TXE-315-KH2

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DESCRIPTION

The KH2 Series is ideally suited for volume use in OEM applications such as remote control and command, and keyless entry. Housed in a compact SMD package, it combines a highly- optimized RF transmitter with an on-board encoder. When paired with a matching KH2 Series receiver / decoder module, a reliable wireless link is formed, capable of transferring the status of 8 parallel inputs over distances of up to 3,000 feet. Ten tri-state address lines provide 59,049 (3 10) addresses for security and uniqueness. No external RF components are required except an antenna, making integration straightforward. KH2 SERIES TRANSMITTER / ENCODER DATA GUIDE WIRELESS MADE SIMPLE® Revised 9/27/11 Figure 1: Package Dimensions 0.180" 0.630" 1.220" LOT 10000 RF TRANSMITTER/ENCODER TXE-418-KH2 nRemote Control / Command nKeyless Entry nGarage / Gate Openers nLighting Control nCall Systems nHome / Industrial Automation nFire / Security Alarms nRemote Status Monitoring nWire Elimination APPLICATIONS INCLUDE nLow cost nOn-board encoder n8 parallel binary inputs n310addresses for security and uniqueness nNo external RF components required nUltra-low power consumption nCompact SMD package nStable SAW-based architecture nAdjustable output power nTransmit enable line nNo production tuning

FEATURES

PART # DESCRIPTION TXE-315-KH2 Transmitter 315MHz TXE-418-KH2 Transmitter 418MHz TXE-433-KH2 Transmitter 433MHz RXD-315-KH2 Receiver 315MHz RXD-418-KH2 Receiver 418MHz RXD-433-KH2 Receiver 433MHz EVAL-*-KH2 Basic Evaluation Kit * = 315, 418 (Standard), 433.92MHz. Transmitters are supplied in tubes of 20 pcs.

ORDERING INFORMATION

Figure 6: KH2 Series Transmitter Pinout (Top View) Pin #Name Description 1GND / LADJ Level Adjust. This line can be used to adjust the output power level of the transmitter. Connecting to GND will give the highest output, while placing a resistor to GND will lower the output level. 2, 3, 7-12D0 - D1 Data Input Lines. When TE goes high, the module will encode the state of these lines for transmission. Upon receipt of a valid transmission, the receiver / decoder will replicate these lines on its output lines. 4GND Analog Ground

5 VCCSupply Voltage

Transmit Enable Line. When this line goes high, the module will encode the states of the address and data lines into a packet and transmit the packet three times. 13-22A0-A9 Address Lines. The state of these lines must match the state of the receiver’s address lines in order for a transmission to be accepted. 23GND Analog Ground

24 ANT50-ohm RF Output

The KH2 Series transmitter / encoder module combines a high-performance Surface Acoustic Wave (SAW) based transmitter with an on-board encoder. When combined with a Linx KH2 Series receiver / decoder, a highly reliable RF link capable of transferring control or command data over line-of-sight distances of up to 3,000 feet is formed. The module accepts up to 8 parallel inputs, such as switches or contact closures, and provides ten tri-state address lines for security and creation of 59,049 (3 10) unique transmitter / receiver relationships. The KH’s compact surface-mount package integrates easily into existing designs and is friendly to hand production or automated assembly. THEORY OF OPERATION The KH2 Series transmitter operation is straightforward. When the Transmit Enable (TE) line is taken high, the on-board encoder IC is activated. The encoder detects the logic states of the data and address lines. These states are formatted into a 3-word transmission, which continues until the TE line is taken low. The encoder creates a serial data packet that is used to modulate the transmitter. The transmitter section is based on a simple, but highly-optimized, architecture that achieves a high fundamental output power with low harmonic content. This ensures that most approval standards can be met without external filter components. The KH2 Series transmitter is exceptionally stable over variations in time, temperature, and physical shock as a result of the precision SAW device that is incorporated as the frequency reference. The transmitted signal may be received by a Linx KH2 Series receiver / decoder module or a Linx LR Series receiver combined with the appropriate decoder IC. Once data is received, it is decoded using a decoder IC or custom microcontroller. The transmitted address bits are checked against the address settings of the receiving device. If a match is confirmed, the decoder’s outputs are set to replicate the transmitter’s inputs. Output Isolation & Filter RF Amplifier TRI-Detect Buffer Sync GATE Counter Divider TX Enable Keyed Output SAW Oscillator 50Ω RF OUT (ANT)OSC Parallel Inputs D0-D7 Address Inputs A0-A9 RF STAGE ENCODER STAGE Figure 7: KH2 Series Transmitter Block Diagram

