Anaren A2541R24x User manual

3
Anaren Integrated Radio
A2541R24x User’s Manual
Release Date: 11/22/13

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USER’S MANUAL
Models A2541R24A and A2541R24C
Contents
1. Overview ..........................................................................................................................................................5
1.1. A2541R24A.................................................................................................................................................5
1.2. A2541R24C.................................................................................................................................................6
1.3. Features.......................................................................................................................................................6
1.4. Theory of Operation..................................................................................................................................7
1.5. Applications.............................................................................................................................................10
2. Approvals and Usage ...................................................................................................................................11
2.1. Product Approvals..................................................................................................................................11
2.1.1. USA (Federal Communications Commission, FCC).........................................................................11
2.1.1.1. FCC Labeling Requirements ................................................................................................11
2.1.1.2. End User Manual ...................................................................................................................12
2.1.1.3. RF Exposure............................................................................................................................12
2.1.2. Canada (Industry Canada, IC)..........................................................................................................12
2.1.2.1. IC Labeling Requirements ....................................................................................................14
2.1.2.2. RF Exposure............................................................................................................................16
2.1.3. Europe (Conformité Européenne, )...............................................................................................16
2.1.4. Bluetooth Special Interest Group (SIG) ............................................................................................17
2.2. Potential Interference Sources ...............................................................................................................17
2.2.1. WLAN...............................................................................................................................................17
2.2.2. Classic Bluetooth ...............................................................................................................................18
2.2.3. Microwave ovens...............................................................................................................................18
2.2.4. Other Interference .............................................................................................................................18
2.2.5. Time critical data...............................................................................................................................19
2.3. Approved Usage .....................................................................................................................................20
2.3.1. USA and Canada...............................................................................................................................20
2.3.2. Europe ...............................................................................................................................................21
2.3.3. Bluetooth ...........................................................................................................................................21
3. Electrical Characteristics ..............................................................................................................................22
3.1. Absolute Maximum Ratings ..................................................................................................................22
3.2. Operating Conditions .............................................................................................................................23
3.3. Pin Out......................................................................................................................................................23
3.3.1. A2541R24x10 (Module with TI BLE Stack).....................................................................................23
3.3.2. A2541R24x20 (Module with Emmoco EM-Ware Firmware)...........................................................25
3.4. Recommended Layout (dimensions in mm) .......................................................................................27
3.5. Power Supply Considerations ...............................................................................................................29
4. Mechanical and Process................................................................................................................................30
4.1. Radio Module Details (dimensions in mm).........................................................................................30
4.1.1. A2541R24A ......................................................................................................................................30
4.1.2. A2541R24C.......................................................................................................................................30
4.2. Packaging Details (dimensions in mm)...............................................................................................31
4.2.1. Matrix Tray Packaging .....................................................................................................................31
4.2.2. Tape-Reel Packaging .........................................................................................................................31
4.3. Soldering...................................................................................................................................................32

4.3.1. Manual Mounting Procedure ...........................................................................................................32
4.3.2. Automated Mounting Procedure ......................................................................................................33

