LR Series
Receiver Module
Data Guide
! 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
damage if improperly or inadvertently triggered, particularly in industrial
settings or other applications implicating life-safety concerns (“Life and
Property Safety Situations”).
Table of Contents
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NO OEM LINX REMOTE CONTROL OR FUNCTION MODULE
SHOULD EVER BE USED IN LIFE AND PROPERTY SAFETY
SITUATIONS. No OEM Linx Remote Control or Function Module
should be modified for Life and Property Safety Situations. Such
modification cannot provide sufficient safety and will void the product’s
regulatory certification and warranty.
2^
Customers may use our (non-Function) Modules, Antenna and
Connectors as part of other systems in Life Safety Situations, but
only with necessary and industry appropriate redundancies and
in compliance with applicable safety standards, including without
limitation, ANSI and NFPA standards. It is solely the responsibility
of any Linx customer who uses one or more of these products to
incorporate appropriate redundancies and safety standards for the Life
and Property Safety Situation application.
7^
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/
decoder to validate the data. Without validation, any signal from
another unrelated transmitter in the environment received by the module
could inadvertently trigger the action.
All RF products are susceptible to RF interference that can prevent
communication. RF products without frequency agility or hopping
implemented are more subject to interference. This module does not
have a frequency hopping protocol built in.
Do not use any Linx product over the limits in this data guide.
Excessive voltage or extended operation at the maximum voltage could
cause product failure. Exceeding the reflow temperature profile could
cause product failure which is not immediately evident.
Do not make any physical or electrical modifications to any Linx
product. This will void the warranty and regulatory and UL certifications
and may cause product failure which is not immediately evident.
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Description
Features
Applications
Ordering Information
Absolute Maximum Ratings
Electrical Specifications
Typical Performance Graphs
Pin Assignments
Pin Descriptions
Module Description
Theory of Operation
Using the RSSI Pin
The Data Output
Using the PDN Line
Power Supply Requirements
ESD Concerns
Typical Applications
Transferring Data
Antenna Considerations
Helpful Application Notes from Linx
Protocol Guidelines
Interference Considerations
Pad Layout
Board Layout Guidelines
Microstrip Details
Production Guidelines
Hand Assembly
Automated Assembly
General Antenna Rules
26^
Common Antenna Styles
28^ Regulatory Considerations
30^ Notes
LR Series Receiver Module
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
RXM-315-LR
(16mm)
LOT RRxxxx
advanced synthesized architecture achieves an
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
Figure 1: Package Dimensions
Linx transmitter, a reliable wireless link is formed
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 cost
PLL-synthesized architecture
Direct serial interface
Data rates up to 10,000bps
No external RF components
required
• Low power consumption
• Low supply voltage (2.1 to
3.6VDC)
• Compact surface-mount package
• Wide temperature range
• RSSI and Power-down function
• No production tuning
Applications
•
•
•
•
•
•
Remote control
Keyless entry
Garage/gate openers
Lighting control
Medical monitoring/call systems
Remote industrial monitoring
•
•
•
•
•
•
– 1 –
Periodic data transfer
Home/industrial automation
Fire/security alarms
Remote status/position sensing
Long-range RFID
Wire elimination
Revised 3/18/2015
Ordering Information
Electrical Specifications
Ordering Information
LR Series Receiver Specifications
Part Number
Description
Parameter
TXM-315-LR
315MHz Transmitter
Power Supply
TXM-418-LR
418MHz Transmitter
Operating Voltage
TXM-433-LR
433MHz Transmitter
RXM-315-LR
315MHz Receiver
Supply Current
RXM-418-LR
418MHz Receiver
Power Down Current
RXM-433-LR
433MHz Receiver
Receiver Section
EVAL-***-LR
LR Series Basic Evaluation Kit
Receive Frequency Range
Symbol
Min.
Typ.
Max.
Units
VCC
2.7
3.0
3.6
VDC
4.3
5.0
5.2
VDC
lCC
4.0
5.2
7.0
mA
lPDN
20.0
28.0
35.0
µA
With Dropping Resistor
*** = 315, 418 (Standard), 433MHz
Receivers are supplied in tubes of 18 pcs.
