IEC 63563-4:2025

IEC 63563-4 ®
Edition 1.0 2025-02
INTERNATIONAL
STANDARD
Qi Specification version 2.0 –
Part 4: Power Delivery
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IEC 63563-4 ®
Edition 1.0 2025-02
INTERNATIONAL
STANDARD
Qi Specification version 2.0 –

Part 4: Power Delivery
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.240.99; 35.240.99 ISBN 978-2-8327-0187-4

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INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
QI SPECIFICATION VERSION 2.0 –
Part 4: Power Delivery
FOREWORD
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IEC 635-4 has been prepared by technical area 15: Wireless Power Transfer, of IEC
technical committee 100: Audio, video and multimedia systems and equipment. It is an
International Standard.
It is based on Qi Specification version 2.0, Power Delivery and was submitted as a Fast-Track
document.
The text of this International Standard is based on the following documents:
Draft Report on voting
//FDIS //RVD
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Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
The structure and editorial rules used in this publication reflect the practice of the organization
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specific document. At this date, the document will be
x reconfirmed,
x withdrawn, or
x revised.
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WIRELESS POWER
CONSORTIUM
Qi Specification
Power Delivery
Version 2.0
April 2023
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DISCLAIMER
Theinformationcontainedhereinisbelievedtobeaccurateasofthedateofpublication,
butisprovided“asis”andmaycontainerrors.TheWirelessPowerConsortiummakesno
warranty,expressorimplied,withrespecttothisdocumentanditscontents,includingany
warrantyoftitle,ownership,merchantability,orfitnessforaparticularuseorpurpose.
NeithertheWirelessPowerConsortium,noranymemberoftheWirelessPower
Consortiumwillbeliableforerrorsinthisdocumentorforanydamages,includingindirect
orconsequential,fromuseoforrelianceontheaccuracyofthisdocument.For any further
explanation of the contents of this document, or in case of any perceived inconsistency or ambiguity
of interpretation, contact: info@wirelesspowerconsortium.com.
RELEASE HISTORY
Specification Version Release Date Description
2.0 April 2023 Initial release of the v2.0 Qi Specification.

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Table of Contents
1  General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1 Structure of the Qi Specification. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.3 Compliance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.4 References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.5 Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.6 Power Profiles. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2  Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3  Power Receiver construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.1 Dual resonant circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.2 Rectification circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.3 Sensing circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.4 Communications modulator. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.5 Communications demodulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.6 Output disconnect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.7 Shielding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
4  Power Receiver design guidelines (informative) . . . . . . . . . . . . . . . . . . . . . . . . . 17
4.1 Large-signal resonance check. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
4.2 Power Receiver coil design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
5  Power Transmitter construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
5.1 Power Transmitter reference designs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
5.2 Power transfer control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
6  Power consumption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
7  Meaningful functionality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
8  Unintentional Magnetic Field Susceptibility (Informative) . . . . . . . . . . . . . . . . . 24
8.1 Limits. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
8.2 Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
8.3 Power Transmitter detection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
9  Load Steps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
9.1 Load step test procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
9.2 Load dump test procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

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10  Over-voltage protection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
11  External Power Input (Informative) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
11.1 Available power—Extended Power Profile only. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
12  Power Levels (Extended Power Profile only) . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
12.1 Potential Load Power. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
12.2 Light load. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
13  System Efficiency (Informative). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
13.1 Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
13.2 Power Transmitter efficiency. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
13.3 Power Receiver efficiency. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
14  Stand-by Power (Informative) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
14.1 Transmitter Measurement Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
15  Object Detection (Informative) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
15.1 Resonance shift . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
15.2 Capacitance change. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
16  Power Receiver Localization (Informative). . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
16.1 Primary Coil array based Free Positioning. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
16.2 Moving Primary Coil based Free Positioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
16.3 User-assisted positioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