The module does not have an internal voltage regulator; therefore it requires a clean, well-regulated power source. While it is preferable to power the unit from a battery, it can also be operated from a power supply as long as noise is less than 20mV. Power supply noise can affect the transmitter modulation; therefore, providing a clean power supply for the module should be a high priority during design. A 10Ωresistor in series with the supply followed by a 10µF tantalum capacitor from V CCto ground will help in cases where the quality of supply power is poor. These values may need to be adjusted depending on the noise present on the supply line. DATA INPUTS When the Transmit Enable (TE) line goes high, the states of the eight data input lines are recorded and encoded for transmission. The data lines are tri-state, which means that they can be high, low, or floating, though the decoder will interpret the floating state as a low. This feature means that the data lines do not require pull-up or pull-down resistors. The states of the data lines can be set by switches, jumpers, microcontrollers, or hardwired on the PCB. The encoder will send the states of the address and data lines three times. If the TE line is still high, it will begin the cycle again. This means that the states of the data lines are refreshed with each cycle, so the data lines can be changed without having to pull TE low. There can be up to a 150mS lag in response as the transmitter finishes one cycle then refreshes and starts over. ENABLING TRANSMISSION The module’s Transmit Enable (TE) line controls transmission status. When taken high, the module initiates transmission, which continues until the line is pulled low or power to the module is removed. In some cases this line will be wired permanently to V CCand transmission controlled by switching VCCto the module. This is particularly useful in applications where the module powers up and sends a transmission only when a button is pressed on the remote. USING LADJ The LADJ line allows the transmitter’s output power to be easily adjusted for range control, lower power consumption, or to meet legal requirements. This is done by placing a resistor between GND and LADJ. When LADJ is connected directly to GND, the output power will be at its maximum. Placing a resistor will lower the output power by up to 7dB, as shown on Page 3 of this data guide. This is very useful during FCC testing to compensate for antenna gain or other product-specific issues that may cause the output power to exceed legal limits. A variable resistor can be used so that the test lab can precicely adjust the output power to the maximun level allowed by law. The resistor’s value can be noted and a fixed resistor substituted for final testing. Even in designs where attenuation is not anticipated, it is a good idea to place a resistor pad connected to LADJ and GND so that it can be used if needed. 10Ω 10μF Vcc IN Vcc TO MODULE Figure 10: Supply Filter ENCODER OPERATION The KH2 Series transmitter internally utilizes the HT640 encoder from Holtek. The encoder begins a three-word transmission cycle when the Transmission Enable line (TE) is pulled high. This cycle will repeat itself for as long as the TE line is held high. Once TE falls low, the encoder output completes its final cycle and then stops as shown in the Encoder / Decoder Timing diagram. When a transmission enable signal is applied, the encoder scans and transmits the status of the 10 bits of the address code and the 8 bits of the data serially in the order A0 to A9, D0 to D7. The status of each address / data pin can be individually preset to logic high, low, or floating. The floating state on the data input is interpreted as logic low by the decoders since the decoder output only has two states. The address pins are usually set to transmit particular security codes by DIP switches or PCB wiring, while the data is selected using push buttons or electronic switches. The floating state allows the KH2 transmitter to be used without pull- up or pull-down resistors on the data and address input lines. SETTING THE TRANSMITTER ADDRESS The module provides ten tri-state address lines. This allows for the formation of up to 59,049 (310) unique transmitter-receiver relationships. Tri-state means that the address lines have three distinct states: high, low, or floating. These pins may be hardwired or configured via a microprocessor, DIP switch, or jumpers. The receiver’s address line states must match the transmitter’s exactly for a transmission to be recognized. If the transmitted address does not match the receiver’s local address, then the receiver will take no action. Power On Standby Mode Transmission Enabled? Yes No