315
MHz
RXM-418-LR
418
MHz
RXM-433-LR
433.92
MHz
Center Frequency Accuracy
Absolute Maximum Ratings
–50
LO Feedthrough
IF Frequency
Absolute Maximum Ratings
Noise Bandwidth
Supply Voltage VCC
−0.3
to
+3.6
VDC
Supply Voltage VCC, Using Resistor
−0.3
to
+5.2
VDC
Any Input or Output Pin
−0.3
to
VCC + 0.3
VDC
RF Input
0
dBm
Operating Temperature
−40
to
+70
ºC
Storage Temperature
−40
to
+85
ºC
Soldering Temperature
+260ºC for 10 seconds
Exceeding any of the limits of this section may lead to permanent damage to the device.
Furthermore, extended operation at these maximum ratings may reduce the life of this
device.
FIF
N3DB
Data Rate
+50
5
kHz
–80
dBm
2,5
10.7
MHz
5
280
100
kHz
10,000
bps
Data Output:
Logic Low
VOL
0.0
VDC
3
Logic High
VOH
3.0
VDC
3
Power Down Input:
Logic Low
VIL
Logic High
VIH
Receiver Sensitivity
0.4
VDC
–118
dBm
4
dB
5
Hz
5
VCC–0.4
–106
VDC
–112
RSSI / Analog
Dynamic Range
Figure 3: Absolute Maximum Ratings
1,5
FC
RXM-315-LR
Figure 2: Ordering Information
Notes
80
Analog Bandwidth
50
5,000
Gain
16
mv /
dB
5
Voltage with No Carrier
1.5
V
5
50
Ω
5
Antenna Port
RF Input Impedance
RIN
Timing
Receiver Turn-On Time
– 2 –
Via VCC
3.0
7.0
10.0
ms
5,6
Via PDN
0.04
0.25
0.50
nS
5,6
– 3 –
Typical Performance Graphs
LR Series Receiver Specifications Continued
Parameter
Symbol
Min.
Max. Time Between
Transitions
Typ.
Max.
10.0
Units
Notes
ms
5
Supply
Environmental
Operating Temperature
Range
1.
2.
3.
4.
5.
6.
–40
+70
ºC
5
The LR can utilize a 4.3 to 5.2VDC supply provided a 330Ω resistor is placed in series
with VCC.
Into a 50Ω load.
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.
For BER of 10–5 at 1,200bps.
Characterized, but not tested.
Time to valid data output.
RX Data
Figure 4: Electrical Specifications
Figure 5: Turn-On Time from VCC
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
this precaution may result in module damage or failure.
PDN
RX Data
Figure 6: Turn-On Time from PDN
– 4 –
– 5 –
Pin Assignments
5.40
1
2
3
4
5
6
7
8
Supply Current (mA)
5.35
5.30
5.25
With Dropping
Resistor
5.20
5.15
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
NC
NC
NC
GND
VCC
PDN
RSSI
DATA
ANT
GND
NC
NC
NC
NC
NC
NC
16
15
14
13
12
11
10
9
Supply Voltage (VDC)
Figure 9: LR Series Receiver Pinout (Top View)
Figure 7: Consumption vs. Supply
Pin Descriptions
Pin Descriptions
RFIN > –35dBm
No RFIN
Figure 8: RSSI Response Time
Pin Number
Name
I/O
Description
1
NC
—
No Connection
2
NC
—
No Connection
3
NC
—
No Connection
4
GND
—
Analog Ground
5
VCC
—
Supply Voltage
6
PDN
I
Power Down. Pulling this line low will place
the receiver into a low-current state. The
module will not be able to receive a signal in
this state.
7
RSSI
O
Received Signal Strength Indicator. This line
will supply an analog voltage that is proportional to the strength of the received signal.
8
DATA
O
Digital Data Output. This line will output the
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
receiver, capable of receiving serial data at up to 10,000bps. Its exceptional
sensitivity results in outstanding range performance. The LR’s compact
surface-mount package is friendly to automated or hand production. LR
Series modules are capable of meeting the regulatory requirements of
many domestic and international applications.
The LR Series receiver is designed
to recover data sent by an AM
Data
or Carrier-Present Carrier-Absent
(CPCA) transmitter, also referred to
as CW or On-Off Keying (OOK). This Carrier
type of modulation represents a logic
low '0’ by the absence of a carrier
and a logic high ‘1’ by the presence Figure 12: CPCA (AM) Modulation
of a carrier. This modulation method affords numerous benefits. The two
most important are: 1) cost-effectiveness due to design simplicity and 2)
higher allowable output power and thus greater range in countries (such as
the U.S.) that average output power measurements over time. Please refer
to Linx Application Note AN-00130 for a further discussion of modulation
techniques.
