TXM-869-ES
TXM-916-ES
WIRELESS MADE SIMPLE
®
ES SERIES TRANSMITTER DATA GUIDE
DESCRIPTION
Housed in a tiny SMD package, the ES Series offers
0.510"
an unmatched combination of features, performance,
and cost-effectiveness. The ES utilizes an advanced
FM / FSK-based synthesized architecture to provide
superior performance and noise immunity when
compared to AM / OOK solutions. An outstanding
0.630"
RF MODULE
TXM-916-ES
56kbps maximum data rate and wide-range analog
LOT 1000
capability make the ES Series equally at home with
digital data or analog sources. A host of useful
features including PDN, LADJ, low voltage detect, and
a clock source are provided. The ES operates in the
0.125"
900MHz band, which in North America allows an
unlimited variety of applications, including data links,
audio links, home and industrial automation, security,
Figure 1: Package Dimensions
remote control / command, and monitoring. Like all Linx modules, the ES Series
requires no tuning or external RF components (except an antenna).
FEATURES
Ultra-compact SMD package
FM / FSK modulation
Wide bandwidth (20Hz to 28kHz)
Very low current consumption
Data rates to 56,000bps
User power-down input
Low-voltage detect output
Microprocessor clock output
No production tuning
No external RF components
needed
Precision-frequency synthesized
architecture
Direct interface to analog and
digital sources
Excellent cost / performance ratio
APPLICATIONS INCLUDE
Wireless Data Transfer
ORDERING INFORMATION
Wireless Analog / Audio
PART #
DESCRIPTION
TXM-869-ES
ES Series Transmitter 869MHz
Home / Industrial Automation
TXM-916-ES
ES Series Transmitter 916MHz
Keyless Entry
RXM-869-ES
ES Series Receiver 869MHz
Remote Control
RXM-916-ES
ES Series Receiver 916MHz
Fire / Security Alarms
EVAL-***-ES
Basic Evaluation Kit
Wireless Networks
Master Development System
Remote Status Sensing / Telemetry
MDEV-***-ES
*** = Frequency
Long-Range RFID
Receivers are supplied in tubes of 40 pcs.
RS-232 / 485 Data Links
Voice / Music Links / Intercom
Revised 1/28/08
ELECTRICAL SPECIFICATIONS
Parameter
POWER SUPPLY
Operating Voltage
Supply Current
Power-Down Current
TRANSMIT SECTION
Transmit Frequency:
TXM-916-ES
TXM-869-ES
Center Frequency Accuracy
Output Power
Output Power Control Range
Harmonic Emissions
Frequency Deviation
TXM-916-ES
TXM-869-ES
Data Rate
Analog/Audio Bandwidth
Data Input:
Logic Low
Logic High
Power-Down Input:
Logic Low
Logic High
Analog Input
ANTENNA PORT
RF Output Impedance
TIMING
Transmitter Turn-On Time
Max. Time Between Transitions
ENVIRONMENTAL
Operating Temperature Range
–
0
–
+70
–
–
0.1
–
0.5
–
1.5
5.0
mSec
mSec
7,10
7,11
7
R
OUT
–
50
–
Ω
7
–
–
–
0.0
1.5
0.0
–
–
–
0.7
V
CC
5.0
VDC
VDC
V
P-P
–
–
9
V
IL
V
IH
0.0
3.0
–
–
0.4
5.2
VDC
VDC
8
8
–
–
–
–
90
–
200
20
110
75
–
–
130
130
56,000
28,000
kHz
kHz
bps
Hz
5
5
7
6,7
–
P
O
–
P
H
F
C
–
–
-60
-4
–
–
916.48
869.85
–
0
65
-55
–
–
+60
+4
–
-47
MHz
MHz
kHz
dBm
dB
dBc
4
4
1
2,3
2,3,7
2
V
CC
I
CC
I
PDN
2.1
5.5
–
3.0
7.0
90.0
4.0
8.5
–
VDC
mA
µA
–
–
7
Designation
Min.
Typical
Max.
