HIGH-PERFORMANCE
RF MODULE
TXM-900-HP3-xxx
WIRELESS MADE SIMPLE
®
HP3 SERIES TRANSMITTER MODULE DATA GUIDE
DESCRIPTION
The HP3 RF transmitter module is the third
generation of the popular HP Series. Like its
0.680"
predecessors, the HP3 is designed for the cost-
effective, high-performance wireless transfer of
analog or digital information in the popular 902-
0.178"
928MHz band. HP3 Series parts feature eight
SIP Style
parallel selectable channels, and some versions
1.260"
also add direct serial selection of 100 channels.
To ensure reliable performance, the transmitter
0.628"
employs FM / FSK modulation and a micro-
processor controlled synthesized architecture.
0.150"
Both SMD and pinned packages are available.
SMD Style
When paired with an HP3 receiver, a reliable
Figure 1: Package Dimensions
link is created for the transfer of analog and
digital information up to 1,000 feet. As with all Linx modules, the HP3 requires no
tuning or additional RF components (except an antenna), making integration
straightforward, even for engineers without prior RF experience.
HP SERIES RF TRANSMITTER
TXM-900-HP3-SP*
LOT 10000
Pin Spacing: 0.1"
HP SERIES RF TRANSMITTER
TXM-900-HP3-SP*
LOT 10000
1.290"
FEATURES
APPLICATIONS INCLUDE
8 parallel, 100 serial (PS Versions) user-
Wireless Networks / Data Transfer
selectable channels
Wireless Analog / Audio
FM / FSK modulation for outstanding
Home / Industrial Automation
performance and noise immunity
Remote Access / Control
Precision frequency synthesized
Remote Monitoring / Telemetry
architecture
Long-Range RFID
Transparent analog / digital interface
MIDI Links
Wide-range analog capability including
audio (50Hz to 28kHz)
Voice / Music / Intercom Links
Wide temperature range
(-30°C to +85°C)
ORDERING INFORMATION
No external RF
PART #
DESCRIPTION
components required
HP3 Transmitter (SIP 8 CH only)
Compatible with previous
TXM-900-HP3-PPO
HP Series modules
TXM-900-HP3-PPS
HP3 Transmitter (SIP 8p / 100s CH)
Power-down and CTS
TXM-900-HP3-SPO
HP3 Transmitter (SMD 8 CH only)
functions
TXM-900-HP3-SPS
HP3 Transmitter (SMD 8p / 100s CH)
Wide supply range
MDEV-900-HP3-PPS-USB
HP3 Development Kit (SIP Pkg.)
(2.8 to 13.0VDC)
MDEV-900-HP3-PPS-RS232
HP3 Development Kit (SIP Pkg.)
High data rate
MDEV-900-HP3-SPS-USB
HP3 Development Kit (SMD Pkg.)
(up to 56kbps)
MDEV-900-HP3-SPS-RS232
HP3 Development Kit (SMD Pkg.)
Pinned and SMD packages
Transmitters are supplied in tubes of 15 pcs.
No production tuning
Revised 1/28/08
ELECTRICAL SPECIFICATIONS
Parameter
POWER SUPPLY
Operating Voltage
Supply Current
Power-Down Current
TRANSMIT SECTION
Transmit Frequency Range
Center Frequency Accuracy
Available Channels
Channel Spacing
Occupied Bandwidth
Output Power
Spurious Emissions
Harmonic Emissions
Data Rate
Analog / Audio Bandwidth
Data Input:
Logic Low
Logic High
Data Input Impedance
Frequency Deviation @ 3VDC
Frequency Deviation @ 5VDC
ANTENNA PORT
RF Output Impedance
TIMING
Transmitter Turn-On Time
Channel Change Time
ENVIRONMENTAL
Operating Temperature Range
–
-30
–
+85
–
–
–
–
7.0
1.0
10.0
1.5
mSec
mSec
–
–
R
OUT
–
50
–
Ω
–
–
–
–
–
–
0.0
2.8
–
60
90
–
–
200
70
115
0.5
5.2
–
110
140
VDC
VDC
kΩ
kHz
kHz
–
–
–
8
8
F
C
–
–
–
–
P
O
–
P
H
–
–
902.62
-50
8 (Par.)
