Anaren Integrated Radio
A2500R24x Users Manual
Release Date 01/10/11
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Users Manual
Models A2500R24A and A2500R24C
Contents
1. Overview .............................................................................................................................. 5
1.1. A2500R24A .................................................................................................................... 5
1.2. A2500R24C .................................................................................................................... 5
1.3. Features .......................................................................................................................... 6
1.4. Theory of Operation ........................................................................................................ 6
1.4.1. Typical Flow ............................................................................................................ 9
1.5. Applications .................................................................................................................. 11
2. Product Approvals ............................................................................................................. 12
2.1. USA (Federal Communications Commission, FCC, ) .............................................. 12
2.1.1. FCC Labeling Requirements ................................................................................. 12
2.1.2. End User Manual ................................................................................................... 13
2.1.3. RF Exposure ......................................................................................................... 13
2.2. Canada (Industry Canada, IC) ...................................................................................... 14
2.3. Europe (Conformité Européenne, ) ........................................................................... 15
2.4. Potential Interference Sources...................................................................................... 16
2.4.1. WLAN .................................................................................................................... 16
2.4.2. Bluetooth ............................................................................................................... 16
2.4.3. Microwave ovens ................................................................................................... 16
2.4.4. Other Interference ................................................................................................. 17
2.4.5. Time critical data ................................................................................................... 17
2.5. Approved Usage ........................................................................................................... 17
2.5.1. USA & Canada ...................................................................................................... 17
2.5.2. Europe ................................................................................................................... 18
3. Electrical Characteristics ................................................................................................... 19
3.1. Absolute Maximum Ratings .......................................................................................... 19
3.2. Operating Conditions .................................................................................................... 20
3.3. Pin Out .......................................................................................................................... 20
3.4. Recommended Layout .................................................................................................. 22
3.5. Power Supply Considerations ....................................................................................... 24
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A2500R24x – Users Manual Page 5 of 26
Release Date 01/10/11
1. Overview
The A2500R24C and A2500R24A are surface mount modules with an integrated crystal,
internal voltage regulator, matching circuitry and filtering. The A2500R24A has an integral
antenna, whereas the A2500R24C utilizes an external antenna through a U.FL connector (see
Table 1). The modules operate in the global non-licensed 2.4GHz ISM/SRD frequency band and
are ideal for achieving low power wireless connectivity without having to deal with extensive RF,
antenna design and regulatory compliance, allowing quick time to market. The modules are
100% tested to provide consistent performance.
The A2500R24C and A2500R24A have received regulatory approvals for modular devices in
the United States (FCC), Canada (IC) and Europe (ETSI). The modular approval allows the
OEM or end user to place either an A2500R24A or an A2500R24C with an approved antenna
inside a finished product without having to perform costly regulatory testing for an intentional
radiator. Section 2 has information on the requirements for the end user/integrator must fulfill to
use the modules without intentional radiator regulatory testing.
The A2500R24C and A2500R24A are based on the CC2500 transceiver IC from Texas
Instruments. All control lines for the transceiver are provided at module level for full control of its
operation. Please see the CC2500 data sheet (www.ti.com) for how to control the modules.
Please see section 2.5 for the recommended register settings to achieve optimal performance
and regulatory compliance.
The A2500R24C and A2500R24A modules both measure 9x12x2.5mm and are footprint
compatible with each other.
1.1. A2500R24A
The A2500R24A has an integral antenna, providing high efficiency and near omni-directional
radiation pattern. This approach offers the lowest system cost when the application allows
collocation of radio and antenna.
1.2. A2500R24C
The A2500R24C has a compact antenna connector that allows for locating the antenna away
from the module due to form/function or in order to exit a metal enclosure, see section 3.2 for
more information on antenna location and enclosure considerations.
