TRM-315-LT
TRM-418-LT
TRM-433-LT
WIRELESS MADE SIMPLE
®
LT SERIES TRANSCEIVER MODULE DATA GUIDE
DESCRIPTION
The LT Series transceiver is ideal for the bi-
0.619"
directional wireless transfer of serial data, control, or
command information in the favorable 260-470MHz
band. The transceiver is capable of generating
+10dBm into a 50-ohm load and achieves an
0.630"
RF MODULE
TRM-433-LT
outstanding typical sensitivity of -112dBm. Its
LOT 10000
advanced synthesized architecture delivers
outstanding stability and frequency accuracy, and
minimizes the effects of antenna pulling. When
paired, the transceivers form a reliable wireless link
0.125"
that is capable of transferring data at rates of up to
10,000bps over distances of up to 3,000 feet.
Applications operating over shorter distances or at
Figure 1: Package Dimensions
lower data rates will also benefit from increased link reliability and superior noise
immunity. Housed in a tiny reflow-compatible SMD package, the transceiver requires
no external RF components (except an antenna), which greatly simplifies integration
and lowers assembly costs.
FEATURES
Long range
Low cost
PLL-synthesized architecture
Direct serial interface
Data rates to 10,000bps
No external RF components required
Low power consumption
Compact surface-mount package
Wide temperature range
RSSI and power-down functions
No production tuning
Easy to use
APPLICATIONS INCLUDE
2-Way Remote Control
Keyless Entry
Garage / Gate Openers
Lighting Control
Medical Monitoring / Call Systems
Remote Industrial Monitoring
Periodic Data Transfer
Home / Industrial Automation
Fire / Security Alarms / Access Control
Remote Status / Position Sensing
Long-Range RFID
Wire Elimination
ORDERING INFORMATION
PART #
DESCRIPTION
TRM-315-LT
Transceiver 315MHz
TRM-418-LT
Transceiver 418MHz
TRM-433-LT
Transceiver 433MHz
EVAL-***-LT
Basic Evaluation Kit
*** = Frequency
Transceivers are supplied in tubes of 33 pcs.
Revised 2/28/08
ELECTRICAL SPECIFICATIONS
Parameter
POWER SUPPLY
Operating Voltage
Supply Current
Transmit Mode Logic High
Transmit Mode Logic High
Transmit Mode Logic Low
Receive Mode
Power Down Current
DATA Line:
Output Low Voltage
Output High Voltage
Input Low Threshold
Input High Threshold
Power Down Input:
Input Low Threshold
Input High Threshold
RF SECTION
Frequency Range:
TRM-315-LT
TRM-418-LT
TRM-433-LT
Center Frequency Accuracy
Data Rate
RECEIVER SECTION
LO Feedthrough
IF Frequency
Noise Bandwidth
Receiver Sensitivity
RSSI / Analog:
Dynamic Range
Analog Bandwidth
Gain
Voltage with No Carrier
TRANSMITTER SECTION
Output Power
With a 750Ω resistor on LADJ
Output Power Control Range
Harmonic Emissions
ANTENNA PORT
RF Input Impedance
TIMING
Receiver Turn-On Time:
Via V
CC
Via PDN
Max. Time Between Transitions
Transmitter Turn-On Time:
Via V
CC
Via PDN
Modulation Delay
Transmit to Receive Switch Time
Receive to Transmit Switch Time
Dwell Time
ENVIRONMENTAL
Operating Temperature Range
Page 2
Designation
V
CC
I
CC
Min.
2.1
–
–
–
–
–
–
–
–
0.9V
CC
–
0.9V
CC
Typical
3.0
12
7.6
4.0
6.1
11.5
0.15
V
CC
-0.26
–
–
–
–
Max.
3.6
14
9.5
5.0
7.9
20.0
–
–
0.1V
CC
–
0.1V
CC
–
Units
VDC
mA
mA
mA
mA
µA
VDC
VDC
VDC
VDC
VDC
VDC
Notes
–
1
2
–
–
9,10
3
4
5
–
5
–
ELECTRICAL SPECIFICATIONS
Notes
1. With a 0Ω resistor on LADJ.
2. With a 750Ω resistor on LADJ.
3. I
SINK
= 500µA.
4. I
SOURCE
= 500µA.
5. I
SINK
= 20µA.
