Freescale Semiconductor KW2xDxxx User manual

Document Number: TWR-KW2xDxxxHWRM
Rev. 0.2
10/2013
Tower KW2xDxxx Hardware
Reference Manual

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Tower MKW2xDxxx Hardware Reference Manual, Rev. 0.2
Freescale Semiconductor iii
Contents
Chapter 1
Safety Information
1.1 FCC Guidelines. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
1.1.1 Labeling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
1.1.2 Operating Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
1.1.3 Exposure Limits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
1.1.4 Antenna Restrictions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
1.2 Regulatory Approval For Canada (IC RSS 210) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
1.2.1 26 PART 5 – Appendix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
1.3 Electrostatic Discharge Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
1.4 Disposal Instructions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
Chapter 2
TWR-KW2xDxxx Development Platform Overview and Description
2.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
2.2 Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
2.3 Software and Driver Considerations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4
Chapter 3
TWR-KW2xDxxx
3.1 TWR-KW2xDxxx Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
3.1.1 PCB Board Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
3.1.2 Form Factor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
3.1.3 Board Level Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3
3.2 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4
3.2.1 RF Performance and Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5
3.2.2 Clocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6
3.2.3 Power Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7
3.2.4 TWR-KW2xDxxx Peripheral Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-9
3.2.4.1 Serial FLASH (SPI Interface). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-9
3.2.4.2 TWRPI Connectors J9 and J10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-10
3.2.4.3 Jumper Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-11
3.2.4.4 MKW24D512 USB Supply (J6) - TWR-MK24D512 Board Only . . . . . . . . . . . . . . . 3-12
3.2.4.5 MKW21D256 (Non-USB) UART2 Support - TWR-MK21D256 Board Only . . . . . . 3-12
3.3 Schematic, Board Layout, and Bill of Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-13
3.3.1 Bill of Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-20
Chapter 4
PCB Manufacturing Specifications
4.1 Single PCB Construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
4.2 Panelization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2
4.3 Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2

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4.4 Solder Mask . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3
4.5 Silk Screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3
4.6 Electrical PCB Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3
4.7 Packaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3
4.8 Hole Specification/Tool Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3
4.9 File Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4

Tower KW2xDxxx Hardware Reference Manual, Rev. 0.2
Freescale Semiconductor v
About This Book
This manual describes Freescale’s TWR-KW2xDxxx development platform hardware. The
TWR-KW2xDxxx is an IEEE® 802.15.4 compliant evaluation environment based on the Freescale
MKW2xDxxx device. The MKW2xDxxx family is Freescale's latest generation ZigBee™ platform,
which incorporates a complete low power 2.4 GHz radio frequency transceiver and a Kinetis family low
power, mixed-signal ARM Cortex™-M4 MCU into a single package. This family of products is targeted
to meet the higher performance requirements of ZigBee Pro and ZigBee IP based applications, especially
SmartEnergyandCommercialBuildingAutomation.Thisproduct is a cost-effectivesolutionthatmatches
or exceeds competitive solutions.
Audience
This manual is intended for system designers.
Organization
This document is organized into the following chapters.
Chapter 1 Safety Information — Highlights some of the FCC requirements.
Chapter 2 TWR-KW2xDxxx Development Platform Overview and Description — Provides
an overview of the boards that comprise the TWR-KW2xDxxx development
platform.
Chapter 3 TWR-KW2xDxxx — This chapter details the TWR-KW21D256 and
TWR-KW24D512 evaluation boards.
Chapter 4 PCB Manufacturing Specifications — This chapter provides the specifications
used to manufacture the various TWR-KW2xDxxx printed circuit boards (PCBs).
Revision History
The following table summarizes revisions to this document since the previous release (Rev. 0.0).
Revision History
Location Revision
Entire document First public release

Tower KW2xDxxx Hardware Reference Manual, Rev. 0.2
vi Freescale Semiconductor
Definitions, Acronyms, and Abbreviations
The following list defines the acronyms and abbreviations used in this document.
ADC Analog to Digital Converter
AES Advanced Encryption Standard
CTS Clear to Send
DAC Digital to Analog Converter
I2C Inter-Integrated Circuit is a multi-master serial computer bus
ISM Industrial Scientific Medical 2.4 GHz radio frequency band
JTAG Joint Test Action Group
LGA Land Grid Array
MAC Media Access Controller
MCU Microcontroller Unit
PCB Printed circuit board
PiP Platform in Package
PWM Pulse-width modulation
RCM Remote Control Module
REM Remote Extender Board
RTS Request to Send
SMA Connector SubMiniature version “A” connector
SoC System on Chip
SPI Serial Peripheral Interface
SSI Synchronous Serial Interface
TACT Switch A switch that provides a slight “snap” or “click” to the user to indicate function.
TELCO Telephone Company
TWR Tower System
USB Universal Serial Bus
VCP Virtual Com Port

