NXP Semiconductors AN11524 Installation and operating instructions

AN11524
NXQ1TXA6 Evaluation Board
Rev. 1 — 17 February 2015 Application note
Document information
Info Content
Keywords NXQ1TXA6, NWP2081, Wireless Charging, Qi, mobile devices, base
station, magnetic coupled power transfer
Abstract This document illustrates how to create a Qi A6 wireless power base
station. It uses the NXQ1TXA6 charging controller and its evaluation board
that can deliver up to 5 W effective output at the wireless mobile device
side

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Application note Rev. 1 — 17 February 2015 2 of 54
Contact information
For more information, please visit: http://www.nxp.com
For sales office addresses, please send an email to: [email protected]
NXP Semiconductors AN11524
NXQ1TXA6 Evaluation Board
Revision history
Rev Date Description
v. 1.0 20150217 Initial version

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NXP Semiconductors AN11524
NXQ1TXA6 Evaluation Board
1. Introduction
The ubiquity of mobile phones, increases the requirement of a convenient way to charge
these devices while on the move. Especially the fast risingnumber of smart phones widely
used and relied upon in daily life. Wireless charging is introduced into smart phones and
tablets.
Wireless charging represents the future of public and private charging.
Qi (pronounced as "Chee") is a wireless charging standard developed by Wireless Power
Consortium (www.wirelesspowerconsortium.com) for inductive power.
The Qi system (see Figure 1) comprises a base station or a transmitter (TX) pad and a
mobile device or a compatible receiver (RX), such as a mobile phone. To use the system,
the mobile device is placed on top of the base station pad which charges the device via
electromagnetic induction.
The market demand for the convenience and safety of standard-compliant wireless power
systems continues to grow rapidly.
NXP offers Qi-compliant base station reference designs to set you immediately on your
way to a successful project. NXP supports several types of Qi base stations. This
document describes the application of an A6 type base station using NXQ1TXA6 charging
controller.
Fig 1. Wireless charging system as defined by Wireless Power Consortium
aaa-014485
BASE STATION
TRANSMITTER
COMM
messages
reflected load
power
CONTROL
SYSTEM
POWER CONVERSION
demod
MOBILE DEVICE
RECEIVER
CONTROLCOMM
LOAD
POWER PICK-UP
mod

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NXP Semiconductors AN11524
NXQ1TXA6 Evaluation Board
2. Scope
This document discusses the design of a WPC Qi A6 type base station based on the NXP
NXQ1TXA6 Evaluation Board. The NXQ1TXA6 Evaluation Board is Qi certified and it
complies with EMI regulation - EN55022 and FCC part 18.
The document is intended to provide engineers with real life practical design applications
and get them started on the right note immediately.
For all topics covered, hints are provided to ensure system-level best performance,
excellent EMC and lowest application cost.
Near Field Communication (NFC) option for tap to power on to enable zero power standby
and Bluetooth pairing is included. There are many other use cases and possibilities with
NFC technology but they are not within the scope of this application note.

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NXP Semiconductors AN11524
NXQ1TXA6 Evaluation Board
3. Getting started
3.1 Package contents
The evaluation kit contains the following items:
•NXP NXQ1TXA6 wireless charger evaluation board containing, see Figure 2:
–NXQ1TXA6 charger controller IC
–NWP2081 half-bridge level shift controller IC
–NX2020 MOSFETs
–NT3H1201 NTAG-I2C NFC forum tag
•AC 110 V/220 V – DC 12 V power supply containing:
–TEA1720B3T HV start-up fly-back controller for ultra-low no-load charger
applications up to 12 W
A mobile device to receive the power is not included in the evaluation package. Refer to
the WPC website for a list of certified Qi receivers to be used with the evaluation board. To
demonstrate NFC tap to power on, ensure that the receivers support both Qi wireless
charging and NFC technology.
Fig 2. Overview of the charging pad
aaa-015876

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NXP Semiconductors AN11524
NXQ1TXA6 Evaluation Board
3.2 Main features
The NXQ1TXA6 Evaluation Board demonstrates:
•A reference design with key components from NXP for wireless charging applications
based on inductive power transfer standard Qi.
•Shows additional benefits resulting from integration of NFC with wireless charging.
Enabling for example zero power standby with the “tap to power on” feature.
3.3 System efficiency
In Figure 3, the system efficiency of the evaluation board is shown using a standard off the
shelf receiver.
System efficiency is measured as the ratio of output power of the receiver to the input
power of the transmitter. Input power is averaged to take into account variation due to
communication between receiver and transmitter.
The quality of the components used in both the transmitter and the receiver, determine the
efficiency of the system.
3.4 Board overview
The evaluation board is shown in Figure 4. The left-hand side contains the charging area
where the mobile device should be placed. The top right side has the electronics to drive
the charging coil and communicate with the mobile device.
(1) outer coil 1
(2) center coil
(3) outer coil 2
Fig 3. System efficiency
output power (mW)
0 5,0004,0002,000 3,0001,000
aaa-015880
40
20
60
80
η
(%)
0
(1)
(2)
(3)

