TXM-900-HP-II Linx Technologies Inc, TXM-900-HP-II Datasheet - Page 6

• Manufacturer Part Number: TXM-900-HP-II
• Description: TRANSMITTER RF 900MHZ 8-CHANNEL
• Manufacturer: Linx Technologies Inc
• Series: HP2r

Specifications of TXM-900-HP-II

• Frequency: 902MHz ~ 928MHz
• Applications: ISM, RKE, Security and Fire Alarms
• Modulation Or Protocol: FM, FSK
• Data Rate - Maximum: 50 kbps
• Power - Output: -3dBm ~ 4dBm
• Data Interface: PCB, Through Hole
• Antenna Connector: Through Hole
• Voltage - Supply: 2.17 V ~ 16 V
• Operating Temperature: 0°C ~ 70°C
• Package / Case: SIP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Features: -
• Memory Size: -
• Current - Transmitting: -
• Other names: TXM-900-HP2; TXM-900-HP2

Page 6
BOARD LAYOUT CONSIDERATIONS
An on-board micro-controller reads the channel-selection lines and programs the
PLL to the desired channel frequency. The micro-controller also monitors the
status of the PLL and indicates when the transmitter is stable and ready to
transmit data by asserting the CTS line high.
A buffer amplifier is used to isolate the VCO from the antenna and to increase
the output power of the transmitter. The output of the buffer amplifier is connected
to a LPF which is used to suppress harmonic emissions. All harm o n i c
specifications are based on a 50-ohm load.
layout requirements. Fortunately, because of the care taken by Linx in the layout
very straightforward.By adhering carefully to a few basic design and layout rules,
A ground-plane (as large as possible) should be placed directly under the HP-II
as reasonably possible, be isolated
P C B.
should be kept as far away as possible
horizontally, it should be laid over so that the side with the crystal is closest to
the user’s PC board and the RF side is facing away from the PC board.
A simple trace is suitable for runs up to 1/8 inch for monopole antennas with wide
bandwidth characteristics. For longer runs or to avoid detuning a narrow
5-6dB above Part 15 limits (assuming the use of a unity antenna).This is done
purposefully to allow designers with less efficient antennas to achieve the
If you are at all familiar with RF devices you may be concerned about specialized
of the module’s PCB, integrating an HP Series-II transmitter into your design is
you can enjoy a trouble-free path to RF success.
transmitter. This ground-plane can also be critical to the performance of your
antenna.
The HP-II transmitter should, as much
from all other components on your
c i r c u i t ry such as crystal oscillators
from the transmitter module.
If the transmitter must be mounted
The trace from the receiver to the antenna should be kept as short as possible.
bandwidth antenna such as a helical, use a 50-ohm coax or 50-ohm microstrip
transmission line as shown in Figure 14.
Observant designers will notice that the output power of the HP Series-II is set
Figure 13A: Attenuation pad layout
S p e c i f i c a l l y,
high-frequency
Figure 13: HP Series-II transmitter footprint
maximum output power allowed by law.
style such as a whip is utilized, it is
often necessary to make provisions for
ex t e rnal attenu a t i o n . This is easily
accomplished by providing pads for a
three-resistor attenuation network as
shown in fig. 13A. The inline pads may
be bridged if the network is not needed.
The resistors should be a surfa c e -
In cases where an efficient antenna