Page 5

Page 4

PIN ASSIGNMENTS

GND

DATA

GND

GND

ANT

LADJ/GND

GND

VCC

1

2

3

4

5

6

7

8

Figure 8: LC Series Transmitter Pinout (Top View)

Pin #

Name

Description

1

GND

Analog Ground

2

DATA

Digital Data Input

3

GND

Analog Ground

4

LADJ/GND

Level Adjust. This line can be used to adjust the output

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

50-ohm RF Output

6

GND

Analog Ground

7

Supply Voltage

6

GND

Analog Ground

PIN DESCRIPTIONS

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).

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.

Output Isolation

& Filter

RF Amplifier

Keyed Output

Vcc

SAW

Oscillator

Data In

300-5,000bps

50

Ω RF OUT

(ANT)

Figure 9: LC Series Transmitter Block Diagram