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1.3. Features
Features:
• Frequency range: 2400 – 2483.5 MHz
• Ultra small package size 9mm x 12mm
x 2mm
• Impedance controlled multi-layer PCB
• Shielded Package
• 1.8 to 3.3 V operation
• SPI Interface
• ROHS Compliant
• LGA Footprint
• Low Power Consumption
• Regulatory approvals for FCC, IC,
ETSI
• Digital RSSI output
• Programmable channel filter bandwidth
• Programmable output power up to +1
dBm
• High sensitivity (–104 dBm at 2.4
kBaud, 1% packet error rate)
• Low current consumption (13.3 mA in
RX, 250 kBaud, input well above
sensitivity limit)
• Separate 64-byte RX and TX data
FIFOs
• Fast startup time: 250us from SLEEP
to Rx or Tx mode
• Data Rate: 1.2 – 500 Kbit/Sec
• Programmable data rate from 1.2 to
500 kBaud
• Sleep state: 0.4mA
• Idle State: 1.5mA
Benefits Summary:
• Operating temperature -40 to +85C
• 100% RF Tested in production
• Common footprint for all family
members
• No RF engineering experience
necessary
• Only requires a 2 layer PCB
implementation
• Excellent receiver selectivity and
blocking Performance
• Suitable for frequency hopping and
multichannel systems due to a fast
settling frequency synthesizer with 90
us settling time
• Suited for systems compliant with EN
300 328 and EN 300 440 class 2
(Europe), FCC CFR47 Part 15.247b
and 15.249 (US)
• No regulatory “Intentional radiator”
testing required to integrate module
into end product. Simple certification
labeling replaces testing.
1.4. Theory of Operation
The A2500R24C and A2500R24A are for low power wireless applications in the 2400MHz to
2483.5MHz global ISM/SRD band. The devices can be used to implement a variety of networks,
including; point to point, point to multipoint, peer to peer and mesh networks
The A2500R24C and A2500R24A both interface to an application microcontroller via an SPI
bus. Physical and MAC layer functionality are accessed via the SPI bus, through addressable
registers as well as execution commands. Data received or to be transmitted are also accessed
through the SPI bus and are implemented as a FIFO register (64 bytes each for Tx and Rx).
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To transmit, a frame of data is placed in the FIFO; this may include a destination address. A
transmit command is given, which will transmit the data according to the initial setup of the
registers. To receive data, a receive command is given, which enables the unit to “listen” for a
transmission and when one occurs put the received frame in the FIFO. When neither transmit or
receive is required the device can enter either an Idle mode, from which it can quickly re-enter
receive, a transmit mode, or a low power sleep mode, from which a crystal startup is also
required prior to transmit or receive operation.
Below a block diagram is given for each of the A2500R24C and A2500R24A modules.
• Antenna
o The antenna couples energy between the air and the AIR module. For
applications where installations are done by an end user (non-professional), an
omni-directional antenna pattern is desired, such that the application will work
equally well in any direction. Similarly for peer to peer or point to multipoint
applications an omni-directional pattern is desired such that all nodes have a fair
chance of communicating. The A2500R24A module has an integral antenna that
is near omni-directional, whereas the A2500R24C has approved antenna options
ranging from near omni-directional to shaped front/back patterns (useful for
inline, professional installations). Note that the end radiation pattern depends not
only on the antenna, but also on the ground plane, enclosure and installation
environment.
• Filtering
o Filtering removes spurious signals to comply with regulatory intentional radiator
requirements.
• Matching
o Matching provides the correct loading of the transmit amplifier to achieve the
highest output power as well as the correct loading for the receive LNA to
achieve the best sensitivity.
• Physical
o The physical layer provides conversions between data, symbol and RF signal.
• MAC
o The MAC layer is part of the Logical Link Layer and provides frame handling,
addressing and medium access services.
• Microcontroller Interface
o The microcontroller interface exposes registers and commands for the physical
and MAC layers to a microcontroller.
• Power Management
o Power management ensures a stable supply for the internal functions as well as
providing means for a low power sleep mode (in which case, most of the
transceiver is power off).
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Figure 1 The functionality of the A2500R24A, using an integral antenna
Figure 2 The functionality of the A2500R24C, using an external antenna.
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Figure 3 Transceiver IC block diagram.
1.4.1. Typical Flow
After initial setup of registers for desired behavior, the normal operation flow diagram is shown
in Figure 4. In applications of infrequent data transmissions the transceiver would be in “sleep”
mode to save power (400nA). From there it would awaken and then enter “idle” mode. As part of
the wake up process the crystal oscillator is started (~250µs) and the digital microcontroller
interface is powered up. Before transmit or receive, the frequency synthesizer needs to be
started (“FS_Wakeup”) and, having been powered off (or idle for a while), the control loop of the
VCO/PLL needs to be calibrated (“calibrate”).
