TXM-418-LC View Datasheet(PDF) - Unspecified
Part Name
Description
Manufacturer
TXM-418-LC Datasheet PDF : 11 Pages
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PIN ASSIGNMENTS
1 GND
GND 8
2 DATA VCC 7
3 GND
GND 6
4 LADJ/GND ANT 5
Figure 8: LC Series Transmitter Pinout (Top View)
PIN DESCRIPTIONS
Pin #
1
2
3
Name
GND
DATA
GND
Description
Analog Ground
Digital Data Input
Analog Ground
Level Adjust. This line can be used to adjust the output
4
LADJ/GND
power level of the transmitter. Connecting to ground will
give the highest output, while placing a resistor to ground
will lower the output level (see Figure 7 on Page 3).
5
ANT
6
GND
7
VCC
6
GND
50-ohm RF Output
Analog Ground
Supply Voltage
Analog Ground
Page 4
MODULE DESCRIPTION
The LC Series transmitter is a low-cost, high-performance Surface Acoustic
Wave (SAW) based Carrier-Present Carrier-Absent (CPCA) transmitter capable
of sending serial data at up to 5,000bps. The LC’s compact surface-mount
package integrates easily into existing designs and is equally friendly to
prototype and volume production. The LC’s ultra-low power consumption makes
it ideally suited for battery-powered products. When combined with a Linx LC or
LR Series receiver, a reliable RF link is formed, capable of transferring data over
line-of-sight distances in excess of 300 feet (with the LC Series receiver) or up
to 3,000 feet (with the LR Series receiver).
50Ω RF OUT
(ANT)
Keyed Output
SAW
Oscillator
Vcc
Data In
300-5,000bps
Output Isolation
& Filter
RF Amplifier
Figure 9: LC Series Transmitter Block Diagram
THEORY OF OPERATION
The LC Series transmitter transmits data using Carrier-Present Carrier-Absent
(CPCA) modulation. This type of AM modulation is often referred to by other
designations, including Continuous Wave (CW) and On-Off Key (OOK). This
type of modulation represents a logic low ‘0’ by the absence of a carrier and a
logic high ‘1’ by the presence of a carrier. This method affords numerous
benefits. Three of the most important are:
1) Cost-effectiveness due to design simplicity.
2) No minimum data rate or mark / space ratio requirement.
3) Higher output power and thus greater range in countries (such as the U.S.)
where output power measurements are averaged over time. (Please refer to Linx
Application Note AN-00130).
The LC Series transmitter is based on a simple but highly optimized architecture
that achieves a high fundamental output power with low harmonic content. This
ensures that approval requirements can be met without external filter
components. The LC Series transmitter is exceptionally stable over time,
temperature, and physical shock as a result of the precision Surface Acoustic
Wave (SAW) frequency reference. Due to the accuracy of the SAW device, most
of the output power is concentrated in a narrow bandwidth. This allows the
receiver’s bandwidth to be quite narrow, thus increasing sensitivity and reducing
susceptibility to near-band interference. The quality of components and overall
architecture utilized in the LC Series is extraordinary in a low-cost RF device and
is one reason the LC transmitter is able to outperform more expensive products.
Page 5
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