LR Series Receiver Module Data Guide

Table of Contents !! Warning: Some customers may want Linx radio frequency (“RF”) products to control machinery or devices remotely, including machinery or devices that can cause death, bodily injuries, and/or property 1 Description damage if improperly or inadvertently triggered, particularly in industrial settings or other applications implicating life-safety concerns (“Life and 1 Features Property Safety Situations”). 1 Applications NO OEM LINX REMOTE CONTROL OR FUNCTION MODULE 2 Ordering Information SHOULD EVER BE USED IN LIFE AND PROPERTY SAFETY 2 Absolute Maximum Ratings SITUATIONS. No OEM Linx Remote Control or Function Module should be modified for Life and Property Safety Situations. Such 3 Electrical Specifications modification cannot provide sufficient safety and will void the product’s 5 Typical Performance Graphs regulatory certification and warranty. 7 Pin Assignments Customers may use our (non-Function) Modules, Antenna and 7 Pin Descriptions Connectors as part of other systems in Life Safety Situations, but 8 Module Description only with necessary and industry appropriate redundancies and in compliance with applicable safety standards, including without 9 Theory of Operation limitation, ANSI and NFPA standards. It is solely the responsibility 10 Using the RSSI Pin of any Linx customer who uses one or more of these products to incorporate appropriate redundancies and safety standards for the Life 11 The Data Output and Property Safety Situation application. 12 Using the PDN Line 13 Power Supply Requirements Do not use this or any Linx product to trigger an action directly from the data line or RSSI lines without a protocol or encoder/ 13 ESD Concerns decoder to validate the data. Without validation, any signal from 14 Typical Applications another unrelated transmitter in the environment received by the module could inadvertently trigger the action. 15 Transferring Data 16 Antenna Considerations All RF products are susceptible to RF interference that can prevent communication. RF products without frequency agility or hopping 17 Helpful Application Notes from Linx implemented are more subject to interference. This module does not 17 Protocol Guidelines have a frequency hopping protocol built in. 18 Interference Considerations Do not use any Linx product over the limits in this data guide. 19 Pad Layout Excessive voltage or extended operation at the maximum voltage could 19 Board Layout Guidelines cause product failure. Exceeding the reflow temperature profile could cause product failure which is not immediately evident. 21 Microstrip Details 22 Production Guidelines Do not make any physical or electrical modifications to any Linx product. This will void the warranty and regulatory and UL certifications 22 Hand Assembly and may cause product failure which is not immediately evident. 22 Automated Assembly 24 General Antenna Rules

26 Common Antenna Styles 28 Regulatory Considerations LR Series Receiver Module 30 Notes Data Guide Description 0.812 in (20.6mm) The LR Receiver is ideal for the wireless transfer of serial data, control, or command information in 0.630 in the favorable 260 to 470MHz band. The receiver’s (16mm) RXM-315-LR advanced synthesized architecture achieves an LOT RRxxxx outstanding typical sensitivity of –112dBm, which 0.125 in provides a 5 to 10 times improvement in range over (3.12 mm) previous solutions. When paired with a compatible Linx transmitter, a reliable wireless link is formed Figure 1: Package Dimensions capable of transferring serial data at rates of up to 10,000bps at distances of up to 1.5 miles (2,500m). This range may be reduced depending on the regulations in the country of operation. Applications operating over shorter distances or at lower data rates also benefit from increased link reliability and superior noise immunity. Housed in a tiny reflow-compatible SMD package, no external RF components are required (except an antenna), allowing for easy integration, even for engineers without previous RF experience. Features • Long range • Low power consumption • Low cost • Low supply voltage (2.1 to • PLL-synthesized architecture 3.6VDC) • Direct serial interface • Compact surface-mount package • Data rates up to 10,000bps • Wide temperature range • No external RF components • RSSI and Power-down function required • No production tuning Applications • Remote control • Periodic data transfer • Keyless entry • Home/industrial automation • Garage/gate openers • Fire/security alarms • Lighting control • Remote status/position sensing • Medical monitoring/call systems • Long-range RFID • Remote industrial monitoring • Wire elimination – 1 – Revised 3/18/2015