A data frame is loaded into the transmit FIFO and the “TX” mode is entered. The transceiver will
transmit the data and enter “idle” mode after completion. When transmit is complete “RX” mode
is entered to wait for the acknowledge frame. Once a frame is received the transceiver will again
enter “idle”mode. If no acknowledge frame is received within a given timeout the data frame
would be re-transmitted. If the acknowledge frame indicates that the data was received the next
data frame will be transmitted. After the last data frame has been transmitted successfully, the
transceiver will again be put in “sleep” mode.
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Medium access
Figure 4 Transceiver state diagram
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1.5. Applications
Ultra low-power wireless applications, operating in the 2400-2483.5 MHz ISM/SRD bands.
Wireless alarm and security systems
Industrial monitoring and control
Wireless sensor networks
AMR – Automatic Meter Reading
Home and building automation
Wireless game controllers
Wireless audio
Wireless keyboard and mouse
RF enabled remote controls
Existing applications where simple upgrade to wireless is desired
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2. Product Approvals
The A2500R24C and A2500R24A have been designed to meet most national regulations for
world-wide ISM-band use. In particular the radio modules have been certified to the following
standards.
2.1. USA (Federal Communications Commission, FCC, )
The A2500R24A, with integrated antenna, as well as the A2500R24C, used with the antennae
listed in Table 1 below, have been tested to comply with FCC CFR47 Part 15 sub-part C
“Intentional Radiators. The devices meet the requirements for modular transmitter approval as
detailed in FCC public notice DA 00-1407 Released: June 26, 2000. The A2500R24A and
A2500R24C module can be integrated into a finished product with obtaining subsequent FCC
approvals.
(15.19a3) The modules comply with part 15 of the FCC rules. Operation is subject to the
following two conditions: (1) this device may not cause harmful interference, and (2) this device
must accept any interference received, including interference that may cause undesired
operation.
Table 1 Approved Antennae
Item Part Number Manufacturer Type Gain
1 Integral part of A2500R24A Anaren Integral Antenna 2
2 66089-2406 Anaren Monopole whip, 6mm lead 3
3 66089-2430 Anaren Monopole whip, 30mm lead 3
4 66129-2480 Anaren Patch. 80mm lead 5
2.1.1. FCC Labeling Requirements
The A2500R24A and A2500R24C modules have been labeled with their own FCC ID number
and if the FCC ID is not visible when the module is installed inside another device, then the
outside of the finished product into which the module is installed must also display a label
referring to the enclosed module. This exterior label can use wording such as the following:
Anaren
FCC ID: X7J-A10030501
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Contains Transmitter Module FCC ID: X7J-A10030501
-or-
Contains FCC ID: X7J-A10030501
This device complies with Part 15 of the FCC Rules.
Operation is subject to the following two conditions:
(1) this device may not cause harmful interference, and (2) this device must accept any
interference received, including interference that may cause undesired operation.
2.1.2. End User Manual
The end user manual should include the following statement:
This equipment has been tested and found to comply with the limits for a Class B digital device,
pursuant to part 15 of the FCC Rules. These limits are designed to provide reasonable
protection against harmful interference in a residential installation. This equipment generates,
uses and can radiate radio frequency energy and, if not installed and used in accordance with
the instructions, may cause harmful interference to radio communications. However, there is no
guarantee that interference will not occur in a particular installation. If this equipment does
cause harmful interference to radio or television reception, which can be determined by turning
the equipment off and on, the user is encouraged to try to correct the interference by one or
more of the following measures:
• Reorient or relocate the receiving antenna.
• Increase the separation between the equipment and receiver.
• Connect the equipment into an outlet on a circuit different from that to which the receiver
is connected.
• Consult the dealer or an experienced radio/TV technician for help.
2.1.3. RF Exposure
All transmitters regulated by the FCC must comply with RF exposure requirements. OET
Bulletin 65 “Evaluating Compliance with FCC Guidelines for Human Exposure to Radio
Frequency Electromagnetic Fields” provides assistance in determining whether proposed or
existing transmitting facilities, operations or devices comply with limits for human exposure to
Radio Frequency (RF) fields adopted by the Federal Communications Commission (FCC). The
bulletin offers guidelines and suggestions for evaluating compliance.