–
–
-3
–
–
100
50
–
–
–
250
115
0
-45
-60
–
–
927.62
+50
100 (Ser.)
–
140
+3
–
-47
56,000
28,000
MHz
kHz
–
kHz
kHz
dBm
dBm
dBm
bps
Hz
3
–
4
–
–
5
6
6
7
7
V
CC
I
CC
I
PDN
2.8
–
–
3.0
14.0
–
13.0
17.0
15.0
VDC
mA
µA
–
1
2
Designation
Min.
Typical
Max.
Units
Notes
ABSOLUTE MAXIMUM RATINGS
Supply Voltage V
CC
Any Input or Output Pin
Operating Temperature
Storage Temperature
Soldering Temperature
-0.3
-0.3
-30
-45
+260°C
to
+18.0
to
V
CC
to
+85
to
+85
for 10 seconds
VDC
VDC
°C
°C
*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 5.0VDC 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.
GND
ANT
GND
NC
CS0
CS1 / SS CLOCK
CS2 / SS D
CTS
PDN
VCC
MODE
DATA
NC
NC
NC
NC
GND
NC
NC
NC
NC
NC
NC
GND
PC
PC
PC
5VDC
PC
Figure 2: Test / Basic Application Circuit
TYPICAL PERFORMANCE GRAPHS
V
CC
/ PDN
V
CC
/ PDN
°
C
–
Table 1: HP3 Series Transmitter Specifications
Notes
1.
2.
3.
4.
5.
6.
7.
Over the entire operating voltage range.
With the PDN pin low.
Serial Mode.
100 serial channels on the PS versions only.
Does not change over the 3-13VDC supply.
Into 50 ohms.
The receiver will not reliably hold a DC level. See the HP3 Series Receiver Module Data Guide for the
minimum transition rate.
8. The voltage specified is the modulation pin voltage.
1
1
RX DATA
CTS
2
CH1 1.00V
CH2 2.00V
2.5mS
Delta 7.200mS
2
CH1 1.00V
CH2 2.00V
2.5mS
Delta 7.200mS
Figure 3: Power-Up to CTS
Figure 4: TX Powerup to Valid RX Data
IN
IN
*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.
OUT
OUT
CH1 2.00V
CH2 500mV
250μS
CH1 2.00V
CH2 500mV
250μS
Figure 5: Sine Wave Modulation Linearity
Page 2
Figure 6: Square Wave Modulation Linearity
Page 3
PIN ASSIGNMENTS
Pinned Transmitter
3 CS0
4 CS1 / SS CLOCK
5 CS 2 / SS DATA
6 CTS
PIN DESCRIPTIONS
Surface-Mount Transmitter
1
2
3
4
5
6
7
8
9
10
11
12
GND
ANT
GND
NC
CS0
CS1 / SS CLOCK
CS2 / SS DATA
CTS
PDN
VCC
MODE
DATA
NC
NC
NC
NC
GND
NC
NC
NC
NC
NC
NC
GND
24
23
22
21
20
19
18
17
16
15
14
13
Pin #
SMD Pinned
1, 3
13, 20
1
Name
GND
Equivalent Circuit
Description
Analog Ground
9
MODE
10 DATA
1 GND
2 ANT
7 PDN
8 VCC
2
2
ANT
RF
Out
50Ω
50-ohm RF Output
5
3
CS0
CS0
25k
Channel Select 0
µ
Channel Select 1 /
Serial Select Clock
Channel Select 2 /
Serial Select Data
Figure 7: HP3 Series Receiver Pinout
Pin #
SMD SIP
1
2
3
4
5
6
3
4
1
2
6
4
CS1 /
SS CLOCK
25k
Name
GND
ANT
GND
NC
CS0
CS1 / SS
CLOCK
CS2 / SS
DATA
CTS
Description
Analog Ground
50-ohm RF Output
Analog Ground (SMD only)
No Electrical Connection. Soldered for physical support
only.