A2541R24x –User’s Manual Page 5 of 36
Release Date 11/22/13
1. Overview
The A2541R24A and A2541R24C are surface mount 2.4GHz RF transceivers incorporating
Bluetooth®SMART technology per the Bluetooth v4.0 core specification. The A2541R24A has
an integral antenna, whereas the A2541R24C utilizes an external antenna through a U.FL
connector (see Table 1). These modules incorporate crystals, a step down converter, the
required RF matching and filtering for regulatory compliance as well as filtering for noise
reduction and sensitivity. They operate in the global unlicensed 2.4GHz ISM/SRD frequency
band. The modules are ideal for achieving low power, long range wireless connectivity without
having to deal with extensive protocol, RF, antenna design and regulatory compliance, and
provide quick time to market. They are 100% tested to provide consistent performance.
The A2541R24A and A2541R24C modules have received regulatory approvals for modular
devices in the United States (FCC), Canada (IC) and Europe (ETSI). The modular approval
allows the end user to place either an A2541R24A or an A2541R24C with an approved antenna
inside a finished product without having to perform costly regulatory testing for an intentional RF
radiator. Section 2.3 has information on the requirements for the end user/integrator to fulfill in
order to use the modules without intentional radiator regulatory testing.
The A2541R24A and A2541R24C are based on the CC2541 SoC transceiver from Texas
Instruments (TI). The CC2541 combines the excellent performance of a leading RF transceiver
with an industry-standard enhanced 8051 microcontroller unit (MCU), 256-KB in-system
programmable flash memory, 8-KB RAM with retention in all power modes, and many other
powerful features. The CC2541 has various operating modes, making it highly suited for
systems where ultralow power consumption is required. Short transition times between
operating modes further ensure low energy consumption. All control lines are provided at
module level for full control of the operation. Please see the user’s guide for CC2541
(www.ti.com) for how to operate, program and control these modules.
The A2541R24A and A2541R24C modules are available loaded with either “BLE Stack”
firmware from Texas Instruments (part number suffix “10”) or “EM-Ware based on BLE Stack”
firmware (part number suffix “20”) from Emmoco, a leader in embedded mobile
connectivity. More information is available for the TI BLE Stack at http://www.ti.com/tool/ble-
stack, and for Emmoco EM-Ware at http://www.emmoco.com.
The A2541R24A and A2541R24C modules measure 11 mm x 19 mm x 2.5 mm. The modules
are footprint compatible with each other.
1.1. A2541R24A
The A2541R24A 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. See Figure 9 - Figure 10 for more information on antenna
location and enclosure considerations.

Page 6 of 36 A2541R24x –User’s Manual
Release Date 11/22/13
1.2. A2541R24C
The A2541R24C 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. Please see Table 1
for a list of approved antennas.
1.3. Features
Features:
2.4 GHz incorporating Bluetooth Smart
technology and Proprietary RF System-
on-Chip
2.0 to 3.6 V operation
High-Performance and low-power 8051
microcontroller core
256 kB Programmable Flash
8 kB RAM with retention in all power
modes
Programmable output power up to +1
dBm
18 General Purpose I/O Pins
Features TI’s TPS62730 step-down
converter
Low current consumption (14mA in RX
and, 13mA @0dBm TX with step down
converter ON)
Excellent receiver sensitivity, -90 dBm
average in BLE HGM with <1% PER.
3 Low power/sleep modes from 0.5µA
to 270µA.
General-Purpose Timers (One 16-Bit,
Two 8-Bit), 32-kHz Sleep Timer with
Capture
RSSI support
Battery Monitor and Temperature
Sensor
12-Bit ADC with eight channels and
configurable resolution
AES Security Coprocessor
2 USARTs with several serial protocol
support
Watchdog Timer
RoHS Compliant
Shielded package
LGA Footprint
Benefits Summary:
Operating temperature-40 oC to +85 oC
100% RF Tested in production for
repeatable performance
No RF engineering experience
necessary
No protocol experience necessary
Only requires a 2 layer Host PCB
implementation
FCC 15.247, IC RSS-210 and IC RSS-
Gen certified.
Compliant with ETSI EN 300 328
No regulatory “Intentional radiator”
testing required for integrating module
into end product. Simple certification
labeling replaces testing.

A2541R24x –User’s Manual Page 7 of 36
Release Date 11/22/13
Very Small package size:
11mm x 19mm x 2.5mm
Approximate weight 0.7 grams
1.4. Theory of Operation
The A2541R24A and A2541R24C modules operate in the global 2.4 GHz ISM/SRD frequency
band. They can be used to implement a variety of networks, including point to point, point to
multi-point, peer to peer and mesh networks.
Figure 1 and Figure 2 show the functionality of A2541R24A and A2541R24C, respectively. Both
modules operate in a similar manner except the antenna part where A2541R24A communicates
through a built-in antenna, and A2541R24C communicates through an external antenna
attached to a U.FL antenna port.
Figure 1 The functionality of the A2541R24A, using an internal antenna