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1 General
The Wireless Power Consortium (WPC) is a worldwide organization that aims to develop and
promote global standards for wireless power transfer in various application areas. A first
application area comprises flat-surface devices such as mobile phones and chargers in the
Baseline Power Profile (up to 5 W) and Extended Power Profile (above 5 W).
1.1 Structure of the Qi Specification
General documents
ƒ Introduction
ƒ Glossary, Acronyms, and Symbols
System description documents
ƒ Mechanical, Thermal, and User Interface
ƒ Power Delivery
ƒ Communications Physical Layer
ƒ Communications Protocol
ƒ Foreign Object Detection
ƒ NFC Tag Protection
ƒ Authentication Protocol
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1.2 Scope
The QiSpecification,PowerDelivery (this document) comprises guidelines and requirements for
Power Receiver design, including circuitry, power consumption, operating power levels, power
transfer efficiency, and standby power.
1.3 Compliance
All provisions in the QiSpecification are mandatory, unless specifically indicated as recommended,
optional, note, example, or informative. Verbal expression of provisions in this Specification follow
the rules provided in ISO/IEC Directives, Part 2.
Table 1: Verbal forms for expressions of provisions
Provision Verbal form
requirement “shall” or “shall not”
recommendation “should” or “should not”
permission “may” or “may not”
capability “can” or “cannot”
1.4 References
For undated references, the most recently published document applies. The most recent WPC
publications can be downloaded from http://www.wirelesspowerconsortium.com.

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1.5 Conventions
1.5.1 Notation of numbers
ƒ Real numbers use the digits 0 to 9, a decimal point, and optionally an exponential part.
ƒ Integer numbers in decimal notation use the digits 0 to 9.
ƒ Integer numbers in hexadecimal notation use the hexadecimal digits 0 to 9 and A to F, and are
prefixed by "0x" unless explicitly indicated otherwise.
ƒ Single bit values use the words ZERO and ONE.
1.5.2 Tolerances
Unless indicated otherwise, all numeric values in the QiSpecification are exactly as specified and do
not have any implied tolerance.
1.5.3 Fields in a data packet
A numeric value stored in a field of a data packet uses a big-endian format. Bits that are more
significant are stored at a lower byte offset than bits that are less significant. Table 2 and Figure 1
provide examples of the interpretation of such fields.
Table 2: Example of fields in a data packet
b b b b b b b b
7 6 5 4 3 2 1 0
(msb)
B
16-bit Numeric Data Field
B
(lsb)
B Other Field (msb)
B 10-bit Numeric Data Field (lsb) Field
Figure 1. Examples of fields in a data packet
16-bit Numeric Data Field
b b b b b b b b b b b b b b b b
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
B B
0 1
10-bit Numeric Data Field
b b b b b b b b b b
9 8 7 6 5 4 3 2 1 0
B B
2 3
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1.5.4 Notation of text strings
Text strings consist of a sequence of printable ASCII characters (i.e. in the range of 0x20 to 0x7E)
enclosed in double quotes ("). Text strings are stored in fields of data structures with the first
character of the string at the lowest byte offset, and are padded with ASCII NUL (0x00) characters
to the end of the field where necessary.
EXAMPLE: The text string “WPC” is stored in a six-byte fields as the sequence of characters 'W', 'P', 'C', NUL,
NUL, and NUL. The text string “M:4D3A” is stored in a six-byte field as the sequence 'M', ':', '4', 'D',
'3', and 'A'.
1.5.5 Short-hand notation for data packets
In many instances, the QiSpecification refers to a data packet using the following shorthand
notation:
/
In this notation, refers to the data packet's mnemonic defined in the QiSpecification,
CommunicationsProtocol, and refers to a particular value in a field of the data packet.
The definitions of the data packets in the QiSpecification,CommunicationsProtocol, list the
meanings of the modifiers.
For example, EPT/cc refers to an End Power Transfer data packet having its End Power Transfer
code field set to 0x01.
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1.6 Power Profiles
A Power Profile determines the level of compatibility between a Power Transmitter and a Power
Receiver. Table 3 defines the available Power Profiles.
ƒ BPPPTx: A Baseline Power Profile Power Transmitter.
ƒ EPP5PTx: An Extended Power Profile Power Transmitter having a restricted power transfer
()pot
capability, i.e. P = 5 W.
L
ƒ EPPPTx: An Extended Power Profile Power Transmitter.
ƒ BPPPRx: A Baseline Power Profile Power Receiver.
ƒ EPPPRx: An Extended Power Profile Power Receiver.
Table 3: Capabilities included in a Power Profile
Feature BPP PTx EPP5 PTx EPP PTx BPP PRx EPP PRx
Ax or Bx design Yes Yes No N/A N/A
MP-Ax or MP-Bx design No No Yes N/A N/A
Baseline Protocol Yes Yes Yes Yes Yes
Extended Protocol No Yes Yes No Yes
Authentication N/A Optional Yes N/A Optional