Ordering Information Electrical Specifications Ordering Information LR Series Receiver Specifications Part Number Description Parameter Symbol Min. Typ. Max. Units Notes TXM-315-LR 315MHz Transmitter Power Supply TXM-418-LR 418MHz Transmitter Operating Voltage V 2.7 3.0 3.6 VDC CC TXM-433-LR 433MHz Transmitter With Dropping Resistor 4.3 5.0 5.2 VDC 1,5 RXM-315-LR 315MHz Receiver Supply Current l 4.0 5.2 7.0 mA CC RXM-418-LR 418MHz Receiver Power Down Current l 20.0 28.0 35.0 µA 5 PDN RXM-433-LR 433MHz Receiver Receiver Section EVAL-***-LR LR Series Basic Evaluation Kit Receive Frequency Range F C *** = 315, 418 (Standard), 433MHz RXM-315-LR 315 MHz Receivers are supplied in tubes of 18 pcs. RXM-418-LR 418 MHz RXM-433-LR 433.92 MHz Figure 2: Ordering Information Center Frequency Accuracy –50 +50 kHz Absolute Maximum Ratings LO Feedthrough –80 dBm 2,5 IF Frequency F 10.7 MHz 5 IF Absolute Maximum Ratings Noise Bandwidth N 280 kHz 3DB Supply Voltage V −0.3 to +3.6 VDC CC Data Rate 100 10,000 bps Supply Voltage V , Using Resistor −0.3 to +5.2 VDC CC Data Output: Any Input or Output Pin −0.3 to V + 0.3 VDC CC Logic Low V 0.0 VDC 3 OL RF Input 0 dBm Logic High V 3.0 VDC 3 OH Operating Temperature −40 to +70 ºC Power Down Input: Storage Temperature −40 to +85 ºC Logic Low V 0.4 VDC IL Soldering Temperature +260ºC for 10 seconds Logic High V V –0.4 VDC IH CC Exceeding any of the limits of this section may lead to permanent damage to the device. Receiver Sensitivity –106 –112 –118 dBm 4 Furthermore, extended operation at these maximum ratings may reduce the life of this device. RSSI / Analog Dynamic Range 80 dB 5 Figure 3: Absolute Maximum Ratings Analog Bandwidth 50 5,000 Hz 5 Gain 16 mv / 5 dB Voltage with No Carrier 1.5 V 5 Antenna Port RF Input Impedance R 50 Ω 5 IN Timing Receiver Turn-On Time Via V 3.0 7.0 10.0 ms 5,6 CC Via PDN 0.04 0.25 0.50 nS 5,6 – 2 – – 3 –

Typical Performance Graphs LR Series Receiver Specifications Continued Parameter Symbol Min. Typ. Max. Units Notes Max. Time Between 10.0 ms 5 Transitions Supply Environmental Operating Temperature –40 +70 ºC 5 Range 1. The LR can utilize a 4.3 to 5.2VDC supply provided a 330Ω resistor is placed in series with V . CC RX Data 2. Into a 50Ω load. 3. When operating from a 5V source, it is important to consider that the output will swing to well less than 5 volts as a result of the required dropping resistor. Please verify that the minimum voltage will meet the high threshold requirement of the device to which data is being sent. 4. For BER of 10–5 at 1,200bps. 5. Characterized, but not tested. 6. Time to valid data output. Figure 4: Electrical Specifications Figure 5: Turn-On Time from V CC Warning: This product incorporates numerous static-sensitive components. Always wear an ESD wrist strap and observe proper ESD handling procedures when working with this device. Failure to observe PDN this precaution may result in module damage or failure. RX Data Figure 6: Turn-On Time from PDN – 4 – – 5 –

5.40 Pin Assignments 1 NC ANT 16 5.35 2 NC GND 15 mA)5.30 3 NC NC 14 Supply Current (5.25 WitRh eDsriostpopring 45 GVCNCD NNCC 1123 5.20 6 PDN NC 11 5.15 7 RSSI NC 10 8 DATA NC 9 5.10 2.7 2.8 2.9 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 5.0 5.1 5.2 Supply Voltage (VDC) Figure 9: LR Series Receiver Pinout (Top View) Figure 7: Consumption vs. Supply Pin Descriptions Pin Descriptions Pin Number Name I/O Description RFIN > –35dBm 1 NC — No Connection 2 NC — No Connection 3 NC — No Connection No RFIN 4 GND — Analog Ground 5 V — Supply Voltage CC Power Down. Pulling this line low will place the receiver into a low-current state. The 6 PDN I module will not be able to receive a signal in this state. Received Signal Strength Indicator. This line 7 RSSI O will supply an analog voltage that is propor- tional to the strength of the received signal. Figure 8: RSSI Response Time Digital Data Output. This line will output the 8 DATA O demodulated digital data. 9 NC — No Connection 10 NC — No Connection 11 NC — No Connection 12 NC — No Connection 13 NC — No Connection 14 NC — No Connection 15 GND — Analog Ground 16 RF IN — 50Ω RF Input Figure 10: Pin Descriptions – 6 – – 7 –