Units
Notes
ABSOLUTE MAXIMUM RATINGS
Supply voltage V
CC
Any Input or Output Pin
Operating Temperature
Storage Temperature
Soldering Temperature
-0.3
-0.5
0
-40
+216°C
to
+4.0
to V
CC
+ 0.5
to
+70
to
+90
for 15 seconds
VDC
VDC
°C
°C
*NOTE*
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.
PERFORMANCE DATA
These performance parameters are
based on module operation at 25°C
from a 3.0VDC supply unless
otherwise noted. Figure 2 illustrates
the connections necessary for
testing and operation. It is
recommended all ground pins be
connected to the ground plane.
1
2
3
4
5
PDN
ANT
GND
LADJ
VCC LO_V_D
GND /CLK SE
DATA
/CLK
10
9
8
7
6
Figure 2: Test / Basic Application Circuit
TYPICAL PERFORMANCE GRAPHS
40
LADJ to GND (kΩ)
35
30
1
IN
25
20
15
-10
-8.0
-6.0 -4.0 -2.0 -1.0
RF Output Attenuation (dB)
-0.4
-0.2
2
CH1 1.66V
CH2 100mV
250uS
OUT
°
C
Table 1: ES Series Transmitter Specifications
Notes
1. Center frequency measured while modulated with a 0-5V square wave.
2. Into a 50-ohm load.
3. LADJ open.
4. Maximum power when LADJ open, minimum power when LADJ grounded.
5. DATA pin modulated with a 0-5V square wave.
6. The audio bandwidth is wide to accommodate the needs of the data slicer.
7. Characterized, but not tested.
8. The ES is optimized for both 0-5V and 0-3V modulation when sending digital data.
9. Analog signals, including audio, should be AC-coupled.
10. Time to transmitter readiness from the application of power to V
CC
or PDN going high.
11. Maximum time without a data transition.
Figure 3: Level Adjust Attenuation
Figure 4: Square-Wave Modulation Linearity
Tx VCC/PDN
Tx VCC/PDN
1
1
*CAUTION*
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.
Page 2
RX Data
Rx Demodulated Analog Data
2
2
CH1 2.00V
CH2 2.00V
1mS
CH1 2.00V
CH2 500mV
100uS
Figure 5: Tx Powerup to Valid Rx Analog
Figure 6: Tx Powerup to Valid Rx Data
Page 3
PIN ASSIGNMENTS
MODULE DESCRIPTION
The TXM-***-ES module is a single-channel transmitter designed for the wireless
transfer of digital or analog information over distances of up to 1,000 feet
outdoors and up to 500 feet indoors. It is based on a high-performance
synthesized architecture. FM / FSK modulation is utilized to provide superior
performance and noise immunity over AM-based solutions. The ES Series is
incredibly compact and cost-effective when compared with other FM / FSK
devices. Best of all, it is packed with many useful features and capabilities that
offer a great deal of application flexibility to the designer. Some of these features,
which will be discussed in depth in this data guide, are:
/CLK Output (use for an external micro-controller)
LO_V_DET (low-voltage detection)
LADJ
(adjust the RF output power)
The ES Series is offered in the 902-928MHz band, which is free from the legal
restrictions of the lower 260-470MHz band. This gives the designer much more
freedom in the types of applications that can be designed. The 869.85MHz
version allows for the same freedom of design in European applications.
RF Amplifier
Precision
Crystal
Data In
PLL Frequency
Synthesizer
LC
Filter
Antenna Port
1
2
3
4
5
PDN
ANT
LADJ
GND
VCC LO_V_D
GND /CLK SE
DATA
/CLK
10
9
8
7
6
Figure 7: ES Series Transmitter Pinout (Top View)
PIN DESCRIPTIONS
Pin #
1
Name
PDN
Description
Power Down. Pulling this line low will place the transmitter
into a low-current state. The module will not be able to
transmit a signal in this state.
2
LADJ
Level Adjust. This line can be used to adjust the output
power level of the transmitter. Connecting to Vcc will give
the highest output, while placing a resistor to GND will
lower the output level (see Figure 4 on Page 3).
Supply Voltage
Analog Ground
Analog or Digital Data Input
Divided Clock Output
Clock Frequency Selection. Logic low selects divide by
256, logic high selects divide by 1,024.