Channel Select 0
Channel Select 1 / Serial Select Clock. Channel Select 1
when in parallel channel selection mode, clock input for
serial channel selection mode.
Channel Select 2 / Serial Select Data. Channel Select 2
when in parallel channel selection mode, data input for
serial channel selection mode.
Clear-To-Send. This line will go high when the transmitter
is ready to accept data.
Power Down. Pulling this line low will place the receiver
into a low-current state. The module will not be able to
receive a signal in this state.
Supply Voltage
Mode Select. GND for parallel channel selection, V
CC
for
serial channel selection
Digital / Analog Data Input. This line will output the
demodulated digital data.
Analog Ground (SMD only)
No Electrical Connection. Soldered for physical support
only. (SMD only)
8
6
CTS
7
5
CS2 /
SS DATA
CS1
µ
25k
CS2
µ
CTS
Out
Clear-to-Send
Output
V
CC
430k
9
7
PDN
PDN
Power Down
(Active Low)
7
5
8
6
10
8
V
CC
Voltage Input 2.8-13V
9
10
11
12
13, 20
14-19,
21-24
Page 4
7
8
9
10
PDN
V
CC
MODE
DATA
GND
NC
11
9
MODE
MODE
160k
25k
Mode Select
µ
100k
12
10
DATA
510k
20pF
Digital / Analog Input
4,
14-19,
21-24
NC
SMD (Only)
No Electrical Connection
Figure 8: Pin Functions and Equivalent Circuits
Page 5
THEORY OF OPERATION
The HP3 Series transmitter is a high-performance, multi-channel RF transmitter
capable of transmitting both analog (FM) and digital (FSK) information. FM / FSK
modulation offers significant advantages over AM or OOK modulation methods,
including increased noise immunity and the receiver’s ability to capture in the
presence of multiple signals. This is especially helpful in crowded bands, such
as the one in which the HP3 operates.
DATA
IN
28kHz Low Pass
Filter
Modulator
12MHz
Crystal
POWER-UP SEQUENCE
The HP3 transmitter is controlled by an
on-board microprocessor. When power is
applied, a start-up sequence is initiated.
At the end of the start-up sequence, the
transmitter is ready to transmit data.
The adjacent figure shows the start-up
sequence. It is executed when power is
applied to the V
CC
line or when the PDN
line is taken high.
POWER ON
Parallel Mode
Determine Mode
Serial Mode
Read Channel-
Selection Inputs
Program Freq. Synth
To Default CH. 50
Program Frequency
Synthesizer
Crystal Oscillator
Begins to Operate
MODE
CS0
CS1
CS2
μP
4MHz
Int. Osc.
PLL
Amplifier
VCO
Band Pass
Filter
RF OUT
Figure 9: HP-3 Series Transmitter Block Diagram
A precision 12.00MHz Voltage Controlled Crystal Oscillator (VCXO) serves as
the frequency reference for the transmitter. Incoming data is filtered to limit the
bandwidth, and then used to directly modulate the reference. Direct reference
modulation inside the loop bandwidth provides fast start-up, while allowing a
wide modulation bandwidth and near DC modulation capability. This also
eliminates the need for code balancing.
The modulated 12.00MHz reference frequency is applied to the Phase-Locked
Loop (PLL). The PLL, combined with a 902 to 928MHz VCXO, forms a frequency
synthesizer that can be programmed to oscillate at the desired transmit
frequency. An on-board microcontroller manages the PLL programming and
greatly simplifies user interface. The microcontroller reads the channel selection
lines and programs the on-board synthesizer. This frees the designer from
complex programming requirements and allows for manual or software channel
selection. The microcontroller also monitors the status of the PLL and indicates
when the transmitter is ready to transmit data by pulling the CTS line high.