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NXP Semiconductors AN11524
NXQ1TXA6 Evaluation Board
The function of the switch and push buttons as well as the meaning of the status LED is
explained in the next subsections.
Fig 4. Switch, buttons and status LED location overview
aaa-015882
LED
stand-by power
mode switch
12 V DC
input
FOD
button
reset
button
charging area

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NXP Semiconductors AN11524
NXQ1TXA6 Evaluation Board
3.5 Stand-by power mode switch
The switch on the top of the board is not a power on/off switch. The switch is for
alternating between the “Normal” and the NFC “tap to power on” position as illustrated in
Figure 5.
In the Normal mode, the charging pad periodically monitors the coil for the presence of a
Qi receiver. It starts power transfer, once a Qi power receiver is detected.
In the NFC tap to power on mode, the charging pad electronics are disconnected from the
12 V supply. The presence of an NFC enabled phone, switches on the 12 V system
supply, enabling zero power in standby mode.
Important:
The present generation of NFC phones only performs periodic NFC operations when the
display of the phone is on and unlocked. It is only under this condition that the charging
pad is woken-up to start power transfer.
3.6 Reset button
Pressing the reset button marked SW101 on the board performs a reset of the charging
pad.
3.7 Foreign object detection button
By pressing the left-most button marked SW102 on the board, the charging pad enables
or disables Foreign Object Detection (FOD). This feature should be removed for final
products.
While charging, the green status LED indicates whether FOD is activated. When FOD is
active, the green LED blinks with a rate of 1 Hz. When FOD is disabled, the green LED
blinks with a rate of 3 Hz.
Fig 5. Standby-by power mode switch
aaa-015883
normal mode
position
NFC tap to
power on position

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NXQ1TXA6 Evaluation Board
3.8 Status LED
An overview of the status signaled by the LEDs is given in the following table:
3.9 NFC functionality
The evaluation board provides a passive tag functionality with NT3H1201 NTAG-I2C. The
NTAG-I2C is preprogrammed with a URL link to the NXP website. When most NFC
phones are put on the charger pad while the screen is active, an automatic link to the NXP
website is made.
Other content can be programmed into NTAG IC by using, for example, NXPs TagWriter.
Table 1. LED status indicator
LED status Description
Off If a 12 V DC supply is present, the pad is in the
operation mode as defined by the mode switch
Green blinking 1 Hz Ongoing power transfer - charging mobile
device, FOD enabled
Green blinking 3 Hz Ongoing power transfer - charging mobile
device, FOD disabled
Green permanently On Mobile device charged
Red blinking No power transfer
Error detected: Foreign object, temperature or
Receiver indicated error

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Application note Rev. 1 — 17 February 2015 10 of 54
NXP Semiconductors AN11524
NXQ1TXA6 Evaluation Board
4. NXP product offering
The NXQ1TXA6 evaluation board was designed based on the NXP products listed in
Table 2. The part numbers are hyperlinked to the NXP website to provide quick access to
product information and data sheets.
Table 2. NXP components for wireless charger application
Type number Function Package Ordering
information
Version Description 12NC
NXQ1TXA6/001 Wireless charger
controller SOT865 HVQFN: plastic thermal enhanced very thin quad flat package; no leads; 33 terminals;
body 7 7 0.85 mm
9353 039 36551
NWP2081T Half-bridge level-shift
controller IC SOT96 plastic small outline package; 8 leads; body width 3.9 mm 9353 021 87518
NX3008NBKW 30 V, single N-channel
Trench MOSFET SOT323 plastic surface-mounted package; 3 leads 9340 656 35115
NX2020N2 30 V, single N-channel
Trench MOSFET SOT1220 plastic thermal enhanced ultra thin small outline package; no leads; 6 terminals 9340 682 45115
BAS21 High-voltage switching
diodes SOT23 plastic surface-mounted package; 3 leads 9335 020 40215
BAT54S Schottky barrier diodes SOT23 plastic surface-mounted package; 3 leads 9339 763 80215
TL431 Adjustable precision
shunt regulator SOT23 plastic surface-mounted package; 3 leads 9352 932 76215
Optional
NT3H1201 NTAG-I2C NFC forum
type 2 Tag compliant IC
with I2C interface
SOT902 plastic extremely thin quad flat package; no
leads; 8 terminals 9353 028 43125
NX3008CBKS 30 V complementary N/P
channel Trench
MOSFET
SOT363 plastic surface-mounted package with
increased, 6 leads 9340 682 44115
NX2020P1 30 V, single P-channel
Trench MOSFET SOT1220 plastic thermal enhanced ultra thin small outline package; no leads; 6 terminals 9340 656 39115
BAT54C Schottky barrier (double)
diodes SOT23 plastic surface-mounted package; 3 leads 9339 763 70215
TDA3663 LDO (or use DC-to-DC
RT8295A) SOT223 plastic surface-mounted package with increased heatsink; 4 leads 9352 629 68135
TEA1720B3T 12 W HV start-up fly
back controller (SMPS) SOT96 plastic surface-mounted package; 8 leads 9353 026 97118