6. Into a 50-ohm load.
7. With a 50% square wave at 1,000bps.
8. Time to valid data output.
9. Characterized, but not tested.
10. Receive Mode on power down (see Using the PDN Line section)
11. Minimum time before mode change.
I
PDN
V
OL
V
OH
V
IL
V
IH
V
IL
V
IH
F
C
ABSOLUTE MAXIMUM RATINGS
Supply Voltage V
CC
Any Input or Output Pin
RF Input
Operating Temperature
Storage Temperature
Soldering Temperature
-0.3
-0.3
to
+4.0
to V
CC
+0.3
0
-40
to
+85
-65
to
+150
+260°C for 10 seconds
VDC
VDC
dBm
°C
°C
–
–
–
F
IF
N
3DB
–
–
–
–
–
P
O
P
O
–
P
H
R
IN
–
–
–
-50
65
–
–
–
-108
–
20
–
–
–
-4
-30
-36
–
315
418
433.92
–
–
-80
10.7
280
-112
80
–
15
430
+9.2
0.0
–
–
50
–
–
–
+50
10,000
–
–
–
-118
–
5,000
–
–
+11
+4
MAX
–
–
MHz
MHz
MHz
kHz
bps
dBm
MHz
kHz
dBm
dB
Hz
mV / dB
mV
dBm
dBm
dB
dBc
Ω
–
–
–
–
–
6,9
9
9
7
9
9
9
9
1,6
2,6
9
6
9
*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. The pins marked NC
have no electrical connection.
VCC
1
LADJ
ANT
VCC
GND
NC
GND
RSSI
PDN
A REF
T/R
SEL
ANALOG
DATA
750
Figure 2: Test / Basic Application Circuit
–
–
–
–
–
–
–
–
–
–
–
–
–
–
290
-40
2.2
0.25
15.0
2.0
–
–
180
490
–
–
–
–
–
–
500
30.0
400
1000
–
+85
mSec
mSec
mSec
mSec
µSec
nS
µSec
µSec
µSec
8,9
8,9
9
9
9
9
9
9
9,11
9
*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.
–
°
C
Table 1: LT Series Transceiver Electrical Specifications
Page 3
TYPICAL PERFORMANCE GRAPHS
10
16
9
14
8
12
TYPICAL PERFORMANCE GRAPHS
1. 1.00V/div
2. 2.00V/div
LADJ Resistance (kΩ)
7
Supply
Current (mA)
VCC
10
6
2
8
5
4
6
3
4
2
2
1
DATA
10
8
6
4
2
0
-2
-4
-6
-8
-10
-12
-14
1
0
12.00
9.00
6.00
3.00
0.00
-3.00
-6.00
-9.00
-12.00
-15.00
-18.00
-21.00
0
Output Power (dBm)
Output Power (dBm)
2.00mS/div
Figure 3: Output Power vs. LADJ Resistance
1.6
Figure 4: Output
Consumption
18.00
Power
vs
Current
Figure 9: RX Turn-On Time from V
CC
1. 1.00V/div
2. 2.00V/div
1.4
16.00
1.2
14.00
Supply
Current (mA)
12.00
PDN
2
TX Icc
RX Icc
VRSSI (V)
1
10.00
0.8
8.00
0.6
6.00
0.4
4.00
0.2
DATA
3.50
3.40
3.30
3.20
3.10
3.00
2.90
2.80
2.70
2.60
2.50
2.40
2.30
2.20
2.10
2.00
1
0
-115
-110
-105
-100
-95
-90
-85
-80
-75
-70
-65
-60
-55
-50
-45
-40
-35
-30
0.00
3.60
RF IN (dBm)
Supply
Voltage (V) [LADJ = 0]
500µS/div
Figure 5: RSSI Curve
1. 1.00V/div
2. 2.00V/div
Figure 6: Current Consumption vs. Supply
Figure 10: RX Turn-On Time from PDN
1. 100mV/div
T/R
SEL
RFIN <-35dBm
2
NO RFIN
Carrier
1
200µS/div
500µS/div
Figure 7: RX to TX Change Time
1. 1.00V/div
2. 2.00V/div
Figure 11: RSSI Response Time
1. 200mV/div
2. 2.00V/div
T/R
SEL
2
DATA
2
Carrier
DATA
1
1.00mS/div
50.0nS/div
1
Figure 8: TX to RX Change Time
Page 4
Figure 12: TX Modulation Delay
Page 5
TYPICAL PERFORMANCE GRAPHS
1. 200mV/div
2. 2.00V/div
PIN ASSIGNMENTS
1
2
3
4
5
6
LADJ
ANT
VCC
GND
NC
GND
RSSI
PDN
A REF
T/R
SEL
ANALOG
DATA
12
11
10
9
8
7
PDN
2
Carrier
1
200µS/div
Figure 13: TX Turn-On Time from PDN
1. 200mV/div
2. 2.00V/div
Figure 16: LT Series Transceiver Pinout (Top View)
PIN DESCRIPTIONS
Pin #
2
Vcc
Name
ANT
GND
NC
RSSI
A REF
ANALOG
DATA
Description
50-ohm RF Port
Analog Ground
No Connection
Received Signal Strength Indicator. This line will supply an
analog voltage proportional to the received signal strength.
Analog RMS (Average) Voltage Reference
Recovered Analog Output
Digital Data Line. This line will output the received data
when in Receive Mode and is the data input when in
Transmit Mode.
Transmit / Receive Select. Pull this line low to place the
transceiver into receive mode. Pull it high to place it into
transmit mode.
Power Down. Pull this line low or leave floating to place the
receiver into a low-current state. The module will not be
able to send or receive a signal in this state. Pull high to
activate the transceiver.
