttons 04–05 C8 23 Bit Rate BR = 10M / 29 / ( 35+1 ) ~ 9600 bps 06-07 C4 00 Sleep Power down 21 Si4020 Push-button 1: 00000080 00000090 000000A0 000000B0 000000C0 000000D0 000000E0 000000F0 88 55 55 55 55 55 55 00 72 55 55 55 55 55 55 00 A6 55 55 55 55 55 55 00 10 55 55 55 55 55 55 00 C6 55 55 55 55 55 55 00 60 55 55 55 55 55 55 00 55 55 55 55 55 55 C4 00 55 55 55 55 55 55 00 00 55 55 55 55 55 55 00 00 55 55 55 55 55 55 00 00 55 55 55 55 55 55 00 00 55 55 55 55 55 55 00 00 55 55 55 55 55 55 00 00 55 55 55 55 55 55 00 00 55 55 55 55 55 55 00 00 55 55 55 55 55 55 00 00 Short Explanation: Address Command Parameter Related Control Command Remarks 433MHz band, Xtal CL=12pF fdev=90kHz 80–81 8 872 Configuration Control 82–83 A 610 Frequency fc=(43+1552/4000)*10MHz 84–85 C6 60 Data Transmit Transmit the next 96 bytes Sleep Power down, go to address 80 (see note) 86–E5 E6–E7 60x55 C4 00 Data Note: • This routine is repeatedly executed while PB1 is pressed, because continuous execution was selected at POR (CA1E code issued in the power-on reset section before). RX-TX ALIGNMENT PROCEDURES RX-TX frequency offset can be caused only by the differences in the actual reference frequency. To minimize these errors it is suggested to use the same crystal type and the same PCB layout for the crystal placement on the RX and TX PCBs. To verify the possible RX-TX offset it is suggested to measure the CLK output of both chips with a high level of accuracy. Do not measure the output at the XTL pin since the measurement process itself will change the reference frequency. Since the carrier frequencies are derived from the reference frequency, having identical reference frequencies and nominal frequency settings at the TX and RX side there should be no offset if the CLK signals have identical frequencies. It is possible to monitor the actual RX-TX offset using the AFC status report included in the status byte of the receiver. By reading out the status byte from the receiver, the actual measured offset frequency will be reported. In order to get accurate values the AFC has to be disabled during the read by clearing the "en" bit in the AFC Control Command (bit 0). 22 Si4020 CRYSTAL SELECTION GUIDELINES The crystal oscillator of the Si4020 requires a 10 MHz parallel mode crystal. The circuit contains an integrated load capacitor in order to minimize the external component count. The internal load capacitance value is programmable from 8.5 pF to 16 pF in 0.5 pF steps. With appropriate PCB layout, the total load capacitance value can be 10 pF to 20 pF so a variety of crystal types can be used. When the total load capacitance is not more than 20 pF and a worst case 7 pF shunt capacitance (C0) value is expected for the crystal, the oscillator is able to start up with any crystal having less than 300 ohms ESR (equivalent series loss resistance). However, lower C0 and ESR values guarantee faster oscillator startup. The crystal frequency is used as the reference of the PLL, which generates the RF carrier frequency (fc). Therefore, fc is directly proportional to the crystal frequency. The accuracy requirements for production tolerance, temperature drift and aging can thus be determined from the maximum allowable carrier frequency error. Maximum XTAL Tolerances Including Temperature and Aging [ppm] Transmitter Deviation [+/- kHz] Bit Rate: 2.4kbps 30 60 90 120 150 180 210 315 MHz 30 75 100 100 100 100 100 433 MHz 20 50 75 100 100 100 100 868 MHz 10 25 40 60 75 100 100 915 MHz 10 25 40 50 75 75 100 Transmitter Deviation [+/- kHz] Bit Rate: 9.6kbps 30 60 90 120 150 180 210 315 MHz 25 70 100 100 100 100 100 433 MHz 15 50 75 100 100 100 100 868 MHz 8 25 40 60 75 75 100 915 MHz 8 25 40 50 70 75 100 Transmitter Deviation [+/- kHz] Bit Rate: 38.3kbps 30 60 90 120 150 180 210 315 MHz don’t use 30 75 100 100 100 100 433 MHz don't use 20 50 75 100 100 100 868 MHz don't use 10 30 40 60 75 100 915 MHz don't use 10 25 40 60 75 75 Whenever a low frequency error is essential for the application, it is possible to “pull” the crystal to the accurate frequency by changing the load capacitor value. The widest pulling range can be achieved if the nominal required load capacitance of the crystal is in the “midrange”, for example 16 pF. The “pull-ability” of the crystal is defined by its motional capacitance and C0. Note: There may be other requirements for the TX carrier accuracy with regards to the requirements as defined by standards and/or channel separations. 