The receiver's outstanding typical sensitivity of –112dBm enables system
ranges of up to 1.5 miles (2,500m) when paired with an LR Series
transmitter operating at full power and good antennas. Legal regulations
in the various countries will require the transmitter output power to be
reduced which will reduce range. Following the legal output limit for
transmitters in the United States, systems based on the LR Series can
achieve ranges of up to 3,000 feet (1,000m).
50Ω RF IN
(Antenna)
Band Select
Filter
10.7MHz
IF Filter
0˚
∑
LNA
90˚
PLL
Data Slicer
Limiter
Data Out
+
RSSI/Analog
VCO
XTAL
Figure 11: LR Series Receiver Block Diagram
– 8 –
The LR receiver utilizes an advanced single-conversion superheterodyne
architecture. Transmitted signals enter the module through a 50Ω RF
port intended for single-ended connection to an external antenna. RF
signals entering the antenna are filtered and then amplified by an NMOS
cascode Low Noise Amplifier (LNA). The filtered, amplified signal is then
down-converted to a 10.7MHz Intermediate Frequency (IF) by mixing it
with a low-side Local Oscillator (LO). The LO frequency is generated by
a Voltage Controlled Oscillator (VCO) locked by a Phase-Locked Loop
(PLL) frequency synthesizer that utilizes a precision crystal reference. The
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.
– 9 –
Using the RSSI Pin
The Data Output
The receiver’s Received Signal Strength Indicator (RSSI) line outputs a
voltage that is proportional to the incoming signal strength. This line has
a dynamic range of 80dB (typical) and can serve a variety of functions. It
should be noted that the RSSI levels and dynamic range will vary slightly
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
that from the intended transmitter; therefore, it should be used only to
qualify the level and presence of a signal.
The CMOS-compatible data output is normally used to drive a digital
decoder IC or a microprocessor that is performing the data decoding. It
does not have a large current drive capability so is intended to drive high
impedance loads, such as microprocessor inputs or digital logic gates.
The RSSI output can be utilized during testing or even as a product feature
to assess interference and channel quality by looking at the RSSI level
with all intended transmitters shut off. The RSSI output can also be used
in direction-finding applications, although there are many potential perils to
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
certain threshold. The RSSI output feature adds tremendous versatility for
the creative designer.
The receiver’s output may appear to switch randomly in the absence of a
transmitter. This is a result of random noise in the environment. This noise
can be handled in software by implementing a noise-tolerant protocol
as described in Application Note AN-00160. If a software solution is not
appropriate, the squelch circuit in Figure 13 can be used. This circuit uses
a potentiometer to set a voltage reference. If the RSSI level falls below this
reference then a comparator turns off the DATA line and stops the random
switching.
This circuit is good for reducing the amount of random noise that the
microcontroller must deal with, but it also reduces the sensitivity of the
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
R5
1M
VCC
R2
500k
R6
1M
2
D1
3
RSSI
+
C1
0.1µ
U1
LMV393
6
1
5
+
-
U1
LMV393
7
+
R4
100k
R1
2M
DATA
R3
5M
Figure 13: LR Series Receiver Squelch Circuit
– 10 –
VCC
– 11 –
R7
2M
R8
10k
Squelched Data
Using the PDN Line
Power Supply Requirements
The Power Down (PDN) line can be used to power down the receiver
without the need for an external switch. This line has an internal pull-up, so
when it is held high or simply left floating, the module is active.
The module does not have an internal
Vcc TO
MODULE
voltage regulator, therefore it requires a
clean, well-regulated power source. While
10Ω
it is preferable to power the unit from a
Vcc IN
battery, it can also be operated from a
10µF
power supply as long as noise is less than
20mV. Power supply noise can significantly
affect the receiver sensitivity, therefore;
providing clean power to the module should Figure 14: Supply Filter
be a high priority during design.
The PDN line allows easy control of the receiver state from external
components, like a microcontroller. By periodically activating the receiver,
checking for data, then powering down, the receiver’s average current
consumption can be greatly reduced, saving power in battery-operated
applications.
Note: The voltage on the PDN line should not exceed VCC. When used
with a higher voltage source, such as a 5V microcontroller, an open
collector line should be used or a diode placed in series with the control
line (anode toward the module). Either method avoids damage to the
module by preventing 5V from being placed on the PDN line while
allowing the line to be pulled low.
+
When the PDN line is pulled to ground, the receiver enters a low-current
(