Page 8 of 36 A2541R24x –User’s Manual
Release Date 11/22/13
Figure 2 The functionality of the A2541R24C, using an external antenna
The description of the functional blocks shown in Figure 1 and Figure 2 is given as follows:
Antenna
oThe antenna couples energy between the air and the module. The integral
antenna and the external monopole antenna, both centered at 2441.75 MHz,
provide a near omni-directional antenna pattern with high efficiency such that the
application will work in any direction. Note that the end radiation pattern depends
not only on the antenna, but also the ground plane, enclosure and installation
environment.
Matching & Filtering
oThe 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.
oFiltering removes spurious signals to comply with regulatory intentional radiator
requirements, provides reduced susceptibility to power supply and digital noise,
and filters out RF and high frequency noise from the communication data and
control link.
TX/RX Chain
oTX/RX chain handles transmitting and receiving of the communication data
based on the radio register settings. It involves the coordination of several blocks
including modulator, demodulator, AGC control, frequency synthesizer and frame
control.
Crystal
oCrystal oscillator provides the necessary clock reference for the whole module
operation. The A2541R24A and A2541R24C modules use two crystals: a 32
MHz crystal and a 32.768 kHz crystal.
Power Management

A2541R24x –User’s Manual Page 9 of 36
Release Date 11/22/13
oPower management ensures a stable supply for the internal functions, as well as
providing means for a low power sleep mode.
CPU and Memory
oThe 8051 CPU core used in the CC2541 device is a single-cycle 8051-
compatible core. It has three different memory-access buses (SFR, DAT and
CODE/XDATA) with single-cycle access to SFR, DATA, and the main SRAM. It
also includes a debug interface and an 18-input extended interrupt unit.
oThe memory arbiter connects the CPU and DMA controller with the physical
memories and all peripherals through the SFR bus.
oThe 8-KB SRAM maps to the DATA memory space and to parts of the XDATA
memory spaces. This is an ultralow-power SRAM that retains its contents even
when the digital part is powered off.
o256 KB flash block provides in-circuit programmable non-volatile program
memory for the device, and maps into the CODE and XDATA memory spaces. In
addition to holding the program code, it also allows the application to save data
that must be preserved such that it is available after restarting the device.
I/O Controller
oThe I/O controller is responsible for all general-purpose I/O pins. The CPU can
configure whether peripheral modules control certain pins or they are under
software control, and if so, whether they are configured as input or output.
Step-Down Converter (TPS62730)
oThe step-down converter (TPS62730, DC-DC Converter) provides a fixed 2.1V
input voltage to the transceiver chip internally when it is in DC-DC mode and the
module input voltage is above 2.3V.
oBYPASS mode with a typical 30nA current consumption supports the module’s
sleep and low power modes.
oThe step-down converter can be controlled via firmware or by an external signal
on module pin 16. When controlled by firmware the converter is placed into
Bypass mode whenever the CC2541 is in a low-power state, otherwise the
converter is ON (i.e. switching). This helps reduce overall power consumption for
systems operating above 2.1V since the CC2541 device is powered by the
output of the TPS62730 instead of the radio module’s supply pin. That equates to
about 30% reduction in current draw while the radio is in a higher power active
state when operating at 3.0V and about 40% reduction in current when operating
at 3.6V (current reduction is at module input).
oWhen the converter is in DC-DC mode the radio module’s I/O signals will be at
2.1V logic levels, whereas in Bypass mode the I/O will be at logic levels equal to
the module’s supply voltage. This is an important consideration when deciding
whether to force the DC-DC converter into Bypass mode or allow firmware to
cycle between ON and Bypass. In the latter scenario, all devices that interface to
the A2541 must be compatible with the changing logic levels.
oConnections to the step-down converter pins are identified in Figure 3 below. For
brevity, filtering components are not shown.

Page 10 of 36 A2541R24x –User’s Manual
Release Date 11/22/13
Figure 3 Internal connections for TPS62730 Step-Down Converter
Table 1 Approved Antennas
Item
Part Number
Manufacturer
Type
Gain (dBi)
1
Integral part of A2541R24A
Anaren
Integral Antenna
2
2
66089-2406
Anaren
Monopole whip, 6 mm lead
3
3
66089-2430
Anaren
Monopole whip, 30 mm lead
3
1.5. Applications
Bluetooth SMART Systems
Industrial Control and Monitoring
Home/Building Automation
Lighting Systems
Low-Power Wireless Sensor Networks
Sports monitoring, health & wellness