Module Description Theory of Operation The LR receiver is a low-cost, high-performance synthesized AM / OOK The LR Series receiver is designed receiver, capable of receiving serial data at up to 10,000bps. Its exceptional to recover data sent by an AM Data sensitivity results in outstanding range performance. The LR’s compact or Carrier-Present Carrier-Absent surface-mount package is friendly to automated or hand production. LR (CPCA) transmitter, also referred to Series modules are capable of meeting the regulatory requirements of as CW or On-Off Keying (OOK). This Carrier many domestic and international applications. type of modulation represents a logic low '0’ by the absence of a carrier The receiver's outstanding typical sensitivity of –112dBm enables system and a logic high ‘1’ by the presence Figure 12: CPCA (AM) Modulation ranges of up to 1.5 miles (2,500m) when paired with an LR Series of a carrier. This modulation method affords numerous benefits. The two transmitter operating at full power and good antennas. Legal regulations most important are: 1) cost-effectiveness due to design simplicity and 2) in the various countries will require the transmitter output power to be higher allowable output power and thus greater range in countries (such as reduced which will reduce range. Following the legal output limit for the U.S.) that average output power measurements over time. Please refer transmitters in the United States, systems based on the LR Series can to Linx Application Note AN-00130 for a further discussion of modulation achieve ranges of up to 3,000 feet (1,000m). techniques. 50Ω RF IN (Antenna) The LR receiver utilizes an advanced single-conversion superheterodyne BanFdi lSteerlect 0˚ 1I0F. 7FMiltHezr Data Slicer architecture. Transmitted signals enter the module through a 50Ω RF - Data Out port intended for single-ended connection to an external antenna. RF LNA ∑ Limiter + signals entering the antenna are filtered and then amplified by an NMOS 90˚ RSSI/Analog cascode Low Noise Amplifier (LNA). The filtered, amplified signal is then down-converted to a 10.7MHz Intermediate Frequency (IF) by mixing it PLL VCO with a low-side Local Oscillator (LO). The LO frequency is generated by a Voltage Controlled Oscillator (VCO) locked by a Phase-Locked Loop XTAL (PLL) frequency synthesizer that utilizes a precision crystal reference. The Figure 11: LR Series Receiver Block Diagram mixer stage incorporates a pair of double-balanced mixers and a unique image rejection circuit. This circuit, along with the high IF frequency and ceramic IF filters, reduces susceptibility to interference. The IF frequency is further amplified, filtered, and demodulated to recover the baseband signal originally transmitted. The baseband signal is squared by a data slicer and output to the DATA pin. The architecture and quality of the components utilized in the LR module enable it to outperform many far more expensive receiver products. – 8 – – 9 –

Using the RSSI Pin The Data Output The receiver’s Received Signal Strength Indicator (RSSI) line outputs a The CMOS-compatible data output is normally used to drive a digital voltage that is proportional to the incoming signal strength. This line has decoder IC or a microprocessor that is performing the data decoding. It a dynamic range of 80dB (typical) and can serve a variety of functions. It does not have a large current drive capability so is intended to drive high should be noted that the RSSI levels and dynamic range will vary slightly impedance loads, such as microprocessor inputs or digital logic gates. from part to part. It is also important to remember that RSSI output indicates the strength of any in-band RF energy and not necessarily just The receiver’s output may appear to switch randomly in the absence of a that from the intended transmitter; therefore, it should be used only to transmitter. This is a result of random noise in the environment. This noise qualify the level and presence of a signal. can be handled in software by implementing a noise-tolerant protocol as described in Application Note AN-00160. If a software solution is not The RSSI output can be utilized during testing or even as a product feature appropriate, the squelch circuit in Figure 13 can be used. This circuit uses to assess interference and channel quality by looking at the RSSI level a potentiometer to set a voltage reference. If the RSSI level falls below this with all intended transmitters shut off. The RSSI output can also be used reference then a comparator turns off the DATA line and stops the random in direction-finding applications, although there are many potential perils to switching. consider in such systems. Finally, it can be used to save system power by “waking up” external circuitry when a transmission is received or crosses a This circuit is good for reducing the amount of random noise that the certain threshold. The RSSI output feature adds tremendous versatility for microcontroller must deal with, but it also reduces the sensitivity of the the creative designer. receiver since the received signal level must now be higher. This reduction in sensitivity also reduces the system range. By using a potentiometer the designer can make a compromise between noise level and range. VCC VCC R5 1M R2 R6 VCC 500k 1M U1 U1 R8 2 LMV393 6 - LMV393 10k RSSI D1 3 +- 1 5 + 7 Squelched Data + R4 C1 R1 100k 0.1µ 2M R7 DATA 2M R3 5M Figure 13: LR Series Receiver Squelch Circuit – 1 0 – – 1 1 –

