User's Manual

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Ordering Information
Part Number Description
OTX-***-HH-KF#-MS-xxx MS Keyfob Transmitter
MDEV-***-HH-KF#-MS MS Keyfob Development System
*** = 315, 418 (Standard) or 433.92MHz
xxx = Color (Leave blank for standard black)
WHT = White
CRE = Red
CGY = Gray
Keyfob Electrical Specifications
Parameter Designation Min. Typ. Max. Units Notes
Power Supply
Operating Voltage V
CC
2.1 3.0 3.6 VDC
Supply Current l
CC
3.4 mA
Power-Down Current l
PDN
5.0 nA 1
Transmitter Section
Transmit Frequency Range F
C
OTX-315-HH-KF#-MS 315 MHz
OTX-418-HH-KF#-MS 418 MHz
OTX-433-HH-KF#-MS 433.92 MHz
Center Frequency Accuracy –50 +50 kHz
Data Rate 9,600 bps
Environmental
Operating Temperature Range –40 +85 °C 1
1. Characterized, but not tested
Electrical Specications
Ordering Information
Figure 3: Ordering Information
Figure 4: Electrical Specifications
Theory of Operation
The MS Series Keyfob Transmitter combines a high-performance
synthesized transmitter with an on-board MS Series encoder IC to form
a highly reliable, yet cost-effective RF remote control transmitter. The
transmitter’s advanced synthesized architecture delivers superior stability
and frequency accuracy while minimizing the effects of temperature and
body proximity.
The advanced MS Series encoder has several advantages over previous
solutions. It provides more security by offering 2
24
addresses, which is
several orders of magnitude greater than older encoders. Furthermore,
the address is instantly established with a simple button press, eliminating
cumbersome DIP switches and cut traces. When paired with a MS Series
decoder, keyfob identity can be determined and distinct transmitter-receiver
relationships established.
The Keyfob operates in the following manner: when a button is pressed
on the Keyfob, power is applied to the internal circuitry and the encoder IC
is enabled. The encoder then detects the logic states of the button data
lines. The encoder data is used to modulate the transmitter, which, through
the antenna, conveys the data into free space. The transmission cycle
continues until the button is released. On the receiver side, an MS Series
decoder IC is used to check the transmitter’s address bits against the
address saved in memory. If a match is confirmed, and if the decoder has
permission to recognize the specific button being pressed, the decoder’s
outputs are set to replicate the transmitter’s button states. These outputs
can then be used to activate external circuitry required by the application.
The transmitter is compatible with the LT and LR product families. When
the Keyfob transmitter is combined with an LR Series receiver and MS
Series decoder, ranges of up to 750 feet are possible. Applications
operating over shorter distances will also benefit from the increased link
reliability and superior noise immunity provided by the LR receiver.