3 Data Words

Still Enabled? Figure 8: Encoder Flowchart CheckCheck < 1 Word

3 Words Transmitted Continuously 3 Words

2 Words

214 Clocks214 Clocks

Figure 9: Encoder / Decoder Timing Diagram

Below is an example of a basic remote control transmitter utilizing the KH2 Series transmitter. When a key is pressed on the transmitter, a corresponding line on the receiver goes high. A schematic for the receiver / decoder circuit may be found in the KH2 Series Receiver Data Guide. These circuits are implemented in the KH2 Series Basic Evaluation kit. They can be easily modified for custom applications and clearly demonstrate the ease of using the KH2 Series modules for remote control applications. The ten-position DIP switch is used to set the address to either ground or floating. Since the floating state is a valid state, no pull-up resistors are needed. The data lines are pulled high by momentary pushbuttons. Since the floating state is interpreted as a low by the decoder, no pull-down resistors are needed. Diodes are used to pull the TE line high when any data line goes high, while isolating the data lines from each other. This will make the transmitter send data when any button is pressed without affecting any of the other data lines. The KH2 Series transmitter / encoder module is also suitable for use with the Linx OEM function receivers. These receivers are FCC certified, making product introduction extremely quick. Information on these products can be found on the Linx website at www.linxtechnologies.com. CR2032 3V LITHIUM VCC 10 11 SW-DIP-10 GND GND GND VCC GND GND/LADJ1 D0 2 D1 3 GND4 VCC5 TE 6 D2 7 D3 8 D4 9 D5 10 D6 11 D7 12A013 A114 A215 A316 A417 A518 A619 A720 A821 A922 GND23 ANT24 TXE-xxx-KH2 VCC GND 100KGND

0 OHM

+C1 10uF GND VCC SW0 SW-SPDT VCC SW1 SW-SPDT VCC Figure 11: Basic Remote Control Transmitter PROTOCOL GUIDELINES While many RF solutions impose data formatting and balancing requirements, Linx RF modules do not encode or packetize the signal content in any manner. The received signal will be affected by such factors as noise, edge jitter, and interference, but it is not purposefully manipulated or altered by the modules. This gives the designer tremendous flexibility for protocol design and interface. Despite this transparency and ease of use, it must be recognized that there are distinct differences between a wired and a wireless environment. Issues such as interference and contention must be understood and allowed for in the design process. To learn more about protocol considerations, we suggest you read Linx Application Note AN-00160. Errors from interference or changing signal conditions can cause corruption of the data packet, so it is generally wise to structure the data being sent into small packets. This allows errors to be managed without affecting large amounts of data. A simple checksum or CRC could be used for basic error detection. Once an error is detected, the protocol designer may wish to simply discard the corrupt data or implement a more sophisticated scheme to correct it. INTERFERENCE CONSIDERATIONS The RF spectrum is crowded and the potential for conflict with other unwanted sources of RF is very real. While all RF products are at risk from interference, its effects can be minimized by better understanding its characteristics. Interference may come from internal or external sources. The first step is to eliminate interference from noise sources on the board. This means paying careful attention to layout, grounding, filtering, and bypassing in order to eliminate all radiated and conducted interference paths. For many products, this is straightforward; however, products containing components such as switching power supplies, motors, crystals, and other potential sources of noise must be approached with care. Comparing your own design with a Linx evaluation board can help to determine if and at what level design-specific interference is present. External interference can manifest itself in a variety of ways. Low-level interference will produce noise and hashing on the output and reduce the link’s overall range. High-level interference is caused by nearby products sharing the same frequency or from near-band high-power devices. It can even come from your own products if more than one transmitter is active in the same area. It is important to remember that only one transmitter at a time can occupy a frequency, regardless of the coding of the transmitted signal. This type of interference is less common than those mentioned previously, but in severe cases it can prevent all useful function of the affected device. Although technically it is not interference, multipath is also a factor to be understood. Multipath is a term used to refer to the signal cancellation effects that occur when RF waves arrive at the receiver in different phase relationships. This effect is a particularly significant factor in interior environments where objects provide many different signal reflection paths. Multipath cancellation results in lowered signal levels at the receiver and, thus, shorter useful distances for the link.