23 Si4020 RESET MODES The chip will enter into reset mode if any of the following conditions are met: • Power-on reset: During a power up sequence until the Vdd has reached the correct level and stabilized • Power glitch reset: Transients present on the Vdd line • Software reset: Special control command received by the chip Power-on reset After power up the supply voltage starts to rise from 0V. The reset block has an internal ramping voltage reference (reset-ramp signal), which is rising at 100mV/ms (typical) rate. The chip remains in reset state while the voltage difference between the actual Vdd and the internal reset-ramp signal is higher than the reset threshold voltage, which is 600 mV (typical). As long as the Vdd voltage is less than 1.6V (typical) the chip stays in reset mode regardless the voltage difference between the Vdd and the internal ramp signal. The reset event can last up to 150ms supposing that the Vdd reaches 90% its final value within 1ms. During this period the chip does not accept control commands via the serial control interface. Power-on reset example: Power glitch reset The internal reset block has two basic mode of operation: normal and sensitive reset. The default mode is sensitive, which can be changed by the appropriate control command (see Related control commands at the end of this section). In normal mode the power glitch detection circuit is disabled. There can be spikes or glitches on the Vdd line if the supply filtering is not satisfactory or the internal resistance of the power supply is too high. In such cases if the sensitive reset is enabled an (unwanted) reset will be generated if the positive going edge of the Vdd has a rising rate greater than 100mV/ms and the voltage difference between the internal ramp signal and the Vdd reaches the reset threshold voltage (600 mV). Typical case when the battery is weak and due to its increased internal resistance a sudden decrease of the current consumption (for example turning off the power amplifier) might lead to an increase in supply voltage. If for some reason the sensitive reset cannot be disabled step-by-step decrease of the current consumption (by turning off the different stages one by one) can help to avoid this problem. Any negative change in the supply voltage will not cause reset event unless the Vdd level reaches the reset threshold voltage (250mV in normal mode, 1.6V in sensitive reset mode). If the sensitive mode is disabled and the power supply turned off the Vdd must drop below 250mV in order to trigger a power-on reset event when the supply voltage is turned back on. If the decoupling capacitors keep their charges for a long time it could happen that no reset will be generated upon power-up because the power glitch detector circuit is disabled. Note that the reset event reinitializes the internal registers, so the sensitive mode will be enabled again. 24 Si4020 Sensitive Reset Enabled, Ripple on Vdd: Vdd Reset threshold voltage (600mV) Reset ramp line (100mV/ms) 1.6V time nRes output H L Sensitive reset disabled: Vdd Reset threshold voltage (600mV) Reset ramp line (100mV/ms) 250mV time nRes output H L Software reset Software reset can be issued by sending the appropriate control command (described at the end of the section) to the chip. The result of the command is the same as if power-on reset was occurred. Vdd line filtering During the reset event (caused by power-on, fast positive spike on the supply line or software reset command) it is very important to keep the Vdd line as smooth as possible. Noise or periodic disturbing signal superimposed the supply voltage may prevent the part getting out from reset state. To avoid this phenomenon use adequate filtering on the power supply line to keep the level of the disturbing signal below 10mVp-p in the DC – 50kHz range for 200ms from Vdd ramp start.. Typical example when a switch-mode regulator is used to supply the radio, switching noise may be present on the Vdd line. Follow the manufacturer’s recommendations how to decrease the ripple of the regulator IC and/or how to shift the switching frequency. Related control commands “Low Battery Detector Command” Setting bit<6> to high will change the reset mode to normal from the default sensitive. “SW Reset Command” Issuing FF00h command will trigger software reset. See the Wake-up Timer Command. 