If appropriate, compliance with exposure guidelines for mobile and unlicensed devices can be
accomplished by the use of warning labels and by providing end users with information
concerning minimum separation distances from transmitting structures and proper installation of
antennas.
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The following statement must be included as a CAUTION statement in manuals and OEM
products to alert end users of FCC RF Exposure compliance:
To satisfy FCC RF Exposure requirements for mobile and base station transmission devices, a
separation distance of 20 cm or more should be maintained between the antenna of this device
and persons during operation. To ensure compliance, operation at closer than this distance is
not recommended. The antenna(s) used for this transmitter must not be co-located or operating
in conjunction with any other antenna or transmitter.
If the A2500R24A and A2500R24C module is used in a portable application (antenna is less
than 20 cm from persons during operation), the end user is responsible for performing Specific
Absorption Rate (SAR) testing in accordance with FCC rules 2.1091.
2.2. Canada (Industry Canada, IC)
The A2500R24A and A2500R24C modules have been certified for use in Canada under
Industry Canada (IC) Radio Standards Specification (RSS) RSS-210 and RSS-Gen.
From section 7.1.1 RSS-Gen, Issue 2, June 2007, Modular Transmitter Approval:
Host devices which contain separately certified modules do not need to be recertified, provided
that they meet the following conditions:
a) The host device, as a stand-alone unit without any separately certified modules, complies
with all applicable Radio Standards Specifications.
b) The host device and all the separately certified modules it contains jointly meet the RF
exposure compliance requirements of RSS-102, if applicable.
c) The host device complies with the certification labeling requirements of each of the modules it
contains.
Note: Compliance of a module in its final configuration is the responsibility of the applicant. A
host device will not be considered certified if the instructions regarding antenna configuration
provided in the original description, of one or more separately certified modules it contains, were
not followed.
From section 5.2, RSS-Gen, Issue 2, June 2007, Equipment Labels: All Category I radio
equipment intended for use in Canada shall permanently display on each transmitter, receiver,
or inseparable combination thereof, the applicant's name (i.e., manufacturer's name, trade
name or brand name), model number and certification number. This information shall be affixed
in such a manner as not to be removable except by destruction or defacement. The size of the
lettering shall be legible without the aid of magnification, but is not required to be larger than 8-
point font size. If the device is too small to meet this condition, the information can be included
in the user manual upon agreement with Industry Canada.
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Label:
Contains IC: 8975A-A10030501
From section 7.1.6, RSS-Gen, Issue 2, June 2007, Digital Circuits: If the device contains digital
circuitry that is not directly associated with the radio transmitter, the device shall also have to
comply with ICES-003, Class A or B as approp riate, except for ICES-003 labeling requirements.
The test data obtained (for the ICES-003 tests) shall be kept by the manufacturer or importer
whose name appears on the equipment label, and made available to Industry Canada on
request, for as long as the model is being marketed in Canada.
For more information see: Industry Canada http://www.ic.gc.ca/
2.3. Europe (Conformité Européenne, )
The A2500R24A and A2500R24C modules have been certified for use in European countries.
The following testing has been completed:
Test standard ETSI EN 300 328 V1.7.1 (2006-10)
• Maximum Transmit Power
• Maximum EIRP Spectral Density
• Frequency Range
• Radiated Emissions
Test standards ETSI EN 301 489-1:2008 and ETSI EN 301 489-17:2008
• Radiated Emissions
• Electro-Static Discharge
• Radiated RF Susceptibility
A helpful document that can be used as a starting point in understanding the use of short range
devices (SRD) in Europe is the European Radio Communications Committee (ERC)
Recommendation 70-03 E, downloadable from the European Radio Communications Office
(ERO) http://www.ero.dk.
The end user is responsible for ensuring compliance with harmonized frequencies and labeling
requirements for each country the end device is marketed and sold.
For more information see:
• Radio And Telecommunications Terminal Equipment (R&TTE)
http://ec.europa.eu/enterprise/rtte/index_en.htm
• European Conference of Postal and Telecommunications Administrations (CEPT)
http://www.cept.org/
• European Telecommunications Standards Institute (ETSI) http://www.etsi.org/
• European Radio Communications Office (ERO) http://www.ero.dk/
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2.4. Potential Interference Sources
The radio modules operate in the unlicensed ISM band, in which there are many other
applications e.g. WLAN, Bluetooth® and microwave ovens. This can cause interference that
may, in certain conditions, prohibit radio communication. The user is encouraged to implement a
number of channels and to alternate between those channels based on one of the below
methods.