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Freescale Semiconductor 1-1
Chapter 1
Safety Information
1.1 FCC Guidelines
This equipment is for use by developers for evaluation purposes only and must not be incorporated into
any other device or system. This device may not be sold to the general public. Integrators will be
responsible for reevaluating the end product (including the transmitter) and obtaining a separate FCC
authorization.
FCC approval of this device only covers the original configuration of this device as supplied. Any
modifications to this product, including changes shown in this manual, may violate the rules of the Federal
Communications Commission and Industry Canada and make operation of the product unlawful.
1.1.1 Labeling
FCC labels are physically located on the back of the board.
1.1.2 Operating Conditions
This device complies with part 15 of the FCC Rules. Operation is subject to the following two conditions:
• This device may not cause harmful interference.
• This device must accept any interference received, including interference that may cause undesired
operation.
1.1.3 Exposure Limits
This equipment complies with FCC radiation exposure limits set forth for an uncontrolled environment.
The antenna(s) used for this equipment must be installed to provide a separation distance of at least 8
inches (20cm) from all persons.
1.1.4 Antenna Restrictions
An intentional radiator shall be designed to ensure that no antenna other than that furnished by the
responsible party shall be used with the device. The use of a permanently attached antenna or of an
antenna that uses a unique coupling to the intentional radiator shall be considered sufficient to comply with
the provisions of this Section. The manufacturer may design the unit so that a broken antenna can be
replaced by the user, but the use of a standard antenna jack or electrical connector is prohibited. This
requirement does not apply to carrier current devices or to devices operated under the provisions of
Sections 15.211, 15.213, 15.217, 15.219, or 15.221. Further, this requirement does not apply to intentional

Safety Information
Tower KW2xDxxx Hardware Reference Manual, Rev. 0.2
1-2 Freescale Semiconductor
radiators that must be professionally installed, such as perimeter protection systems and some field
disturbance sensors, or to other intentional radiators which, in accordance with Section 15.31(d), must be
measured at the installation site. However, the installer shall be responsible for ensuring that the proper
antenna is employed so that the limits in this Part are not exceeded.
1.2 Regulatory Approval For Canada (IC RSS 210)
This device complies with Industry Canada licence-exempt RSS standard(s). Operation is subject to the
following two conditions:
1. This device may not cause interference, and
2. This device must accept any interference, including interference that may cause undesired
operation of the device.
1.2.1 26 PART 5 – Appendix
Le présent appareil est conforme aux CNR d'Industrie Canada applicables aux appareils radio exempts de
licence. L'exploitation est autorisée aux deux conditions suivantes:
1. l'appareil ne doit pas produire de brouillage, et
2. l'utilisateur de l'appareil doit accepter tout brouillage radioélectrique subi, même si le brouillage
est susceptible d'en compromettre le fonctionnement.
1.3 Electrostatic Discharge Considerations
Although damage from electrostatic discharge (ESD) is much less common on these devices than on early
CMOS circuits, normal handling precautions should be used to avoid exposure to static discharge.
Qualification tests are performed to ensure that these devices can withstand exposure to reasonable levels
of static without suffering any permanent damage.
All ESD testing is in conformity with the JESD22 Stress Test Qualification for Commercial Grade
Integrated Circuits. During the device qualification ESD stresses were performed for the human body
model (HBM), the machine model (MM) and the charge device model (CDM).
All latch-up test testing is in conformity with the JESD78 IC Latch-Up Test.
When operating or handling the development boards or components, Freescale strongly recommends
using at least the grounding wrist straps plus any or all of the following ESD dissipation methods:
• Flexible fabric, solid fixed size, or disposable ESD wrist straps
• Static control workstations, static control monitors and table or floor static control systems
• Static control packaging and transportation materials and environmental systems
1.4 Disposal Instructions
This product may be subject to special disposal requirements. For product disposal instructions, refer to
www.freescale.com/productdisposal.