25 Si4020 SIMPLIFIED INTERNAL CONTROL AND TIMING The internal controller uses the clock generated by the crystal oscillator to sequentially process the various events and to de-bounce the push-button (PB) inputs. If the oscillator is not running, internal logic automatically turns it on temporarily and then off again. Such events are: any wake-up event (POR, PB press, wake-up timer timeout, and low supply voltage detection), PB release and status read request by the microcontroller. If two wake-up events occur in succession, the crystal oscillator stays on until the next status read (acknowledgment of the first event). Simplified Internal Control and Timing Diagrams Microcontroller mode (ec=0, ex=0) Vdd POR (inte rna l) Push-button inpu t x Debouncing Time + T s x* Osc_On (In terna l) SP I Status rd cmd nIRQ Status rd cmd Stat. b its (PO R) Stat. b its (PB x) Tsx* Tsx* Microcontroller mode with multiple event read (ec=0, ex=0) Vdd POR (inte rna l) Push-button inpu t x Osc_On (In terna l) SP I Status rd cmd nIRQ Status rd cmd Stat. b its Stat. b its (PB x) (PO R) 1us Tsx* Microcontroller mode (ec=1, ex=0) Vdd POR (inte rna l) Push-button inpu t x Osc_On (In terna l) SP I Status rd Slee p cmd Status rd Slee p cmd Tclk_tail** Tclk_tail** No te: * Tsx : Crystal oscillator st artup t im e ** Length of Tclk_tail is determined by the parameter in the Sleep comm a nd 26 Si4020 MATCHING NETWORK FOR A 50 OHM SINGLE ENDED OUTPUT Matching Network Schematic Si4020 L1 [nH] L2 [nH] L3 [nH] C1 [pF] C2 [pF] C3 [pF] 315 MHz 72 110 390 3.9 2.2 56..100 433 MHz 43 82 390 2.7 1.5 56..100 868 MHz 10 27 100 1.8 1 27..56 915 MHz 10 27 100 1.8 1 27..56 27 Si4020 EXAMPLE APPLICATIONS For Microcontroller Mode Schematic PCB Layout of Keyboard Transmitter Demo Circuit Using Microcontroller Mode (operating in the 915 MHz band) Top Layer Bottom Layer 28 Si4020 For EEPROM Mode Schematic PCB Layout of Push-Button Transmitter Demo Circuit Using EEPROM Mode (operating in the 434 MHz band) Top Layer Bottom Layer 29 Si4020 PACKAGE INFORMATION 16-pin TSSOP See Detail “A” Section B-B Gauge Plane 0.25 Detail “A” Symbol A A1 A2 b b1 c c1 D e E E1 L L1 R R1 1 2 3 Min. 0, 05 0,80 0, 19 0,19 0, 09 0, 09 4,90 4,30 0,50 Dimensions in mm Nom. Max. 1, 20 0, 15 0,90 1,05 0, 30 0,22 0,25 0, 20 0, 16 5,00 5,10 0.65 BSC. 6.40 BSC. 4,40 4,50 0,60 0,75 1.00 REF. 0 , 09 0, 09 0 8 12 REF. 12 REF. Dimensions in Inches Nom. Max. 0,047 0, 002 0, 006 0,031 0,035 0,041 0, 007 0, 012 0,007 0,009 0,010 0, 004 0, 008 0, 004 0, 006 0,193 0,197 0,201 0.026 BSC. 0.252 BSC. 0,169 0,173 0,177 0,020 0,024 0,030 0.39 REF. 0, 004 0,004 0 8 12 REF. 12 REF. Min. 30 Si4020 This page has been intentionally left blank. 31 Si4020 RELATED PRODUCTS AND DOCUMENTS Si4020 Universal ISM Band FSK Transmitter DESCRIPTION ORDERING NUMBER Si4020 16-pin TSSOP Si4020-IC CC16 die see Silicon Labs Rev I1 Demo Boards and Development Kits DESCRIPTION ORDERING NUMBER Development Kit IA ISM – DK Remote Temperature Monitoring Station IA ISM – DATD Related Resources DESCRIPTION ORDERING NUMBER Antenna Selection Guide IA ISM – AN1 Antenna Development Guide IA ISM – AN2 IA4320 Universal ISM Band FSK Receiver See www.silabs.com/integration for details Note: Volume orders must include chip revision to be accepted. Silicon Labs, Inc. 400 West Cesar Chavez Austin, Texas 78701 Tel: 512.416.8500 Fax: 512.416.9669 Toll Free: 877.444.3032 www.silabs.com/integration [email protected] The specifications and descriptions in this document are based on information available at the time of publication and are subject to change without notice. Silicon Laboratories assumes no responsibility for errors or omissions, and disclaims responsibility for any consequences resulting from the use of information included herein. Additionally, Silicon Laboratories assumes no responsibility for the functioning of undescribed features or parameters. Silicon Laboratories reserves the right to make changes to the product and its documentation at any time. Silicon Laboratories makes no representations, warranties, or guarantees regarding the suitability of its products for any particular purpose and does not assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability for consequential or incidental damages arising out of use or failure of the product. Nothing in this document shall operate as an express or implied license or indemnity under the intellectual property rights of Silicon Laboratories or third parties. The products described in this document are not intended for use in implantation or other direct life support applications where malfunction may result in the direct physical harm or injury to persons. NO WARRANTIES OF ANY KIND, INCLUDING BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, ARE OFFERED IN THIS DOCUMENT. ©2008 Silicon Laboratories, Inc. All rights reserved. Silicon Laboratories is a trademark of Silicon Laboratories, Inc. All other trademarks belong to their respective owners. 32