• Sense if a particular channel is clear prior to transmitting (clear channel assessment)
• Pseudo Random channel change
• Select channels with the least interference (site survey)
Some of the most common interferences are listed below.
2.4.1. WLAN
Wireless Local Area Networks (WLANs) are divided into a number of overlapping channels.
Figure 5 below shows the channels used by WLAN; for the US and Canada, only channels 1-13
may be used. Predominantly, channels 1, 6 and 11 are used to achieve non-overlapping
channels. The user is therefore encouraged to select a channel scheme that also has channels
falling in between, or entirely outside, WLAN channels. Using a detection scheme (clear channel
assessment) will enable the user to find channels with minimal interference from WLAN devices.
Figure 5 WLAN channels
2.4.2. Bluetooth®
Bluetooth® divides the 2.402-2.480 GHz band into 79 channels, each of which is 1MHz wide.
However, since Bluetooth® changes channels rapidly (up to 1600 times a second), it is unlikely
to cause continuous interference in a specific channel and can be overcome by implementing a
simple acknowledge/retransmit functionality.
2.4.3. Microwave ovens
A typical microwave oven uses a self-oscillating magnetron with a duty cycle below 50%,
because the tube is completely off for half of every AC mains cycle (8.33 ms in 60 Hz countries
and 10 ms in 50 Hz countries). The frequency of the microwave oven changes cyclically within
each AC mains synchronized on period, and is generally not predictable.
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The user is encouraged to have packet transmission durations less than half the AC mains
period and implement an acknowledge/retransmit method.
2.4.4. Other Interference
Systems similar to the user’s system may also exist within range and may also be a source of
interference; some typical applications to consider are:
• Alarm systems
o These typically use low duty cycles and are therefore easy to avoid using
acknowledge/retransmit methods
• Car alarms (internal motion sensors)
• Video surveillance
o These are typically operated on a fixed channel, determined at installation time
and can be avoided by using clear channel assessment. It may be useful to
change the channel used by the video surveillance equipment also, if possible.
2.4.5. Time critical data
If the user requires specific time critical data throughput that cannot tolerate the delays of
potentially many re-transmissions, the user is encouraged to implement an environment-aware
algorithm that periodically monitors/scans the frequency band and maintain a list of “best
available” channels.
2.5. Approved Usage
The radio modules can be used in a variety of physical layer configurations, the following
restricts the use to maintain compliance with the above referenced certification bodies.
The user is encouraged to use minimum power required to establish a link, thus minimizing
interference.
Changes or modifications to the module and/or operation outside the limits set forth below are
prohibited and could void the user’s authority to operate the modules.
Uses of these radio modules are limited to the following frequency ranges and modulation
settings. Using the radio modules outside of these limitations are prohibited and could void the
user’s authority to operate the modules. The user should use one of the register configurations
listed below.
Anaren provides register setting files for optimal performance and compliance for each of the
data rates given in the following at www.anaren.com.
2.5.1. USA & Canada
Within the USA and Canada, the modules have been approved for use as digitally modulated
transmitters, for which they must have a minimum occupied bandwidth (6dB) of 500kHz. In
addition the spectral density may not exceed 8dBm/3kHz and the total output power including
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antenna gain may not exceed 1W. The following table shows configurations that are compliant
with this use and the expected performance.
Expected
Dat a Rate Devi at i on F0m i n F0m ax Max Power Channel Rx F il ter Link Budget
kb/s kHz MHz MHz dBm kHz KHz dB
1.2 140 2401.3 2480.4 1.0 310.242 650.000
2.4 140 2401.3 2480.4 1.0 310.242 650.000
4.8 140 2401.3 2480.4 1.0 310.242 650.000
10 140 2401.3 2480.4 1.0 310.242 650.000
20 140 2401.3 2480.4 1.0 310.242 650.000
40 140 2401.3 2480.4 1.0 310.242 650.000
75 140 2401.3 2480.4 1.0 310.242 650.000
125 140 2401.3 2480.4 1.0 310.242 650.000
250 140 2401.3 2480.4 1.0 310.242 650.000
SuggestedRequirement
In a frequency-agile implementation or an implementation with multiple systems sharing the
same location, using 2FSK or GFSK, the user is encouraged to only use even channel numbers
to avoid overlapping channels (127 channels would thus be available).