The PLL-locked carrier is amplified to increase the output power of the
transmitter and to isolate the VCO from the antenna. The output of the buffer
amplifier is connected to a filter network, which suppresses harmonic emissions.
Finally, the signal reaches the single-ended antenna port, which is matched to
50 ohms to support commonly available antennas, such as those from Linx.
Serial Data Input
Begins to Operate
On power-up, the microprocessor reads
the external channel-selection lines and
Program Frequency
sets the frequency synthesizer to the
Determine State of
Synthesizer
CTS Output Line
appropriate channel. When the frequency
Determine State of
synthesizer has locked on to the proper
CTS Output Line
Cycle Here Until
channel frequency, the circuit is ready to
Channel
or Mode Change
accept data. This is acknowledged by the
Cycle Here Until More
Data Input, Mode Change,
CTS line transitioning high. The module
or PLL Loses Lock
will then transmit data from the user’s
circuit.
Figure 10: Start-up Sequence
Crystal Oscillator
Ready for
POWER SUPPLY
The HP3 incorporates a precision, low-dropout
regulator on-board, which allows operation over an
input voltage range of 2.8 to 13 volts DC. Despite this
regulator, it is still important to provide a supply that is
free of noise. Power supply noise can significantly
affect the transmitter modulation; therefore, providing
a clean power supply for the module should be a high
priority during design.
Vcc TO
MODULE
10Ω
Vcc IN
+
10μF
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 supply power is poor. This filter should be placed close to the module’s supply
lines. These values may need to be adjusted depending on the noise present on
the supply line.
Figure 11: Supply Filter
USING THE PDN PIN
The Power Down (PDN) line can be used to power down the transmitter without
the need for an external switch. This line has an internal pull-up, so when it is
held high or simply left floating, the module will be active.
When the PDN line is pulled to ground, the transmitter will enter into a low-
current (<15µA) power-down mode. During this time, the transmitter is off and
cannot perform any function.
The PDN line allows easy control of the transmitter state from external
components, such as a microcontroller. By periodically activating the transmitter,
sending data, then powering down, the transmitter’s average current
consumption can be greatly reduced, saving power in battery-operated
applications.
Page 7
CTS OUTPUT
The Clear-To-Send (CTS) output goes high to indicate that the transmitter PLL
is locked and the module is ready to accept data. In a typical application, a
microcontroller will raise the PDN line high and begin to monitor the CTS line.
When the line goes high, the microcontroller will start sending data. It is not
necessary to use the CTS output, but if not used, the circuit should wait a
minimum of 10mS after raising the PDN line high before transmitting data. If data
is being sent redundantly, there is generally no need to monitor the CTS line or
to wait a fixed time, though the initial bits may not get through.
Page 6
ADJUSTING THE OUTPUT POWER
Depending on the type of antenna being used, the output power of the
transmitter may be higher than FCC regulations allow. It is intentionally set high
to compensate for losses resulting from inefficient antennas. Since attenuation is
often required, it is generally wise to provide for its implementation so that the
FCC test lab can easily attenuate the transmitter to the maximum legal limit.
A T-pad is a network of three
resistors that allows for variable
attenuation while maintaining the
correct match to the antenna. An
example layout is shown in the
adjacent figure. For more details
on T-pad attenuators, please
see Application Note AN-00150.
TIMING CONSIDERATIONS
Timing plays a key role in link reliability, especially when the modules are being
rapidly turned on and off or hopping channels. Unlike a wire, allowance must be
made for the programming and settling times of both the transmitter and
receiver, or portions of the signal will be lost. There are two major timing
considerations the engineer must consider when designing with the HP3 Series
transmitter. These are shown in the table below. The stated timing parameters
assume a stable supply of 2.8 volts or greater. They do not include the charging
times of external capacitance on the module’s supply lines, the overhead of
external software execution, or power supply rise times.
Parameter
T1
T2
Description
Transmitter turn-on time
Channel change time (time to valid data)
Max.