Using the PDN Line Power Supply Requirements The Power Down (PDN) line can be used to power down the receiver The module does not have an internal Vcc TO without the need for an external switch. This line has an internal pull-up, so voltage regulator, therefore it requires a MODULE when it is held high or simply left floating, the module is active. clean, well-regulated power source. While it is preferable to power the unit from a 10Ω Vcc IN When the PDN line is pulled to ground, the receiver enters a low-current battery, it can also be operated from a + (<40µA) power-down mode. During this time the receiver is off and cannot power supply as long as noise is less than 10µF perform any function. It may be useful to note that the startup time coming 20mV. Power supply noise can significantly out of power-down is slightly less than when applying V . affect the receiver sensitivity, therefore; CC providing clean power to the module should Figure 14: Supply Filter The PDN line allows easy control of the receiver state from external be a high priority during design. components, like a microcontroller. By periodically activating the receiver, checking for data, then powering down, the receiver’s average current A 10Ω resistor in series with the supply followed by a 10µF tantalum consumption can be greatly reduced, saving power in battery-operated capacitor from V to ground will help in cases where the quality of the CC applications. supply power is poor. These values may need to be adjusted depending on the noise present on the supply line. Note: The voltage on the PDN line should not exceed V . When used CC with a higher voltage source, such as a 5V microcontroller, an open The module can be operated from 4.3V to 5.2V by using an external 330Ω collector line should be used or a diode placed in series with the control series resistor to prevent V from exceeding 3.6V. This resistor can replace line (anode toward the module). Either method avoids damage to the CC the 10Ω in the supply filter. While the receiver's current consumption is module by preventing 5V from being placed on the PDN line while constant and makes this possible, it is recommended to operate the allowing the line to be pulled low. receiver from a 3.0 to 3.3V supply ESD Concerns The module has basic ESD protection built in, but in cases where the antenna connection is exposed to the user it is a good idea to add additional protection. A Transient Voltage Suppressor (TVS) diode, varistor or similar component can be added to the antenna line. These should have low capacitance and be designed for use on antennas. Protection on the supply line is a good idea in designs that have a user-accessible power port. – 1 2 – – 1 3 –

Typical Applications Transferring Data Figure 15 shows a circuit using the Linx LICAL-DEC-MS001 decoder. Once a reliable RF link has been established, the challenge becomes how This chip works with the LICAL-ENC-MS001 encoder to provide simple to effectively transfer data across it. While a properly designed RF link remote control capabilities. The decoder detects the transmission from provides reliable data transfer under most conditions, there are still distinct the encoder, checks for errors, and if everything is correct, replicates the differences from a wired link that must be addressed. Since the LR Series encoder’s inputs on its outputs. This makes sending key presses very easy. modules do not incorporate internal encoding or decoding, a user has More information on the operation and features of the decoder can be tremendous flexibility in how data is handled. found in the MS Series Decoder Data Guide. If the product transfers simple control or status signals such as button SWITCHED OUTPUT presses or switch closures and it does not have a microprocessor on board (or it is desired to avoid protocol development), consider using a remote RELAY VCC control encoder and decoder or a transcoder IC. These chips are available from a wide range of manufacturers including Linx. They take care of all encoding and decoding functions, and generally provide a number of data 1 D6 D5 20 pins to which switches can be directly connected. In addition, address bits VCC 10k 2.2k 2 D7 D4 19 1 16 345678 SSGGLRAEEXNNTLL_DDC__CBBHNAATUULDD01 VVDDDDCC3210CC 111111345678 VCC VCGCND 234567 NNNGVPRCDCCCSNCNSDI GANNNNNNNDTCCCCC 111111012345 GND aucroneint stur soinul da/ elslypt aeptnruodsve ipndrteolydd. uTfochrte sss eteoc I uCmristay ra kareent d aq ntuo eic xakclllyoe wlalen ntdht ewin aeadxyd ptroeen sbssriivinneggly .bo Aaf smdidcu iltrtieiopmnleao ltlye, 220 190 TMXO_DIDE_IND DALTEAA_RINN 1112 8 DATA NC 9 it is a simple task to interface with inexpensive microprocessors, IR, remote 100k RXM-LR control or modem ICs. GND LICAL-DEC-MS001 GND It is always important to separate the types of transmissions that are Figure 15: LR Series Receiver and MS Series Decoder technically possible from those that are legally allowable in the country The receiver can also be connected to a GPIO of a microcontroller in of intended operation. Linx Application Notes AN-00125, AN-00128 applications that use a custom protocol. No buffering is generally required and AN-00140 should be reviewed, along with Part 15, Section 231 of to drive a microcontroller input. Exceptions to this include systems where the Code of Federal Regulations for further details regarding acceptable the microcontroller is operating at a different voltage from the receiver. In transmission content in the US All of these documents can be downloaded these cases the designer should take care to use voltage translator circuits from the Linx website at www.linxtechnologies.com. as appropriate. Another area of consideration is that the data structure can affect the output power level. The FCC allows output power in the 260 to 470MHz band to be averaged over a 100ms time frame. Because OOK modulation activates the carrier for a ‘1’ and deactivates the carrier for a ‘0’, a data stream that sends more ‘0’s has a lower average output power over 100ms. This allows the instantaneous output power to be increased, thus extending range. – 1 4 – – 1 5 –

