Typical ApplicationsOrdering InformationFeaturesDescriptionDocument ControlRevision HistoryPin Out DiagramPin DescriptionMechanical DrawingAbsolute Maximum RatingsDetailed Electrical SpecificationsTheory of OperationOOK ModulationDESIGN HINT “Using the RCT-XXX-AS with a microconSAW stabilized oscillatorTROUBLESHOOTING HINT:Data RateTROUBLESHOOTING HINT:Power SupplyAntenna OutputDESIGN HINT “Antenna traces”:DESIGN HINT “Harmonic Filter”:Contact InformationTechnical Support Policy- i - RCT-XXX-ASLow-Cost SAW-stabilized surface mountOOK RF transmitter Embedding the wireless future.. Features Typical Applications Description (shown actual size) Ordering Information • Remote Keyless Entry (RKE) • Remote Lighting Controls • On-Site Paging • Asset Tracking • Wireless Alarm and Security Systems • Long Range RFID • Automated Resource Management • 315/418/433.92 MHz versions • Low Cost • .5-12V operation • 5mA current consumption at 3V • Small size: .30” x .4” • 0dBm output power at 3V • 4800 baud operation The RCT-433-AS is ideal for remote control applications where low cost and longer range are required. The transmitter operates from a 1.5-12V supply, making it ideal for battery-powered applications. The transmitter employs a SAW-stabilized oscillator, ensuring accurate frequency control for best range performance. Output power and harmonic emissions are easy to control, making FCC and ETSI compliance easy. The manufacturing-friendly SMT style package and low-cost make the RCT-433-AS suitable for high volume applications. Frequency Part Number 315 MHz RCT-315-AS 418 MHz RCT-418-AS 433.92 MHz RCT-433-AS Domestic and international orders: Mouser Electronics 1-800-346-6873 (http://www.mouser.com) Canadian orders: Haltronics Ltd. 1-800-387-7969 (http://www.haltronicsltd.com/) For a Radiotronix Representative in your area please visit www.radiotronix.com and visit our corporate information page.Document Control Created By Steve Montgomery 05/21/02 Engineering Review Tom Marks 8/21/03 Marketing Review Bryan Montgomery 8/21/03 Approved - Engineering Tom Marks 8/21/03 Approved - Marketing Bryan Montgomery 8/21/03 Revision History Revision Author Date Description 1.1.0 SJM 05/21/02 Document Created 1.2.0 BFA 07/30/03 Revision 1.3.0 SJM 8/21/03 Revision. Added troubleshooting and design tips. - ii -RCT-XXX-AS Low-Cost SAW-stabilized surface mount OOK RF transmitter © 2001,2002,2003 All Rights Reserved Pin Out Diagram Pin Description Pin No. Pin Name Description 1 ANT 50 ohm antenna output. The antenna port impedance affects output power and harmonic emissions. An L-C low-pass filter may be needed to sufficiently filter harmonic emissions. 2 GND Transmitter ground. Connect to ground plane. 3 DATA Digital data input. This input is CMOS compatible and should be driven with CMOS level inputs. 4 VCC Pin 4 provides operating voltage for the transmitter. VCC should be bypassed with a .01uF ceramic capacitor and filtered with a 4.7uF tantalum capacitor. Noise on the power supply will degrade transmitter noise performance. Mechanical Drawing 0.30” Figure 1: Mechanical Drawing of RCT-XXX-AS Figure 2: Suggested Pad Layout Absolute Maximum Ratings Parameter Min Max Units Power Supply and All Input Pins -0.3 +15 VDC Storage Temperature -50 100 °C Soldering Temperature (10sec)1 NA 350 °C NOTES 1) Hand Solder Only. The Transmitter is not suitable for IR reflow or hot air soldering. - 2 - 8/21/2003RCT-XXX-AS Low-Cost SAW-stabilized surface mount OOK RF transmitter © 2001,2002,2003 All Rights Reserved Detailed Electrical Specifications Parameter (General) Symbol Min Typ. Max Units Notes Operating Voltage Vcc 1.5 3.0 12 Volts DC Operating Current DATA=VCC Icc --- 4.5 --- mA @3V Operating Current DATA=GND Icc --- 100 --- uA @3V Frequency Accuracy TOLfc -75 0 +75 Khz @3V Center Frequency Fc --- 315.0 418.0 433.92 --- MHz RCT-315-AS RCT-418-AS RCT-433-AS Output Power --- 0 dBm @3V Baud Rate – NRZ DC --- 4800 BPS Theory of Operation OOK Modulation OOK modulation is a binary form of amplitude modulation. When a logical 0 (data line low) is being sent, the transmitter is off, fully suppressing the carrier. In this state, the transmitter current is very low, less than 1mA. When a logical 1 is being sent, the carrier is fully on. In this state, the module current consumption is at its highest, about 4.5mA with a 3V power supply. OOK is the modulation method of choice for remote control applications where power consumption and cost are the primary factors. Because OOK transmitters draw no power when they transmit a 0, they exhibit significantly better power consumption than FSK transmitters. OOK data rate is limited by the start-up time of the oscillator. High-Q oscillators which have very stable center frequencies take longer to start-up than low-Q oscillators. The start-up time of the oscillator determines the maximum data rate that the transmitter can send. DESIGN HINT “Using the RCT-XXX-AS with a microcontroller UART”: Data should be inverted when using the transmitter with a UART. The normal marking state of a UART is a logic 1, which will cause constant transmission. By inverting the data, the transmitter will be off in a marking state and on in a spacing state (logical 0), ensuring that the transmitter is on only when data is being sent. The output of the receiver would also need to be inverted to properly recover data. SAW stabilized oscillator The transmitter is basically a negative resistance LC oscillator whose center frequency is tightly controlled by a SAW resonator. SAW (Surface Acoustic Wave) resonators are fundamental frequency devices that resonate at frequencies much higher than crystals. - 3 - 8/21/2003RCT-XXX-AS Low-Cost SAW-stabilized surface mount OOK RF transmitter © 2001,2002,2003 All Rights Reserved The output of the oscillator is derived directly from the collector of the oscillator transistor. It is, therefore, very sensitive to VSWR. The module is designed to work with a 50 ohm load, which exhibits a VSWR of 1. The designer must ensure that the antenna exhibits no more than a VSWR of 2 to guarantee operation. This is particularly true for PCB trace antennas. If the module does not appear to have any output