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Chapter 2
TWR-KW2xDxxx Development Platform Overview and
Description
2.1 Introduction
The TWR-KW2xDxxx development platform is an evaluation environment based on the Freescale
MKW21D256 or MKW24D512 SIP devices (MKW2xDxxx).
The MKW2xDxxx device family is Freescale's latest generation ZigBee™ platform which incorporates a
complete low power 2.4 GHz radio frequency transceiver and a Kinetis family low power, mixed-signal
ARM Cortex™-M4 MCU into a single package. Additionally, the MKW2xDxxx comprising of a a 2.4
GHz Industrial, Scientific, and Medical (ISM) and Medical Body Area Network (MBAN) transceiver are
intended for the IEEE® 802.15.4 Standard.
Freescale supplements the MKW2xDxxx with tools and software that include hardware evaluation and
development boards, software development IDE and applications, drivers, custom PHY usable with
Freescale’s IEEE 802.15.4 compatible MAC.
The TWR-KW2xDxxx development platform comprises two boards:
• Tower — TWR-KW21D256 — this board contains the MKW21D256 device with 32 MHz
reference oscillator crystal, RF circuitry including antenna, and supporting circuitry. The board is
astandalone, with a softwarestackto implement an IEEE 802.15.4 Standardplatformsolution. The
following list summarizes the features of the TWR-KW21D256 board.
— Provides compact reference design for device footprint and RF layout.
— Provides pre-designed MKW21D256 hardware (device and function).
— Provides access to the MKW21D256 set of GPIO/Alternate port functions.
— Provides target MCU Cortex 20-pin (0.05”) JTAG debug port.
— Provides a Mini USB Type B coupled with OpenSDA use as debug interface, serial
communication and power supply (J13, Cortex 10-pin (0.05”) JTAG port for OpenSDA
updates).
• Tower — TWR-KW24D512 — this board contains the MKW24D512 device with 32 MHz
reference oscillator crystal, RF circuitry including antenna, and supporting circuitry. The board is
astandalone, with a softwarestackto implement an IEEE 802.15.4 Standardplatformsolution. The
following list summarizes the features of the TWR-KW24D512 board.
— Provides compact reference design for device footprint and RF layout.
— Provides pre-designed MKW24D512 hardware (device and function).
— Provides access to the MKW24D512 set of GPIO/Alternate port functions.
— Provides MCU JTAG Cortex 20-pin (0.05”) JTAG debug port.

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2-2 Freescale Semiconductor
— Provides a Mini USB Type B coupled with OpenSDA used as debug interface, serial
communication and power supply (J13, Cortex 10-pin (0.05”) JTAG port for OpenSDA
updates)
— The TWR-KW24D512 also provides a Micro USB Type AB used as serial communication and
power supply.
Whether the TWR-KW2xDxxx is used in a simple standalone application or in combination with another
reference platform, Freescale provides a complete software development environment called the Freescale
BeeKit Wireless Connectivity Toolkit (BeeKit). BeeKit is a comprehensive codebase of wireless
networking libraries, application templates, and sample applications. A wide range of software
functionality are available to complement the TWR-KW2xDxxx platform and these are provided as
codebases within BeeKit.
2.2 Features
The TWR-KW2xDxxx development platform is built around Freescale’s concept of a standalone Tower
System Modular Development Platform that contains either the MKW21D256 device or the
MKW24D512 device and all necessary I/O connections for use as a self-contained board or for connection
to an application, but also has the capability to connect with the Tower System.
Figure 2-1 shows the TWR-KW2xDxxx development platform:
Figure 2-1. TWR-KW2XDXXX Development Platform
The TWR-KW2xDxxx development platform includes the following Features:
• Freescale’s low-power MKW21D256 or MKW24D512 SIP ZigBee™ platform device
• Fully compliant IEEE 802.15.4 Standard 2006 transceiver supports 250 kbps O-QPSK data in 5.0
MHz channels and full spread-spectrum encode and decode.
• Full IEEE 802.15.4 compliant wireless node; ZigBee capable with Freescale’s BeeStack software
stack.