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2 Introduction
Figure 2 provides a simplified model of a wireless power system, consisting of six blocks. The three
blocks to the left of the power transfer interface represent a Power Transmitter and its supply. The
three to the right represent a Power Receiver and its Load. Typically, these blocks comprise the
following elements.
Supply: in many cases a separate adapter such as a USB PD brick.
Inverter: a half-bridge or full-bridge for DC/AC conversion.
ResonantTank: a coil and series capacitor boosting the power transfer capability.
Rectifier: either a diode bridge or an active (synchronous) bridge for AC/DC conversion.
Load: a power sink drawn by the Power Receiver Product, typically a mobile phone's power input to
an internal battery charger.
Figure 2. Simplified model of a wireless power transfer system
Supply Input Transmitted Received Output Load
Power Power Power Power Power Power
Resonant Resonant
Inverter
Supply Rectifier Load
Tank Tank
PTx Power PRx
Power Transmitter Power Receiver
Input Transfer Output
Interface Interface Interface
With reference to Figure 2, the following definitions are central to the understanding of a wireless
power system.
PowerSignal—An alternating magnetic field.
SupplyPower—The power dissipated from the supply.
PowerTransmitter—A subsystem that can generate a Power Signal.
PowerTransmitterProduct—A device containing one or more Power Transmitters.
TransmittedPower—The power from the Power Signal dissipated by any object that is not an
integral part of the Power Transmitter Product.
PowerReceiver—A subsystem that can extract electric power from a Power Signal.
PowerReceiverProduct—A device containing a Power Receiver.
ReceivedPower—The power from the Power Signal dissipated by any component that is an
integral part of the Power Receiver Product.
TestPowerTransmitter—A Power Transmitter Product designed to analyze and check the
operation of a Power Receiver Product’s wireless power functionality.

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TestPowerReceiver—A Power Receiver Product designed to analyze and check the operation of
a Power Transmitter Product’s wireless power functionality.
LoadPower—The power dissipated in the Load.

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3 Power Receiver construction
Figure 3 illustrates an example of a functional block diagram for a Baseline Power Profile Power
Receiver.
Figure 3. Functional block diagram for a Baseline Power Profile Power Receiver
Power Pick-up Unit
Rectification
Secondary Coil
circuit
Voltage sense
Communications
Communications
modulator
& Control Unit
Output
disconnect
Load
Sensing & control
In this example, the Power Receiver consists of a Power Pick-up Unit and a Communications and
Control Unit. The Power Pick-up Unit on the left-hand side of Figure 3 comprises the analog
components of the Power Receiver:
ƒ A dual resonant circuit consisting of a Secondary Coil plus series and parallel capacitances to
enhance the power transfer efficiency and enable a resonant detection method (see Section
3.1, Dualresonantcircuit).
ƒ A rectification circuit that provides full-wave rectification of the AC waveform using, for
example, four diodes in a full-bridge configuration or a suitable configuration of active
components (see Section 3.2, Rectificationcircuit). The rectification circuit may perform
output smoothing as well. In this example, the rectification circuit provides power to both the
Communications and Control Unit of the Power Receiver and the output of the Power Receiver.