Antenna Considerations Helpful Application Notes from Linx The choice of antennas is a It is not the intention of this manual to address in depth many of the issues critical and often overlooked that should be considered to ensure that the modules function correctly design consideration. The range, and deliver the maximum possible performance. We recommend reading performance and legality of an RF the application notes listed in Figure 17 which address in depth key areas link are critically dependent upon the of RF design and application of Linx products. These applications notes are antenna. While adequate antenna available online at www.linxtechnologies.com or by contacting Linx. performance can often be obtained Helpful Application Note Titles by trial and error methods, antenna Note Number Note Title design and matching is a complex Figure 16: Linx Antennas AN-00100 RF 101: Information for the RF Challenged task. Professionally designed antennas such as those from Linx (Figure 16) help ensure maximum performance and FCC and other regulatory AN-00125 Considerations for Operation Within the 260–470MHz Band compliance. AN-00130 Modulation Techniques for Low-Cost RF Data Links AN-00140 The FCC Road: Part 15 from Concept to Approval Linx transmitter modules typically have an output power that is higher AN-00150 Use and Design of T-Attenuation Pads than the legal limits. This allows the designer to use an inefficient antenna AN-00160 Considerations for Sending Data over a Wireless Link such as a loop trace or helical to meet size, cost or cosmetic requirements AN-00232 General Considerations for Sending Data with the LC Series and still achieve full legal output power for maximum range. If an efficient AN-00500 Antennas: Design, Application, Performance antenna is used, then some attenuation of the output power will likely be AN-00501 Understanding Antenna Specifications and Operation needed. This can easily be accomplished by using the LADJ line. Figure 17: Helpful Application Note Titles A receiver antenna should be optimized for the frequency or band in Protocol Guidelines which the receiver operates and to minimize the reception of off-frequency While many RF solutions impose data formatting and balancing signals. The efficiency of the receiver’s antenna is critical to maximizing requirements, Linx RF modules do not encode or packetize the signal range performance. Unlike the transmitter antenna, where legal operation content in any manner. The received signal will be affected by such factors may mandate attenuation or a reduction in antenna efficiency, the receiver’s as noise, edge jitter and interference, but it is not purposefully manipulated antenna should be optimized as much as is practical. or altered by the modules. This gives the designer tremendous flexibility for protocol design and interface. It is usually best to utilize a basic quarter-wave whip until your prototype product is operating satisfactorily. Other antennas can then be evaluated Despite this transparency and ease of use, it must be recognized that there based on the cost, size and cosmetic requirements of the product. are distinct differences between a wired and a wireless environment. Issues Additional details are in Application Note AN-00500. such as interference and contention must be understood and allowed for in the design process. To learn more about protocol considerations, read Linx Application Note AN-00160. Interference or changing signal conditions can corrupt 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. – 1 6 – – 1 7 –

Interference Considerations Pad Layout The RF spectrum is crowded and the potential for conflict with unwanted The pad layout diagram in Figure 18 is designed to facilitate both hand and sources of RF is very real. While all RF products are at risk from automated assembly. interference, its effects can be minimized by better understanding its characteristics. 0.065" 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 0.610" 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 0.070" own design with a Linx evaluation board can help to determine if and at what level design-specific interference is present. 0.100" External interference can manifest itself in a variety of ways. Low-level interference produces noise and hashing on the output and reduces the Figure 18: Recommended PCB Layout link’s overall range. Board Layout Guidelines The module’s design makes integration straightforward; however, it High-level interference is caused by nearby products sharing the same is still critical to exercise care in PCB layout. Failure to observe good frequency or from near-band high-power devices. It can even come from layout techniques can result in a significant degradation of the module’s your own products if more than one transmitter is active in the same area. performance. A primary layout goal is to maintain a characteristic It is important to remember that only one transmitter at a time can occupy 50-ohm impedance throughout the path from the antenna to the module. a frequency, regardless of the coding of the transmitted signal. This type of Grounding, filtering, decoupling, routing and PCB stack-up are also interference is less common than those mentioned previously, but in severe important considerations for any RF design. The following section provides cases it can prevent all useful function of the affected device. some basic design guidelines. Although technically not interference, multipath is also a factor to be During prototyping, the module should be soldered to a properly laid-out understood. Multipath is a term used to refer to the signal cancellation circuit board. The use of prototyping or “perf” boards results in poor effects that occur when RF waves arrive at the receiver in different phase performance and is strongly discouraged. Likewise, the use of sockets relationships. This effect is a particularly significant factor in interior can have a negative impact on the performance of the module and is environments where objects provide many different signal reflection paths. discouraged. Multipath cancellation results in lowered signal levels at the receiver and shorter useful distances for the link. The module should, as much as reasonably possible, be isolated from other components on your PCB, especially high-frequency circuitry such as crystal oscillators, switching power supplies, and high-speed bus lines. When possible, separate RF and digital circuits into different PCB regions. – 1 8 – – 1 9 –