A whip-style antenna provides outstanding overall performance and stability. A low-cost whip is can be easily fabricated from a wire or rod, but most designers opt for the consistent performance and cosmetic appeal of a professionally-made model. To meet this need, Linx offers a wide variety of straight and reduced-height whip-style antennas in permanent and connectorized mounting styles. The wavelength of the operational frequency determines an antenna’s overall length. Since a full wavelength is often quite long, a partial 1/2- or 1/4-wave antenna is normally employed. Its size and natural radiation resistance make it well matched to Linx modules. The proper length for a straight 1/4-wave can be easily determined using the adjacent formula. It is also possible to reduce the overall height of the antenna by using a helical winding. This reduces the antenna’s bandwidth, but is a great way to minimize the antenna’s physical size for compact applications. This also means that the physical appearance is not always an indicator of the antenna’s frequency. Linx offers a wide variety of specialized antenna styles. Many of these styles utilize helical elements to reduce the overall antenna size while maintaining reasonable performance. A helical antenna’s bandwidth is often quite narrow and the antenna can detune in proximity to other objects, so care must be exercised in layout and placement. Whip Style Loop Style L =234 FMHz Where:L = length in feet ofquarter-wave length F = operating frequencyin megahertz Specialty Styles A loop- or trace-style antenna is normally printed directly on a product’s PCB. This makes it the most cost-effective of antenna styles. The element can be made self-resonant or externally resonated with discrete components, but its actual layout is usually product specific. Despite the cost advantages, loop-style antennas are generally inefficient and useful only for short-range applications. They are also very sensitive to changes in layout and PCB dielectric, which can cause consistency issues during production. In addition, printed styles are difficult to engineer, requiring the use of expensive equipment, including a network analyzer. An improperly designed loop will have a high SWR at the desired frequency, which can cause instability in the RF stage. Linx offers low-cost planar and chip antennas that mount directly to a product’s PCB. These tiny antennas do not require testing and provide excellent performance in light of their small size. They offer a preferable alternative to the often-problematic “printed” antenna. COMMON ANTENNA STYLES There are literally hundreds of antenna styles and variations that can be employed with Linx RF modules. Following is a brief discussion of the styles most commonly utilized. Additional antenna information can be found in Linx Application Notes AN-00100, AN-00140, and AN-00500. Linx antennas and connectors offer outstanding performance at a low price. ONLINE RESOURCES  Latest News  Data Guides  Application Notes  Knowledgebase  Software Updates If you have questions regarding any Linx product and have Internet access, make www.linxtechnologies.com your first stop. Our website is organized in an intuitive format to immediately give you the answers you need. Day or night, the Linx website gives you instant access to the latest information regarding the products and services of Linx. It’s all here: manual and software updates, application notes, a comprehensive knowledgebase, FCC information, and much more. Be sure to visit often! www.antennafactor.com The Antenna Factor division of Linx offers a diverse array of antenna styles, many of which are optimized for use with our RF modules. From innovative embeddable antennas to low-cost whips, domes to Yagis, and even GPS, Antenna Factor likely has an antenna for you, or can design one to meet your requirements. www.connectorcity.com Through its Connector City division, Linx offers a wide selection of high-quality RF connectors, including FCC- compliant types such as RP-SMAs that are an ideal match for our modules and antennas. Connector City focuses on high-volume OEM requirements, which allows standard and custom RF connectors to be offered at a remarkably low cost. T www.linxtechnologies.com