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ƒ A communications modulator (see Section 3.4, Communicationsmodulator). On the DC side of
the Power Receiver, the communications modulator typically consists of a resistor in series
with a switch. On the AC side of the Power Receiver, the communications modulator typically
consists of a capacitor in series with a switch (not shown in Figure 3).
ƒ An output disconnect switch, which prevents current from flowing to the output when the
Power Receiver does not provide power at its output. In addition, the output disconnect switch
prevents current back flow into the Power Receiver when the Power Receiver does not provide
power at its output. Moreover, the output disconnect switch minimizes the power that the
Power Receiver draws from the Power Transmitter when a Power Signal is first applied to the
Secondary Coil.
ƒ A rectified voltage sense.
The Communications and Control Unit on the right-hand side of Figure 3 comprises the digital logic
part of the Power Receiver. This unit executes the relevant power control algorithms and protocols,
drives the communications modulator, controls the output disconnect switch, and monitors several
sensing circuits in both the Power Pick-up Unit and the load. (A good example of a sensing circuit in
the load is a circuit that measures the temperature of a rechargeable battery.)
NOTE: This version of the Specification minimizes the set of Power Receiver design requirements defined in
this section. Accordingly, compliant Power Receiver designs that differ from the sample functional
block diagram shown in Figure 3 are possible. For example, an alternative design includes post-
regulation of the output of the rectification circuit (e.g., by using a buck converter, battery charging
circuit, power management unit, etc.). In yet another design, the Communications and Control Unit
interfaces with other subsystems of the Power Receiver Product, e.g. for user interface purposes.
Figure 4 illustrates an example of a functional block diagram for an Extended Power Profile Power
Receiver. The communications demodulator enables the communication of data from the Power
Transmitter to an Extended Power Profile Power Receiver. The presence of a communications
demodulator is the only difference with the functional block diagram of a Baseline Power Profile
Power Receiver.
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Figure 4. Functional block diagram for an Extended Power Profile Power Receiver
Power Pick-up Unit
Rectification
Secondary Coil
circuit
Voltage sense
Communications modulator
Communications
& Control Unit
Communications demodulator
Output
disconnect
Load
Sensing & control
Power Pick-up Unit components are described in the subsections below.
A Power Receiver design shall include a dual resonant circuit as defined in Section 3.1, Dual
resonantcircuit, a rectification circuit as defined in Section 3.2, Rectificationcircuit, sensing circuits
as defined in Section 3.3, Sensingcircuits, a communications modulator as defined in Section 3.4,
Communicationsmodulator, and an output disconnect switch as defined in Section 3.6, Output
disconnect.
A Power Receiver design for the Extended Power Profile shall also include a communications
demodulator as defined in Section 3.5, Communicationsdemodulator, and shall be able to function
meaningfully if the Power Transmitter restrictions limit the output of power from the Power
Receiver to 5 W; see Section 3.7, Shielding.

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3.1 Dual resonant circuit
The dual resonant circuit of the Power Receiver comprises the Secondary Coil and two resonant
capacitances. The purpose of the first resonant capacitance C is to enhance the power transfer
s
efficiency. The purpose of the second resonant capacitance C is to enable a resonant detection of
d
the receiver position on some Power Transmitter designs.
Figure 5 illustrates the dual resonant circuit. The switch in the dual resonant circuit is optional. If
the switch is not present, the capacitance C shall have a fixed connection to the Secondary Coil L .
d s
If the switch is present, it shall remain closed until the Power Receiver transmits its first Packet
(see the QiSpecification, CommunicationsProtocol).
Figure 5. Dual resonant circuit of a Power Receiver
C
s
C
d
L
s
The dual resonant circuit shall have the following resonant frequencies:
+x
f ′==------------------------------- 100 kHz,
–y
s
2π ⋅ L′ ⋅ C
s s
f==----------------------------------------------------1()000 ±10% kHz.
d
–1
1 1
§·
2π ⋅ L ⋅ ----- + -----
s
©¹
C C
s d
In these equations, L′ is the self-inductance of the Secondary Coil when placed on the Interface
s
Surface of a Power Transmitter and—if necessary—aligned to the Primary Cell; and L is the self-
s
inductance of the Secondary Coil without magnetically active material that is not part of the Power
Receiver design close to the Secondary Coil (e.g. away from the Interface Surface of a Power
Transmitter). Moreover, the tolerances x and y on the resonant frequency f ′ are x = y=5% for
s
Power Receivers that specify a Maximum Power value in the Configuration Packet of 3 W and
above, and x = 5% and y=10% for all other Power Receivers.
NOTE: When determining the capacitance value C , make sure to account for any parasitic capacitances
d
between the terminals of the dual resonant circuit that may affect the resonance frequency value f .
d
The switch shall remain closed even if no power is available from the Secondary Coil.