Make sure internal wiring is routed away from the module and antenna and Microstrip Details is secured to prevent displacement. A transmission line is a medium whereby RF energy is transferred from one place to another with minimal loss. This is a critical factor, especially Do not route PCB traces directly under the module. There should not be in high-frequency products like Linx RF modules, because the trace any copper or traces under the module on the same layer as the module, leading to the module’s antenna can effectively contribute to the length just bare PCB. The underside of the module has traces and vias that could of the antenna, changing its resonant bandwidth. In order to minimize short or couple to traces on the product’s circuit board. loss and detuning, some form of transmission line between the antenna and the module should be used unless the antenna can be placed very The Pad Layout section shows a typical PCB footprint for the module. A close (<1/8in) to the module. One common form of transmission line is a ground plane (as large and uninterrupted as possible) should be placed on coax cable and another is the microstrip. This term refers to a PCB trace a lower layer of your PC board opposite the module. This plane is essential running over a ground plane that is designed to serve as a transmission line for creating a low impedance return for ground and consistent stripline between the module and the antenna. The width is based on the desired performance. characteristic impedance of the line, the thickness of the PCB and the dielectric constant of the board material. For standard 0.062in thick FR-4 Use care in routing the RF trace between the module and the antenna board material, the trace width would be 111 mils. The correct trace width or connector. Keep the trace as short as possible. Do not pass it under can be calculated for other widths and materials using the information in the module or any other component. Do not route the antenna trace on Figure 19 and examples are provided in Figure 20. Software for calculating multiple PCB layers as vias add inductance. Vias are acceptable for tying microstrip lines is also available on the Linx website. together ground layers and component grounds and should be used in Trace multiples. Board Each of the module’s ground pins should have short traces tying Ground plane immediately to the ground plane through a via. Bypass caps should be low ESR ceramic types and located directly adjacent to the pin they are serving. A 50-ohm coax should be used for connection to an external antenna. A 50-ohm transmission line, such as a microstrip, stripline or coplanar waveguide should be used for routing RF on the PCB. The Microstrip Details section provides additional information. In some instances, a designer may wish to encapsulate or “pot” the Figure 19: Microstrip Formulas product. There are a wide variety of potting compounds with varying dielectric properties. Since such compounds can considerably impact Example Microstrip Calculations RF performance and the ability to rework or service the product, it is Width / Height Effective Dielectric Characteristic Dielectric Constant Ratio (W / d) Constant Impedance (Ω) the responsibility of the designer to evaluate and qualify the impact and 4.80 1.8 3.59 50.0 suitability of such materials. 4.00 2.0 3.07 51.0 2.55 3.0 2.12 48.8 Figure 20: Example Microstrip Calculations – 2 0 – – 2 1 –

Production Guidelines Reflow Temperature Profile The module is housed in a hybrid SMD package that supports hand and The single most critical stage in the automated assembly process is the automated assembly techniques. Since the modules contain discrete reflow stage. The reflow profile in Figure 23 should not be exceeded components internally, the assembly procedures are critical to ensuring because excessive temperatures or transport times during reflow will the reliable function of the modules. The following procedures should be irreparably damage the modules. Assembly personnel need to pay careful reviewed with and practiced by all assembly personnel. attention to the oven’s profile to ensure that it meets the requirements necessary to successfully reflow all components while still remaining Hand Assembly within the limits mandated by the modules. The figure below shows the Pads located on the bottom recommended reflow oven profile for the modules. Soldering Iron of the module are the primary 300 Recommended RoHS Profile Recommended Non-RoHS Profile Tip Max RoHS Profile mounting surface (Figure 21). 255°C Since these pads are inaccessible 250 235°C during mounting, castellations 217°C Solder that run up the side of the module C) 200 185°C have been provided to facilitate PCB Pads Castellations oure ( 180°C solder wicking to the module’s erat 150 p underside. This allows for very Figure 21: Soldering Technique em 125°C T quick hand soldering for prototyping and small volume production. If the 100 recommended pad guidelines have been followed, the pads will protrude slightly past the edge of the module. Use a fine soldering tip to heat the 50 board pad and the castellation, then introduce solder to the pad at the module’s edge. The solder will wick underneath the module, providing 0 30 60 90 120 150 180 210 240 270 300 330 360 reliable attachment. Tack one module corner first and then work around the Time (Seconds) device, taking care not to exceed the times in Figure 22. Figure 23: Maximum Reflow Temperature Profile Shock During Reflow Transport Warning: Pay attention to the absolute maximum solder times. Since some internal module components may reflow along with the Absolute Maximum Solder Times components placed on the board being assembled, it is imperative that Hand Solder Temperature: +427ºC for 10 seconds for lead-free alloys the modules not be subjected to shock or vibration during the time solder is liquid. Should a shock be applied, some internal components could be Reflow Oven: +255ºC max (see Figure 23) lifted from their pads, causing the module to not function properly. Figure 22: Absolute Maximum Solder Times Washability Automated Assembly The modules are wash-resistant, but are not hermetically sealed. Linx For high-volume assembly, the modules are generally auto-placed. recommends wash-free manufacturing; however, the modules can be The modules have been designed to maintain compatibility with reflow subjected to a wash cycle provided that a drying time is allowed prior processing techniques; however, due to their hybrid nature, certain aspects to applying electrical power to the modules. The drying time should be of the assembly process are far more critical than for other component sufficient to allow any moisture that may have migrated into the module types. Following are brief discussions of the three primary areas where to evaporate, thus eliminating the potential for shorting damage during power-up or testing. If the wash contains contaminants, the performance caution must be observed. may be adversely affected, even after drying. – 2 2 – – 2 3 –