Analog Ground
Supply Voltage
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 VCC will
lower the output level (see Figure 3).
1
2
Carrier
1
3
1.00mS/div
4
2. 2.00V/div
Figure 14: TX Turn-On Time from V
CC
1. 200mV/div
5
6
DATA
2
7
Carrier
1
8
T/R SEL
5.00µS/div
Figure 15: TX Turn-Off Time
MODULE DESCRIPTION
The LT Series transceiver is a low-cost, high-performance synthesized AM /
OOK transceiver, capable of transmitting and receiving serial data at up to
10,000bps over line-of-site distances of up to 3,000 feet. Its exceptional receiver
sensitivity and highly stable transmitter output result in outstanding range
performance. The transceiver is completely self-contained and does not require
any additional RF components (except an antenna). This greatly simplifies the
design process, reduces time to market, and reduces production assembly and
testing costs. The LT is housed in a compact surface-mount package that
integrates easily into existing designs and is equally friendly to prototyping and
volume production. The module’s low power consumption makes it ideal for
battery-powered products.
Page 6
9
PDN
10
11
GND
V
CC
12
LADJ/V
CC
Table 2: LT Series Transceiver Pin Descriptions
Page 7
50Ω RF IN
(Antenna)
Band
Select
Filter
LNA
90°
RSSI
GND
0°
10.7MHz
IF Filter
Data
Slicer
-
Limiter
+
Analog
A REF
RX Data
POWER SUPPLY REQUIREMENTS
∑
RX VCO
PLL
XTAL
Figure 17: LT Series Transceiver Block Diagram
THEORY OF OPERATION
The LT Series transceiver sends and recovers
data by AM or Carrier-Present Carrier-Absent
Data
(CPCA) modulation, also referred to as On-Off
Keying (OOK). This type of modulation
Carrier
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.
Figure 18: CPCA (AM) Modulation
The two most important are: 1) cost-effectiveness due to design simplicity, and
2) higher legally-allowable output power and thus greater range in countries
(such as the U.S.) that average output power measurements over time.
The LT’s receiver chain utilizes an advanced synthesized superheterodyne
architecture and achieves exceptional sensitivity. Transmitted signals enter the
module through a 50-ohm 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 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) which is locked by a Phase-Locked Loop (PLL) frequency
synthesizer referenced to a precision crystal. The mixer stage is a pair of double-
balanced mixers and a unique image rejection circuit, which greatly reduces
susceptibility to interference. The IF frequency is further amplified, filtered, and
demodulated to recover the original signal. The signal is squared by a data slicer
and output on the DATA line.
The LT’s transmitter chain is designed to generate up to 10mW of output power
into a 50-ohm single-ended antenna while suppressing harmonics and spurious
emissions. The transmitter is comprised of a VCO locked by the PLL. The output
of the VCO is amplified and buffered by a power amplifier. The amplifier is
switched by the incoming data to produce a modulated carrier. The internal
digital logic controls a switch that connects the LNA input to ground when in
transmit mode, preventing the transmitter from de-sensitizing the receiver. The
carrier is filtered to attenuate harmonics, and then output on the 50-ohm RF port.
The transceiver’s topology makes the module highly immune to frequency
pulling, mismatch, temperature, and other negative effects common to some low-
cost architectures. The LT Series design and component quality enable it to
outperform many far more expensive transceiver products, making it well-suited
for a wide range of consumer and industrial applications.
Page 8
Figure 19: Supply Filter
USING THE PDN LINE
The Power Down (PDN) line can be used to power down the transceiver without
the need for an external switch. This line has an internal pull-down, so when it
is held low or simply left floating, the module will be inactive.
When the PDN line is pulled to ground, the transceiver will enter into a low-
current (~20µA) power-down mode. During this time the transceiver is off and
cannot perform any function. It may be useful to note that the startup time coming
out of power-down will be slightly less than when applying V
CC
.
The PDN line allows easy control of the receiver state from external components,
such as a microcontroller. By periodically activating the transceiver, sending
data, then powering down, the transceiver’s average current consumption can be
greatly reduced, saving power in battery-operated applications.
Note:
If the T/R SEL line is toggled when the transceiver is powered down, internal logic
will wake up and increase the current consumption to approximately 350µA. When high,
the T/R SEL line will sink approximately 15µA, so the lowest current consumption is
obtained by placing the LT into receive mode before powering down.
USING THE RSSI LINE
The transceiver’s Received Signal Strength Indicator (RSSI) line serves a variety
of functions. This line has a dynamic range of 80dB (typical) and outputs a
voltage proportional to the incoming signal strength. 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. Using RSSI to
determine distance or data validity is not recommended.
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. RSSI 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.
+
PA
TX VCO
Digital
Logic
PDN
T/R
SEL
DATA
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 significantly
Vcc TO
affect the receiver sensitivity; therefore, providing
MODULE
clean power to the module should be a design priority.
10Ω
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 the supply power is poor.
Note that the values may need to be adjusted
depending on the noise present on the supply line.
Vcc IN
10μF
Page 9
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