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The quality factor Q of the loop consisting of the Secondary Coil, switch (if present), resonant
capacitance C and resonant capacitance C , shall exceed the value 77. Here the quality factor Q is
s d
defined as:
2π⋅⋅f L
d s
Q = ------------------------
R
where R is the DC resistance of the loop with the capacitances C and C short-circuited.
s d
Figure 6 shows the environment that is used to determine the self-inductance L′ of the Secondary
s
Coil. The primary Shielding shown in Figure 6 consists of material PC44 from TDK Corp. The
primary Shielding has a square shape with a side of 50 mm and a thickness of 1 mm. The center of
the Secondary Coil and the center of the primary Shielding shall be aligned. The distance from the
Receiver Interface Surface to the primary Shielding is d = 3.4 mm. Shielding on top of the
z
Secondary Coil is present only if the Receiver design includes such Shielding. Other Power Receiver
Product components that influence the inductance of the Secondary Coil shall be present as well
when determining the resonant frequencies. The excitation signal that is used to determine L and
s
L′ shall have an amplitude of 1 V RMS and a frequency of 100 kHz.
s
Figure 6. Characterization of resonant frequencies
Interface
Surface Secondary Coil Shielding (optional)
Mobile
Device
Spacer
d
z
Primary shielding
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3.2 Rectification circuit
The rectification circuit shall use full-wave rectification to convert the AC waveform to a DC power
level.
3.3 Sensing circuits
The Power Receiver shall monitor the DC voltage V directly at the output of the rectification circuit.
r
3.4 Communications modulator
The Power Receiver shall have the means to modulate the Primary Cell current and Primary Cell
voltage as defined in QiSpecification, CommunicationsPhysicalLayer. This version of the
Specification leaves the specific loading method as a design choice to the Power Receiver. Typical
methods include modulation of a resistive load on the DC side of the Power Receiver and modulation
of a capacitive load on the AC side of the Power Receiver.
3.5 Communications demodulator
For the Extended Power Profile, the Power Receiver shall have the means to demodulate frequency-
shift keying (FSK) data from the Power Signal frequency as defined in QiSpecification,
CommunicationsPhysicalLayer. This Specification leaves the specific method up to the designer of
the Power Receiver.
3.6 Output disconnect
The Power Receiver shall have the means to disconnect its output from the subsystems connected
thereto. If the Power Receiver has disconnected its output, it shall ensure that it still draws a
sufficient amount of power from the Power Transmitter, such that Power Receiver to Power
Transmitter communications remain possible (see QiSpecification, CommunicationsPhysical
Layer).
The Power Receiver shall keep its output disconnected until it reaches the powertransfer phase for
the first time after a Digital Ping (see the QiSpecification, CommunicationsProtocol). Subsequently,
the Power Receiver may operate the output disconnect switch any time while the Power
Transmitter applies a Power Signal.
NOTE: The Power Receiver may experience a voltage peak when operating the output disconnect switch
(and changing between maximum and near-zero power dissipation).
Note that the dual resonant circuit as depicted in Figure 5 (in Section 3.1) does not prohibit
implementation of the communications modulator directly at the Secondary Coil.