Expected
Dat a Rate P hase F0m i n F 0max M ax Power Channel Rx F il ter Li nk Budget
kb/s MHz MHz dBm kHz KHz dB
420 0 2401.8 2480.3 1.0 307.861 812.500
500 0 2401.8 2480.3 1.0 307.861 812.500
MS K Modul a tion
Requirement Suggested
In a frequency agile implementation or an implementation with multiple systems sharing the
same location, using MSK, it is recommended to only use every 3rd or 4th channel to avoid
overlapping channels, 85 or 64 channels would thus be available.
It is encouraged to use a medium access technique which should include addressing of
individual transceiver nodes; and should include a combination of a clear channel assessment,
transmit and detect, or a frequency hopping method. This ensures that the un-licensed band
can be shared with other systems/applications.
2.5.2. Europe
For Europe, the maximum power is 100mW, with a maximum spectral density of 10mW per
MHz; but there is no minimum occupied bandwidth requirement. However, a product that will
ship to both US/Canada and Europe must use the settings for US/Canada.
For Europe a medium access protocol is required. The transceiver module provides the
following medium access services:
• Clear channel assessment
• 8 bit address
• Receive packet qualification (Address, CRC)
• Packetized/Frame handling
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3. Electrical Characteristics
3.1. Absolute Maximum Ratings
Under no circumstances must the absolute maximum ratings given in Table 2 be violated.
Stress exceeding one or more of the limiting values may cause permanent damage to the
device.
Parameter Min Max Unit Condition/Note
Supply Voltage (Vdd) -0.3 3.9 V
Voltage on any digital pin -0.3 Vdd+0.3,
max 3.9 V
RF input power +10 dBm
Storage Temperature -50 150 ˚C
Solder reflow temperature 260 ˚C According to IPC/JEDEC J-
STD-020D
ESD <500 V
A
ccording to JEDEC STD 22,
method A114, Human body
model
ESD 400 V
A
ccording to JEDEC STD 22,
C101C, Charged Device
Model (CDM)
Table 2 Absolute Maximum Ratings
Caution!
ESD sensitive device. Precaution should be
used when handling the device in order to
prevent permanent damage.
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3.2. Operating Conditions
Parameter Min Max Unit Condition/Note
Supply Voltage (Vdd) 1.8 3.6 V
Temperature Range -40 +85 ˚C
3.3. Pin Out
The A2500R24C and A2500R24A radio modules share a common pin-out and foot print, that is
also shared by Anaren modules using other frequencies -- thus enabling easy changeover from
one to another, e.g. if changing the frequency, antenna scheme, or adaptive antenna tuning is
desired. Below the common footprint are shown.
Pin # Pin Name Pin Type Description
1 DNC NC Do Not Connect. Internal GND connection used during
testing, not recommended to connect to main GND.
2 DNC NC Do Not Connect. Internal RF output connection used
during test. Connecting this pin to anything will require
recertification for intentional radiators.
3 DNC NC Do Not Connect. Internal GND connection used during
testing, not recommended to connect to main GND.
4 NC NC No Connect, the pin is not connected internally, but is
reserved for future expansion. It is recommended not to
connect this pin to anything.
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5 NC NC No Connect, the pin is not connected internally, but is
reserved for future expansion. It is recommended not to
connect this pin to anything.
6 NC NC No Connect, the pin is not connected internally, but is
reserved for future expansion. It is recommended not to
connect this pin to anything.
7 Vdcoup1 Analog Optional decoupling of the modules internal Vdd supply. It
is recommended to not connect anything to this pin. In
particular noisy environment this pin can be used to further
reduce the noise on the modules internal Vdd, please see
section 3.4 for further information.