When working with RF, a clear distinction must be made between what is technically possible and what is legally acceptable in the country where operation is intended. Many manufacturers have avoided incorporating RF into their products as a result of uncertainty and even fear of the approval and certification process. Here at Linx, our desire is not only to expedite the design process, but also to assist you in achieving a clear idea of what is involved in obtaining the necessary approvals to legally market your completed product. In the United States, the approval process is actually quite straightforward. The regulations governing RF devices and the enforcement of them are the responsibility of the Federal Communications Commission (FCC). The regulations are contained in Title 47 of the Code of Federal Regulations (CFR). Title 47 is made up of numerous volumes; however, all regulations applicable to this module are contained in Volume 0-19. It is strongly recommended that a copy be obtained from the Government Printing Office in Washington or from your local government bookstore. Excerpts of applicable sections are included with Linx evaluation kits or may be obtained from the Linx Technologies website, www.linxtechnologies.com. In brief, these rules require that any device that intentionally radiates RF energy be approved, that is, tested for compliance and issued a unique identification number. This is a relatively painless process. Linx offers full EMC pre- compliance testing in our HP / Emco-equipped test center. Final compliance testing is then performed by one of the many independent testing laboratories across the country. Many labs can also provide other certifications that the product may require at the same time, such as UL, CLASS A / B, etc. Once your completed product has passed, you will be issued an ID number that is to be clearly placed on each product manufactured. Questions regarding interpretations of the Part 2 and Part 15 rules or measurement procedures used to test intentional radiators, such as Linx RF modules, for compliance with the technical standards of Part 15, should be addressed to: Federal Communications Commission Equipment Authorization Division Customer Service Branch, MS 1300F2

7435 Oakland Mills Road

Columbia, MD 21046 Phone: (301) 725-1585 Fax: (301) 344-2050 E-Mail: labinfo@fcc.gov International approvals are slightly more complex, although Linx modules are designed to allow all international standards to be met. If you are considering the export of your product abroad, you should contact Linx Technologies to determine the specific suitability of the module to your application. All Linx modules are designed with the approval process in mind and thus much of the frustration that is typically experienced with a discrete design is eliminated. Approval is still dependent on many factors, such as the choice of antennas, correct use of the frequency selected, and physical packaging. While some extra cost and design effort are required to address these issues, the additional usefulness and profitability added to a product by RF makes the effort more than worthwhile. NOTE:Linx RF modules are designed as component devices that require external components to function. The modules are intended to allow for full Part 15 compliance; however, they are not approved by the FCC or any other agency worldwide. The purchaser understands that approvals may be required prior to the sale or operation of the device, and agrees to utilize the component in keeping with all laws governing its use in the country of operation. ACHIEVING A SUCCESSFUL RF IMPLEMENTATION Adding an RF stage brings an exciting new dimension to any product. It also means that additional effort and commitment will be needed to bring the product successfully to market. By utilizing premade RF modules, such as the LR Series, the design and approval process is greatly simplified. It is still important, however, to have an objective view of the steps necessary to ensure a successful RF integration. Since the capabilities of each customer vary widely, it is difficult to recommend one particular design path, but most projects follow steps similar to those shown at the right. In reviewing this sample design path, you may notice that Linx offers a variety of services (such as antenna design and FCC prequalification) that are unusual for a high-volume component manufacturer. These services, along with an exceptional level of technical support, are offered because we recognize that RF is a complex science requiring the highest caliber of products and support. “Wireless Made Simple” is more than just a motto, it’s our commitment. By choosing Linx as your RF partner and taking advantage of the resources we offer, you will not only survive implementing RF, you may even find the process enjoyable. HELPFUL APPLICATION NOTES FROM LINX It is not the intention of this manual to address in depth many of the issues that should be considered to ensure that the modules function correctly and deliver the maximum possible performance. As you proceed with your design, you may wish to obtain one or more of the following application notes, which address in depth key areas of RF design and application of Linx products. These applications notes are available online at www.linxtechnologies.com or by contacting the Linx literature department. DECIDE TO UTILIZE RF RESEARCH RF OPTIONS CHOOSE LINX MODULE ORDER EVALUATION KIT(S) TEST MODULE(S) WITH BASIC HOOKUP INTERFACE TO CHOSEN CIRCUIT AND DEBUG CONSULT LINX REGARDING ANTENNA OPTIONS AND DESIGN LAY OUT BOARD SEND PRODUCTION-READY PROTOTYPE TO LINX FOR EMC PRESCREENING OPTIMIZE USING RF SUMMARY GENERATED BY LINX SEND TO PART 15 TEST FACILITY RECEIVE FCC ID # COMMENCE SELLING PRODUCT Typical Steps For Implementing RF AN-00100 RF 101: Information for the RF Challenged AN-00125 Considerations For Operation Within The 260-470MHz Band AN-00130 Modulation Techniques For Low-Cost RF Data Links AN-00140 The FCC Road: Part 15 From Concept To Approval AN-00150 Use and Design of T-Attenuation Pads AN-00160 Considerations For Sending Data Over a Wireless Link AN-00300 Addressing Linx OEM Products AN-00500 Antennas: Design, Application, Performance NOTE APPLICATION NOTE TITLE