10.0mS
1.5mS
RF
MODULE
R1
R1 ANTENNA
R2
GROUND PLANE
ON LOWER LAYER
GROUND
Figure 12: T-Pad Attenuator Example Layout
INPUTTING DIGITAL DATA
The DATA line may be directly connected to virtually any digital peripheral,
including microcontrollers, encoders, and UARTs. It has an impedance of 200kΩ
and can be used with any data that transitions from 0V to a 3 to 5V peak
amplitude within the specified data rate of the module. While it is possible to send
data at higher rates, the internal filter will cause severe roll off and attenuation.
Many RF products require a fixed data rate or place tight constraints on the mark
/ space ratio of the data being sent. The HP3 transmitter architecture eliminates
such considerations and allows virtually any signal, including PWM, Manchester,
and NRZ data, to be sent at rates from 100bps to 56kbps.
The HP3 does not encode or packetize the data in any manner. This
transparency gives the designer great freedom in software and protocol
development. A designer may also find creative ways to utilize the ability of the
transmitter to accept both digital and analog signals. For example, an application
might transmit voice, then send out a digital control command. Such mixed mode
systems can greatly enhance the function and versatility of many products.
T1 is the maximum time required for the transmitter to power-up and lock on-
channel. This time is measured from the application of V
CC
to the CTS line
transitioning high.
T2 is the worst-case time needed for a powered-up module to switch between
channels after a valid channel selection. This time does not include external
overhead for loading a desired channel in Serial Channel Select Mode.
Normally, the transmitter will be turned off after each transmission. This is
courteous use of the airwaves and reduces power consumption. The transmitter
may be shut down by switching its supply or the PDN line. When the transmitter
is again powered up, allowance must be made for the requirements above.
In many cases, the transmitter will lock more quickly than the times indicated.
When turn-around time or power consumption are critical, the CTS line can be
monitored so data may be sent immediately upon transmitter readiness.
TRANSMITTING DATA
Once an RF link has been established, the challenge becomes how to effectively
transfer data across it. While a properly designed RF link provides reliable data
transfer under most conditions, there are still distinct differences from a wired link
that must be addressed. Since the modules do not incorporate internal encoding
or decoding, the user has tremendous flexibility in how data is handled.
It is important to separate the types of transmissions that are technically possible
from those that are legally allowed in the country of operation. Application Notes
AN-00126, AN-00140 and Part 15, Section 249 of the FCC rules should be
reviewed for details on acceptable transmission content in the U.S.
If you want to transfer simple control or status signals (such as button presses)
and your product does not have a microprocessor or you wish to avoid protocol
development, consider using an encoder / decoder IC set. These chips are
available from several manufacturers, including Linx. They take care of all
encoding and decoding functions and provide a number of data lines to which
switches can be directly connected. Address bits are usually provided for
security and to allow the addressing of multiple receivers independently. These
ICs are an excellent way to bring basic remote control products to market quickly
and inexpensively. It is also a simple task to interface with inexpensive
microprocessors or one of many IR, remote control, DTMF, or modem ICs.
Page 9
INPUTTING ANALOG SIGNALS
Analog signals from 50Hz to 28kHz may be connected directly to the
transmitter’s DATA line. The HP3 is a single supply device and, as such, is not
capable of operating in the negative voltage range. Analog sources should be
within 0 to 5V
P-P
and should, in most cases, be AC-coupled into the DATA line
to achieve the best performance. The size of the coupling capacitor should be
large enough to ensure the passage of all desired frequencies and small enough
to allow the start-up time desired. Since the modulation voltage applied to the
DATA line determines the carrier deviation, distortion can occur if the DATA line
is over-driven. The actual level of the input waveform should be adjusted to
achieve optimum in-circuit results for your application.
The HP3 is capable of providing audio quality comparable to a radio or intercom.
In applications where higher quality audio is required, a compandor may be
employed to increase dynamic range and reduce noise. If true high-fidelity audio
is required, the HP3 is probably not the best choice, as it is optimized for data.
Page 8
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