General Antenna Rules plane as possible in proximity to the base of the antenna. In cases The following general rules should help in maximizing antenna performance. where the antenna is remotely located or the antenna is not in close proximity to a circuit board, ground plane or grounded metal case, a 1. Proximity to objects such as a user’s hand, body or metal objects will metal plate may be used to maximize the antenna’s performance. cause an antenna to detune. For this reason, the antenna shaft and tip should be positioned as far away from such objects as possible. 5. Remove the antenna as far as possible from potential interference sources. Any frequency of sufficient amplitude to enter the receiver’s 2. Optimum performance is obtained from a ¼- or ½-wave straight whip front end will reduce system range and can even prevent reception mounted at a right angle to the ground plane (Figure 24). In many entirely. Switching power supplies, oscillators or even relays can also cases, this isn’t desirable for practical or ergonomic reasons, thus, be significant sources of potential interference. The single best weapon an alternative antenna style such as a helical, loop or patch may be against such problems is attention to placement and layout. Filter the utilized and the corresponding sacrifice in performance accepted. module’s power supply with a high-frequency bypass capacitor. Place adequate ground plane under potential sources of noise to shunt noise to ground and prevent it from coupling to the RF stage. Shield noisy board areas whenever practical. 6. In some applications, it is advantageous to place the module and OPTIMUM antenna away from the main equipment (Figure 26). This can avoid NOT RECOMMENDED USABLE interference problems and allows the antenna to be oriented for Figure 24: Ground Plane Orientation optimum performance. Always use 50Ω coax, like RG-174, for the OPTIMUM remote feed. NOT RECOMMENDED USABLE 3. If an internal antenna is to be used, keep it awCAaSyE from other metal components, particularly large items like transformers, batteries, GROUND PLANE PCB tracks and NgUrTound planes. In ma(MnyA Yc BaEs NeEsE, DthEDe) space around the antenna is as important as the antenna itself. Objects in close proximity CASE to the antenna can cause direct detuning, while those farther away will alter the antenna’s symmetry. GROUND PLANE NUT (MAY BE NEEDED) 4. In many antenna designs, particularly ¼-wave whips, the ground plane acts as a counterpoise, forming, in essence, Figure 26: Remote Ground Plane VERTICAL λ/4 GROUNDED a ½-wave dipole (Figure 25). For this reason, ANTENNA (MARCONI) adequate ground plane area is essential. E DIPOLE The ground plane can be a metal case or ELEMENT ground-fill areas on a circuit board. Ideally, it λ/4 should have a surface area less than or equal to the overall length of the ¼-wave radiating I element. This is often not practical due to GROUND size and configuration constraints. In these PLANE instances, a designer must make the best use VIRTUAL λ/4 λ/4 DIPOLE of the area available to create as much ground Figure 25: Dipole Antenna – 2 4 – – 2 5 –