Low Voltage Detect. This line goes low when V
CC
is less
than 2.15V.
Analog Ground
50-ohm RF Output
/CLK SEL
Frequency Divider
256 / 1,024
/CLK Output
3
4
5
6
7
V
CC
GND
DATA
/CLK
/CLK SEL
Figure 8: ES Series Transmitter Block Diagram
THEORY OF OPERATION
The ES Series FM / FSK transmitter is capable of generating 1mW of output
power into a 50-ohm load while suppressing harmonics and spurious emissions
to within legal limits. The transmitter is comprised of a VCO and a crystal-
controlled frequency synthesizer. The frequency synthesizer, referenced to a
precision crystal, locks the VCO to achieve a high-Q, low phase-noise oscillator.
The transmitter operates by directly modulating the crystal with the baseband
signal present on the DATA line. Pulling the crystal in this manner achieves the
desired deviation and linearity. If the transmitter’s VCO were modulated, the
frequency synthesizer would track out much of the deviation within the
bandwidth of the loop filter (this is a common limitation of most synthesized FM
transmitters). The carrier is then amplified and filtered before being output on the
50-ohm ANT line.
The frequency of the Divided Clock output is determined by the state of the Clock
Frequeny Selection line. A low on the Select line will generate a signal on the
clock output that is the center frequency divided by 256, a high will be the center
frequency divided by 1,024.
8
9
10
LO_V_D
GND
ANT
Page 4
Page 5
USING THE DIVIDED CLOCK OUTPUT (/CLK)
When the ES is used with a microcontroller, the divided clock output (/CLK)
saves cost and space by eliminating the need for a crystal or other frequency
reference for the microprocessor. This line is an open collector output, so an
external pull-up resistor (R
L
) should be connected between this line and the
positive supply voltage. The value of R
L
is calculated using two factors:
1) Determine the clock frequency (f
CLKOUT
). If /CLK SE is open, the /CLK output
will be the Tx center frequency (in MHz) divided by 1,024; if /CLK SEL is
grounded, it will be /256.
2) Determine the load capacitance of the PCB plus the microcontroller’s input
capacitance (C
LD
in pF).
Using these two factors, the value of R
L
can be easily calculated:
“/256” R
L
= 1000/(f
CLKOUT
*8*C
LD
)
Example:
“/1024” R
L
= 1000/(f
CLKOUT
*8*C
LD
)
Example:
USING THE PDN PIN
The Power Down (PDN) line can be used to power down the transmitter 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 will be active.
When the PDN line is pulled to ground, the transmitter will enter into a low-
current (<95µA) power-down mode. During this time, the transmitter is off and
cannot perform any function. The startup time coming out of power-down will be
the same as applying V
CC
.
The PDN line allows easy control of the transmitter state from external
components, such as a microcontroller. By periodically activating the transmitter,
sending data, then powering down, the transmitter’s average current
consumption can be greatly reduced, saving power in battery operated
applications.
USING THE LO_V_D PIN
In many instances, the transmitter may be employed in a battery-powered
device. In such applications, it is often useful to be able to sense a low-battery
condition, either to signal the need for battery replacement or to power down
components that might otherwise operate unpredictably. Normally, this
supervisory function would require additional circuitry, but the ES Series
transmitter includes the function on-board.
The Low Voltage Detect line (LO_V_D) will transition low when the supply
voltage to the transmitter falls below a typical threshold of 2.15VDC. This output
can be tied directly to the module’s PDN line to shut off the transmitter, or used
to indicate the low voltage condition to an external circuit or microprocessor. The
output could also be used to provide a visual indication of the low power
condition via a LED, although a buffer transistor would generally be required to
provide an adequate drive level.
The output can also be monitored in applications with a power supply as a
safeguard against brownout conditions.
For /256: 1000/((916.48/256)x8x5)=6.98kΩ For /1024: 1000/((916.48/1024)x8x5)=27.9kΩ
USING LADJ
The transmitter’s output power can be externally adjusted by approximately
-65dBm using the LADJ line. This eliminates the need for external attenuation
and allows the transmitter’s power to be easily adjusted for range control, lower
power consumption, or to meet legal requirements. This line can also be
modulated to allow the ES to operate as an AM transmitter; however, this is not
recommended since the ES receiver is designed only for FM / FSK recovery and
the performance and noise immunity advantages of FM would be lost.