8 GND Ground One of two primary ground pins
9 SCLK Digital
Input SPI bus clock signal
10 MISO/GDO1 Digital
Output SPI bus data out from radio when CSN is low, and general
purpose I/O pin when CSN is high
11 MOSI Digital
Input SPI bus data into radio
12 _CSN Digital
Input SPI bus select (active low)
13 GDO0 Digital I/O
(Analog
output)
General purpose port
14 GDO2 Digital I/O General purpose port
15 Vdcoup2 Analog Optional decoupling of the modules internal Vdd supply. It
is recommended to not connect anything to this pin. In
particular noisy environment this pin can be used to further
reduce the noise on the modules internal Vdd, please see
section 3.4 for further information.
16 NC NC No Connect, the pin is not connected internally, but is
reserved for future expansion. It is recommended not to
connect this pin to anything.
17 GND Ground One of two primary ground pins
18 Vdd Power
Supply Power supply pin
19 NC NC No Connect, the pin is not connected internally, but is
reserved for future expansion. It is recommended not to
connect this pin to anything.
20 NC NC No Connect, the pin is not connected internally, but is
reserved for future expansion. It is recommended not to
connect this pin to anything.
21 NC NC No Connect, the pin is not connected internally, but is
reserved for future expansion. It is recommended not to
connect this pin to anything.
22 DNC NC Do Not Connect. Internal GND connection used during
testing, not recommended to connect to main GND.
23 DNC NC No Connect, the pin is not connected internally, but is
reserved for future expansion. It is recommended not to
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connect this pin to anything.
24 DNC NC Do Not Connect. Internal GND connection used during
testing, not recommended to connect to main GND.
Table 3 Pin Descriptions
3.4. Recommended Layout
Figure 6 Recommended PCB layout.
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Figure 7 Mounting the module in a
corner
Figure 8 Mounting the module along an
edge
Figure 9 Mounting the module along an
edge with overhang. This option is not
generally recommended, but is a
method to save PCB in an
environmentally benign environment
Figure 10 Mounting the module along an
edge, with a ground plane cut-out. This
option degrades range slightly.
Page 24 of 26 A2500R24x – Users Manual
Release Date 01/10/11
3.5. Power Supply Considerations
Noise on the power supply line reduces the sensitivity of a receiver and modulates onto a
transmitters signal, both of which causes a degradation of link quality and hence a reduction in
range.
The A2500R24C and A2500R24A radio modules each have an integral ferrite bead in the
supply line from pin 18 (Vdd) and decoupling capacitance to reduce any noise on the incoming
power supply line. This arrangement will eliminate most supply voltage noise. In particular noisy
environments (switching regulators, motor controls, etc.), it may be necessary to add additional
noise reduction means.
Pin 7 (Vdcoup1) is connected to the modules internal supply line after the ferrite bead and
decoupling capacitors and can be used to probe the noise at module level. The noise level
measured on pin 7 should not exceed 120mVpp when in transmit or receive mode, it may
however exceed this value when setting up or accessing data to/from the FIFO’s while not
actively transmitting or receiving.
If the level measured is exceeding the above limit, steps should be taken to ensure maximum
range, including:
• Adding decoupling capacitance to pin 7 (Vdcoup1).
• Adding additional filtering in the supply line.
• Adding an LDO in the supply line (the TPS731xx low Dropout Regulator from TI is
recommended).
A2500R24x – Users Manual Page 25 of 26
Release Date 01/10/11
HISTORY
Date Author Change Note No./Notes
05/31/10 Richardson Initial Draft
07/15/10 Richardson Initial Release
12/17/10 Richardson Formatting applied – no content change
01/10/11 Richardson Corrected typographic errors
Thank you for learning more about the
Anaren Integrated Radio (AIR) module line.
If you have additional questions,
need samples, or would like a quote –
please do not hesitate to email the AIR team
at AIR@anaren.com or contact any of these
authorized distributors of the AIR product line.
Worldwide North America Worldwide
Anaren Microwave, Inc.
6635 Kirkville Road
East Syracuse, NY 13057
Tel: +1 315 432 8909
+1 800 411 6596
Fax: +1 315 432 8970
Anaren Microwave (Europe), Inc.
12 Somerset House, Suite 16 & 17
Hussar Court, Waterlooville
Hampshire, England P07-7S G
Tel: +44 2392 232392
Fax: +44 2392 251369
A
naren Communication Suzhou Co. Ltd.
No. 5 Chun Hui Road
Wei Ting, Suzhou Industrial Park
Suzhou 215122, PR China
Tel: +86 512 6287 6400
Fax: +86 512 6274 9283