LINX TECHNOLOGIES, INC.

159 ORT LANE

MERLIN, OR 97532 PHONE: (541) 471-6256 FAX: (541) 471-6251 www.linxtechnologies.com U.S. CORPORATE HEADQUARTERS WIRELESS MADE SIMPLE® Linx Technologies is continually striving to improve the quality and function of its products. For this reason, we reserve the right to make changes to our products without notice. The information contained in this Data Guide is believed to be accurate as of the time of publication. Specifications are based on representative lot samples. Values may vary from lot-to-lot and are not guaranteed. "Typical" parameters can and do vary over lots and application. Linx Technologies makes no guarantee, warranty, or representation regarding the suitability of any product for use in any specific application. It is the customer's responsibility to verify the suitability of the part for the intended application. NO LINX PRODUCT IS INTENDED FOR USE IN ANY APPLICATION WHERE THE SAFETY OF LIFE OR PROPERTY IS AT RISK. Linx Technologies DISCLAIMS ALL WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL LINX TECHNOLOGIES BE LIABLE FOR ANY OF CUSTOMER'S INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING IN ANY WAY FROM ANY DEFECTIVE OR NON-CONFORMING PRODUCTS OR FOR ANY OTHER BREACH OF CONTRACT BY LINX TECHNOLOGIES. The limitations on Linx Technologies' liability are applicable to any and all claims or theories of recovery asserted by Customer, including, without limitation, breach of contract, breach of warranty, strict liability, or negligence. Customer assumes all liability (including, without limitation, liability for injury to person or property, economic loss, or business interruption) for all claims, including claims from third parties, arising from the use of the Products. The Customer will indemnify, defend, protect, and hold harmless Linx Technologies and its officers, employees, subsidiaries, affiliates, distributors, and representatives from and against all claims, damages, actions, suits, proceedings, demands, assessments, adjustments, costs, and expenses incurred by Linx Technologies as a result of or arising from any Products sold by Linx Technologies to Customer. Under no conditions will Linx Technologies be responsible for losses arising from the use or failure of the device in any application, other than the repair, replacement, or refund limited to the original product purchase price. Devices described in this publication may contain proprietary, patented, or copyrighted techniques, components, or materials. Under no circumstances shall any user be conveyed any license or right to the use or ownership of such items. Disclaimer © 2009 by Linx Technologies, Inc. The stylized Linx logo, Linx, “Wireless Made Simple”, CipherLinx, and the stylized CL logo are the trademarks of Linx Technologies, Inc. Printed in U.S.A.