When the LADJ line is open, the output power will be at its maximum and the
transmitter will draw 7mA typically. When LADJ is at 0V, the output power will be
at its minimum and the transmitter will draw 3mA typically.
To set the transmit power at a particular level, simply create a voltage reference
at the LADJ line at an appropriate level to achieve the desired output power. The
easiest way to accomplish this is with an appropriate value resistor from the
LADJ line to ground. This resistor works in combination with the internal supply
pull-up to create a voltage divider. Page 3 of this data guide features a chart
showing typical resistor values and corresponding attenuation levels.
The LADJ line 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. Often it is wise to connect the LADJ line to a variable resistor so that the
test lab can precisely adjust the output power to the maximum threshold allowed
by law. The resistor’s value can then 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 so that it can be used if needed.
For more sophisticated designs, LADJ may also be controlled by a DAC or digital
potentiometer to allow precise and digitally variable output power control.
In any case where the voltage on the LADJ line may fall below 1.5VDC, a low-
value ceramic capacitor (200 to 4,700pF) must be placed from the module’s
power supply to the LADJ pin. This is necessary to meet the module’s minimum
enable voltage at start-up.
Page 6
POWER SUPPLY REQUIREMENTS
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.
Vcc TO
MODULE
10Ω
Vcc IN
+
10μF
A 10Ω resistor in series with the supply followed by a
10µF tantalum capacitor from V
CC
to ground will help in cases where the quality
of supply power is poor. Note that operation from 4.3 to 5.2 volts requires the
use of an external 270Ω resistor placed in series with the supply to prevent V
CC
from exceeding 4.0 volts, so the dropping resistor can take the place of the 10Ω
resistor in the supply filter. These values may need to be adjusted depending on
the noise present on the supply line.
Page 7
Figure 9: Supply Filter
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.
TYPICAL APPLICATIONS
USING THE ES SERIES TRANSMITTER FOR ANALOG APPLICATIONS
The ES Series is an excellent choice for sending analog information, including
audio. The ability of the ES to transmit combinations of analog and digital content
opens many new opportunities for design creativity.
Simple or complex analog signals within the specified audio bandwidth and input
levels may be connected directly to the transmitter’s DATA line. The transmitter
input is high impedance (500kΩ) and can be directly driven by a wide variety of
sources, ranging from a single frequency to complex content, such as audio.
Analog sources should provide 0V to no more than 5V
P-P
maximum waveform
and should be AC-coupled into the DATA line. The size of the coupling capacitor
should be large enough to ensure the passage of all desired frequencies. Since
the modulation voltage applied to the DATA line determines the carrier deviation,
distortion can occur if the DATA line is over-driven. The actual level of the input
waveform should be adjusted to achieve optimum in-circuit results.
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.
Page 8
0-Vcc Audio Source
1
2
3
4
5
0.1µF
PDN
ANT
LADJ
GND
VCC LO_V_D
GND /CLK SE
DATA
/CLK
10
9
8
7
6
Figure 10: AC Coupling An Audio Source
USING THE ES SERIES TRANSMITTER FOR DIGITAL APPLICATIONS
The ES Series transmitter is equally capable at accommodating digital data. The
transmitter input is high impedance (500k) and can be directly driven by a wide
variety of sources including microprocessors and encoder ICs.
When the transmitter will be used to transmit digital data, the DATA line is best
driven from a 3 to 5V source. The transmitter is designed to give an average
deviation of 115kHz with a 5V square wave input, and 75kHz with 3V square
wave input. Either choice will achieve maximum performance.
Data adhering to different electrical level standards, such as RS-232, will require
buffering or conversion to logic level voltages. In the case of RS-232, such
buffering is easily handled with widely available ICs, such as the MAX232, which
is used on the ES Series Master Development System. The Linx SDM-USB-QS
can be used to convert between USB compliant signals and logic level voltages.
Page 9
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