Common Antenna Styles Loop Style There are hundreds of antenna styles and variations that can be employed A loop or trace style antenna is normally printed with Linx RF modules. Following is a brief discussion of the styles most directly on a product’s PCB (Figure 30). This commonly utilized. Additional antenna information can be found in Linx makes it the most cost-effective of antenna Application Notes AN-00100, AN-00140, AN-00500 and AN-00501. Linx styles. The element can be made self-resonant or antennas and connectors offer outstanding performance at a low price. externally resonated with discrete components, but its actual layout is usually product specific. Whip Style Despite the cost advantages, loop style antennas Figure 30: Loop or Trace Antenna A whip style antenna (Figure 27) provides are generally inefficient and useful only for short outstanding overall performance and stability. range applications. They are also very sensitive to changes in layout and A low-cost whip can be easily fabricated from PCB dielectric, which can cause consistency issues during production. a wire or rod, but most designers opt for the In addition, printed styles are difficult to engineer, requiring the use of consistent performance and cosmetic appeal of expensive equipment including a network analyzer. An improperly designed a professionally-made model. To meet this need, loop will have a high VSWR at the desired frequency which can cause Linx offers a wide variety of straight and reduced instability in the RF stage. height whip style antennas in permanent and connectorized mounting styles. Linx offers low-cost planar (Figure 31) and chip Figure 27: Whip Style Antennas antennas that mount directly to a product’s PCB. The wavelength of the operational frequency These tiny antennas do not require testing and determines an antenna’s overall length. Since a full 234 provide excellent performance despite their small L = wavelength is often quite long, a partial ½- or ¼-wave FMHz size. They offer a preferable alternative to the often antenna is normally employed. Its size and natural Figure 28: problematic “printed” antenna. Figure 31: SP Series radiation resistance make it well matched to Linx L = length in feet of “Splatch” and uSP quarter-wave length “MicroSplatch” Antennas modules. The proper length for a straight ¼-wave can F = operating frequency be easily determined using the formula in Figure 28. It is in megahertz 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. Specialty Styles Linx offers a wide variety of specialized antenna styles (Figure 29). 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. Figure 29: Specialty Style Antennas – 2 6 – – 2 7 –

Regulatory Considerations Questions regarding interpretations of the Part 2 and Part 15 rules or the measurement procedures used to test intentional radiators such as Linx RF Note: Linx RF modules are designed as component devices that require modules for compliance with the technical standards of Part 15 should be external components to function. The purchaser understands that addressed to: additional approvals may be required prior to the sale or operation of the device, and agrees to utilize the component in keeping with all laws Federal Communications Commission governing its use in the country of operation. Equipment Authorization Division When working with RF, a clear distinction must be made between what Customer Service Branch, MS 1300F2 is technically possible and what is legally acceptable in the country where 7435 Oakland Mills Road operation is intended. Many manufacturers have avoided incorporating RF Columbia, MD, US 21046 into their products as a result of uncertainty and even fear of the approval Phone: + 1 301 725 585 | Fax: + 1 301 344 2050 and certification process. Here at Linx, our desire is not only to expedite the Email: labinfo@fcc.gov design process, but also to assist you in achieving a clear idea of what is involved in obtaining the necessary approvals to legally market a completed ETSI Secretaria product. 650, Route des Lucioles 06921 Sophia-Antipolis Cedex For information about regulatory approval, read AN-00142 on the Linx FRANCE website or call Linx. Linx designs products with worldwide regulatory Phone: +33 (0)4 92 94 42 00 approval in mind. Fax: +33 (0)4 93 65 47 16 In the United States, the approval process is actually quite straightforward. International approvals are slightly more complex, although Linx modules The regulations governing RF devices and the enforcement of them are are designed to allow all international standards to be met. If the end the responsibility of the Federal Communications Commission (FCC). The product is to be exported to other countries, contact Linx to determine the regulations are contained in Title 47 of the United States Code of Federal specific suitability of the module to the application. Regulations (CFR). Title 47 is made up of numerous volumes; however, all regulations applicable to this module are contained in Volume 0-19. All Linx modules are designed with the approval process in mind and thus It is strongly recommended that a copy be obtained from the FCC’s much of the frustration that is typically experienced with a discrete design is website, the Government Printing Office in Washington or from your local eliminated. Approval is still dependent on many factors, such as the choice government bookstore. Excerpts of applicable sections are included of antennas, correct use of the frequency selected and physical packaging. with Linx evaluation kits or may be obtained from the Linx Technologies While some extra cost and design effort are required to address these website, www.linxtechnologies.com. In brief, these rules require that any issues, the additional usefulness and profitability added to a product by RF device that intentionally radiates RF energy be approved, that is, tested for makes the effort more than worthwhile. compliance and issued a unique identification number. This is a relatively painless process. Final compliance testing is 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 the completed product has passed, an ID number is issued that is to be clearly placed on each product manufactured. – 2 8 – – 2 9 –

Notes – 3 0 – – 3 1 –

Linx Technologies 159 Ort Lane Merlin, OR, US 97532 Phone: +1 541 471 6256 Fax: +1 541 471 6251 www.linxtechnologies.com Disclaimer 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. ©2015 Linx Technologies. All rights reserved. The stylized Linx logo, Wireless Made Simple, WiSE, CipherLinx and the stylized CL logo are trademarks of Linx Technologies.

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