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Tower KW2xDxxx Hardware Reference Manual, Rev. 0.2
Freescale Semiconductor 2-3
• Reference design area with small footprint, low cost RF node
— Differential input/output port used with external balun for single port operation
— Low external component count
— Programmable output power from –30 dBm to +8 dBm at the SMA connector.
— Receiver sensitivity: –100 dBm, typical (@1% PER for 20 byte payload packet) at the SMA
connector
• Integrated PCB inverted F-type antenna and SMA RF port
• Selectable power sources
• 32 MHz reference oscillator
• 32 kHz reference oscillator
• Pre-certified 2.4 GHz frequency band of operation (ISM)
• Programmable frequency clock output (CLK_OUT)
• External Serial flash for Over-the-air Programming (OTP) support
• General purpose TWRPI connector
•Interfaces:
— SPI, UART, and I2C interface configurations
— ADC and GPIO configurations
• Integrated open-standard serial and debug interface (OpenSDA)
• Supports full speed USB 2.0 (TWR-KW24D512 only)
• Cortex 20-pin (0.05”) JTAG debug port for target MCU
• Cortex 10-pin (0.05”) JTAG port for OpenSDA updates
• 4 blue LED indicators
• 4 push button switches
Figure 2-2 shows a simplified block diagram of the Freescale TWR-KW2XDXXX system.

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Tower KW2xDxxx Hardware Reference Manual, Rev. 0.2
2-4 Freescale Semiconductor
Figure 2-2. Simplified TWR-KW2xDxxx Block Diagram
2.3 Software and Driver Considerations
It is a good idea to install the BeeKit Wireless Connectivity Toolkit package found under Software and
Tools at the following URL before proceeding to use the TWR boards:
• www.freescale.com\zigbee
When users first connect a TWR-KW2xDxxx based platform to a PC, they may be prompted to install
drivers. If BeeKit is installed and this occurs, do not allow Windows to automatically search for and install
the drivers. Instead, select manual installation and steer Windows to the following directory:
C:\Program Files\Freescale\Drivers
Follow the instructions as they appear on the screen to complete driver installation.
NOTE
If installing the BeeKit software package to another drive or directory,
indicate the Drivers directory created by the installer in the custom location
where BeeKit was installed.
If BeeKit is not installed, note the following:
• The boards use the OpenSDA to USB converter, Virtual COM Port (VCP) driver for Windows.
• Download the appropriate driver and follow the instructions to complete driver installation.
— www.pemicro.com/opensda and download the Windows USB Drivers

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Freescale Semiconductor 3-1
Chapter 3
TWR-KW2xDxxx
3.1 TWR-KW2xDxxx Overview
The TWR-KW2xDxxx is an evaluation board based on the Freescale MKW2xDxxx device. The
TWR-KW2xDxxx provides a platform to evaluate the TWR-KW2xDxxx SIP IC, develop software and
applications. The core device is accompanied by the 32 MHz reference oscillator crystal, RF circuitry
including PCB F-type antenna (or SMA), and supporting circuitry.
This basic board is intended as the core PCB for TWR-KW2xDxxx evaluation and application
development and can be used in the following modes:
• Simple standalone evaluation platform
• Daughtercard to other Development Platform boards (Tower System)
• Mothercard to an application specific dauhtercard, could be a TWRPI card.
3.1.1 PCB Board Features
The TWR-KW2xDxxx provides the following features:
• Freescale’s Tower System form factor
• 4-Layer metal, 0.062 inch thick FR4 board
• LGA footprint and power supply bypass
• Printed metal F-Antenna (and SMA)
• 32 MHz reference oscillator crystal
• 32.768 kHz crystal provided for optional timing oscillator.
• Standard Tower TWRPI daughter card mounting interface
— 20-Pin primary connector
— 20-Pin secondary connector
— Can provide main supply voltage to board
3.1.2 Form Factor
Figure 3-1 shows the TWR-KW2xDxxx connector and header locations.

TWR-KW2xDxxx
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3-2 Freescale Semiconductor
Figure 3-1. TWR-KW2xDxxx Connector and Header Details
The TWR-KW2xDxxx incorporates the following general headers.
Headers J9 and J10:
• Both headers have standard 0.05in / 1.27 mm pin spacing
• J9 and J10 are 20-pin
• Both are pin headers mounted on the Top side of the board and are intended to plug into matching
receptacles on the TWRPI standard.
Headers J17 and J18:
• Both headers have standard 0.10in / 2.54 mm pin spacing
• J17 and J18 are 3x4-pin
• Both are pin headers mounted on the Top side of the board and are intended to have the capability
for SPI/TWR_Elevator Selector (J17) and UART1/TWR_Elevator Selector (J18).
Headers J19, J20, J21, and J24:
• Headers have standard 0.10in / 2.54 mm pin spacing
• J19, J20, J21, and J24 are 3-pin
• 19, J20, J21, and J24 are pin headers mounted on the Top side of the board and are intended to
select between UART0/LED.

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Freescale Semiconductor 3-3
Figure 3-2 shows a footprint of the TWR-KW2xDxxx with the location of the IO Headers.
Figure 3-2. TWR-KW2xDxxx Top Side (Component Side) Footprint
3.1.3 Board Level Specifications
Table 3-1. TWR-KW2xDxxx Specifications
Parameter Units Notes/Conditions
MIN TYP MAX
General
Size (PCB: X, Y) 90 x 80.6
3.54 x 3.175 mm inches
Layer build (PCB) 1.57
0.062 mm inches 4-Layer
Dielectric material (PCB) FR4
Power
Current consumption
Transmit
Receive
18
20
18
20
mA *Board level measured at J2. Radio TX (Nominal power)
MCU
Radio RX mode
MCU

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3-4 Freescale Semiconductor
Temperature
Operating temperature (see note) -40 +25 +70 °C • Operating temperature is limited to +70
°C due to switches. Basic circuit is good
for a maximum temperature of +85 °C.
Storage temperature -30 +25 +70 °C
RF
802.15.4 Frequency range 2405 2480 MHz All 16 channels in the2450 MHz band
RF Receiver
Saturation (maximum input level) +10 dBm
Sensitivity for 1% packet error rate (PER)
(+25 °C) -100 dBm
RF Transmitter
RF Power Output -32 +10 dBm Programmable in 2dB steps
2nd harmonic <-50 <-40 dBm Measured with output power set to nominal
(0dBm) andtemperature@25°C. Trap filter
is needed.
3rd harmonic <-50 <-40 dBm Measured with output power set to nominal
(0dBm) andtemperature@25°C. Trap filter
is needed.
Regulatory Approval
FCC Product is approved accordingly to the FCC
part 15 standard
CE (ETSI) Product is approved accordingly to the EN
300 328 V1.7.1 (2006-10) standard
CE (EMC) Product is approved accordingly to the EN
301 489-1 V1.6.1 (2005-09) and EN 301
489-17 V1.2.1 (2002-08) standards
Safety
UL Product is approved accordingly to the IEC
60950-1 and EN 60950-1, First Edition
standards
Environment
RoHS Product complies with the EU Directive
2002/95/EC of 27 January 2003
WEEE Product complies with the EU Directive
2002/95/EC of 27 January 2003
Table 3-1. TWR-KW2xDxxx Specifications (continued)
Parameter Units Notes/Conditions

TWR-KW2xDxxx
Tower KW2xDxxx Hardware Reference Manual, Rev. 0.2
Freescale Semiconductor 3-5
3.2 Functional Description
The TWR-KW2xDxxx is built around Freescale’s MKW2XDXXX 56-pin LGA platform and is intended
as a simple evaluation platform and as a building block for application development. The 4-layer board
providestheMKW2XDXXX with its required RF circuitry, 32 MHz reference oscillator crystal and power
supply bypassing. The layout for this base level functionality can be used as a reference layout by the user
target board.
3.2.1 RF Performance and Considerations
TWR-KW2xDxxx transceiver includes a 1mW nominal output power, PA with internal voltage controlled
oscillator (VCO), integrated transmit/receive switch, on-board power supply regulation, and full
spread-spectrum encoding and decoding. Key specifications for MKW2XDXXX are:
• Nominal output power is 0 dBm, with +10 dBm max
• Programmable output power from –30 dBm to +10 dBm (measured at the package pin)
• Frequency range is 2360 to 2480 MHz (Includes both ISM and MBAN bands)
• Receiver sensitivity: –102 dBm, typical (@1% PER for 20 byte payload packet, measured at the
package pin)
• Differential bidirectional RF input/output port with integrated transmit/receive switch
The TWR-KW2xDxxx utilizes a minimum number of components while providing good RF performance:
• Uses a minimum number of RF marching components and external 50:50 balun.
• “F” printed metal antenna for a small footprint, low cost design.
An external 50 (unbal): 50(bal) balun connects a single-ended 50-ohm port to the differential RF port of
the MKW2XDXXX radio. The layout has provision for out-of-band signal suppression (components L5
and C19) if required.
Figure 3-3. TWR-KW2xDxxx RF Circuitry

TWR-KW2xDxxx
Tower KW2xDxxx Hardware Reference Manual, Rev. 0.2
3-6 Freescale Semiconductor
3.2.2 Clocks
The TWR-KW2xDxxx provides two clocks:
• 32 MHz Reference Oscillator - Figure 3-4 shows the external 32 MHz external crystal Y1. This
mounted crystal must meet the MKW2XDXXX specifications. The IEEE 802.15.4 Standard
requires that the frequency be accurate to less that +/-40 ppm.
— Capacitors C21 and C22 provide the bulk of the crystal load capacitance. Onboard trim
capacitors can be programmed to center the frequency. At 25°C, it is desired to have the
frequency accurate to +/-10 ppm or less to allow for temperature variation.
— To measure the 32 MHz oscillator frequency, signal CLK_OUT (PTA18) can optionally be
programmed to provide a buffered output clock signal
— The TWR-KW2xDxxx has provision for injecting an external 32 MHz clock source as an
alternative to use of the onboard crystal:
– The crystal Y1 should be removed
– C20 must be mounted
– The external 32 MHz source is connected to 2-pin header J5; the frequency accuracy of the
external source must meet the +/-40 ppm of the IEEE 802.15.4
Figure 3-4. 32 MHz Reference Oscillator Circuit
• Optional32.768kHz CrystalOscillator-Provisionisalso made for asecondary 32.768 kHz crystal
Y2 as shown in Figure 3-5. This oscillator can be used for a low power accurate time base.
— The module comes provided with the 32.768 kHz crystal.
— Load capacitors C23 and C24 provide the entire crystal load capacitance; there is no onboard
trim capacitance.

TWR-KW2xDxxx
Tower KW2xDxxx Hardware Reference Manual, Rev. 0.2
Freescale Semiconductor 3-7
Figure 3-5. 32.768 kHz Optional Oscillator Circuit
3.2.3 Power Management
The TWR-KW2xDxxx power management circuit is shown in Figure 3-6.
Figure 3-6. TWR-KW2xDxxx Power Management Circuit
The TWR-KW2xDxxx has the flexibility to be powered in several configurations:
• Board can be supplied through the mini USB type B connector (J15) which provides P5V_USB to
J1 1-2.
• Board can be supplied through the micro USB AB (J6) (TWR-KW24D512 only) providing
P5V_KW24_USB to J27 1-2 and VOUT33 to J3 2-3.
• Board can be supplied through the TWR System Elevator headers which provides either
3.3V_ELEV or 5V_ELEV to header J1 3-4 or J1 5-6 respectively.
• Board can be supplied from an external DC supply in the following ways:
— Connect an USB battery adaptor capable of suppling 1.8 to 5.5 VDC to the micro USB AB (J6)
(TWR-KW24D512 only)

TWR-KW2xDxxx
Tower KW2xDxxx Hardware Reference Manual, Rev. 0.2
3-8 Freescale Semiconductor
— An external unregulated supply up to 5.5VDC can be supplied to V_EXT header J28 making
use of the onboard 3.3 V LDO regulator
Header J2 provides the means to supply either the MCU, the radio and LED circuits. Current
measurements can be made by inserting a current meter in place of a designated jumper. Connections
configurations are described in Table 3-2.
3.2.4 TWR-KW2xDxxx Peripheral Functions
The TWR-KW2xDxxx includes the TWRPI general purpose peripheral function to assist in implementing
targeted applications. The TWR-KW2xDxxx board also has alternate port functions routed to the elevator
interface where off board tower system peripherals can be used if desired.
3.2.4.1 Serial FLASH (SPI Interface)
Component U13 is an AT45DB161E-SSHD 16 Mbit (2 Mbyte) serial Flash memory with SPI interface.
The memory is useful for over-the-air programming (OTAP) and for storage of non-volatile system data
or parameters. Figure 3-7 shows the memory circuit.
• Memory power supply is V_MCU
• Discrete pullup resistors for the SPI port are provided
• The SPI can be shared with another peripheral with the TWRPI J10 connector — an additional IO
signal would be required as a chip enable (CS or SS) for the peripheral. The normal SPI_SS and
the second chip select should NOT be active at the same time.
• The SPI Write Protect and Reset signals have discrete pullup resistors for control if required. The
resistors are DNP.
Table 3-2. Power Distribution Header J2
Supply
Designation Header Pins Description
V_LED 1 - 2 Supply voltage to power indicator LED
• Normally jumpered
• Jumper used to enable LEDs on board
• Leave open for lowest power
• Usage: Measure LED current
V_MCU 3 - 4 Supply voltage to MKW2xDxxx
• Normally jumpered
• Supplies only the MKW2xDxxx MCU
• Usage: Measure or supply MCU current
V_RF 5 - 6 Supply voltage to MKW2xDxxx
• Normally jumpered
• Supplies only the MKW2xDxxx transceiver
• Usage: Measure or supply radio current