,(&‹,(& 
3.7 Shielding
An important consideration for a Power Receiver designer is the impact of the Power Transmitter’s
magnetic field on the Power Receiver Product. Stray magnetic fields could interact with the Power
Receiver Product and potentially cause its intended functionality to deteriorate or cause its
temperature to increase due to the power dissipation of generated eddy currents.
It is recommended to limit the impact of magnetic fields by means of Shielding on the top face of
the Secondary Coil (see the QiSpecification,Mechanical,Thermal,andUserInterface for a diagram
of the secondary coil assembly). This Shielding should consist of material that has parameters
similar to the materials listed in the QiSpecification. The Shielding should cover the Secondary Coil
completely. Additional Shielding beyond the outer diameter of the Secondary Coil might be
necessary depending upon the impact of stray magnetic fields.

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4 Power Receiver design guidelines (informative)
4.1 Large-signal resonance check
In the course of designing a Power Receiver, it should be verified that the resonance frequencyf of
s
the dual resonant circuit remains within the tolerance range defined in Section 3.1, Dualresonant
circuit, under large-signal conditions. The test defined in this section serves this purpose.
Step 1. Connect an RF power source to the assembly of Secondary Coil, Shielding and other
components that influence the inductance of the Secondary Coil and series resonant capacitance C ;
s
see Figure 7. The presence of the parallel capacitance C is optional.
d
Figure 7. Large signal secondary resonance test
L
s
Vin
I
in
V
out
C
s
C
d
Step 2. Position the assembly and an appropriate spacer on primary Shielding material, as shown
in Figure 5 (in Section 3.1).
Step 3. Measure the input voltage V as a function of the frequency of the RF power source in the
in
range of 90…110 kHz, while maintaining the input current I at a constant level, preferably at about
in
twice the maximum value intended in the final product.
Step 4. Verify that the frequency at which the measured V is at a minimum, occurs within the
in
specified tolerance range of the resonance frequency f .
s
,(&‹,(& 
4.2 Power Receiver coil design
The mutual inductance M of a Secondary Coil, in combination with optional Shielding and other
Power Receiver Product components, and the Primary Coil of a Power Transmitter design A10
should satisfy the following relations:
V
o
ƒ --------- < 0.8 A , if the Primary Coil and Secondary Coil centers are aligned; and
ωM
V
o
---------
ƒ < 1 A , if the Primary Coil and Secondary Coil centers have a lateral offset of 5 ξ 2 mm.
ωM
Here V is the maximum output voltage expected from the Secondary Coil—or any other voltage
o
that the Power Receiver designer considers relevant—and ω = 2πf , with f = 100 kHz, the
frequency at which the mutual inductance (in units of 1 henry) is measured.

 ,(&‹,(&
5 Power Transmitter construction
5.1 Power Transmitter reference designs
The QiSpecification includes a set of Power Transmitter reference designs that were developed,
tested, and certified by member companies of the Wireless Power Consortium.
5.2 Power transfer control
This version of the Specification, defines a specific method, which the Power Transmitter shall use
to control its Primary Cell current towards the new Primary Cell current (see QiSpecification,
CommunicationsProtocol for a description of the power transfer phases). This method is based on
a discrete proportional-integral-differential (PID) algorithm as illustrated in Figure 8.
Figure 8. PID control algorithm
Control error
message
ሺ ሻ
݆ ,݅
ሺ݆ሻ ܲ 
ܿ
ሺ݆െ1ሻ ሺ ሻ
݆ ,݅
ܭή݁ 
ݐ ήቈ1+ ቉
p
a
ሺ݆ሻ
ݐ

d
ሺ݆ ,݅ሻ
+ +
ሺ ሻ
݆ ,݅ ܲܫܦ 
ሺ݆ ,݅ሻ ሺ݆ ,݅ሻ
ሺ݆ ,݅െ1ሻ ܫ 
ሺ݆ ,݅െ1ሻ
݁ ݒ 
ܫ +
 ݒ െ
Power
ȭ ȭ
ሺ݆ ,݅ሻ
ሺ݆ ,݅ሻ
ܭή݁ ήݐ 
i inner    ܵήܲܫܦ  Conversion Unit
+ v
-
+
ሺ݆ ,݅ሻ
ݐ 
a
ሺ ሻ
݆ ,݅െ1 ሺ݆ ,݅െ1ሻ
ܫ  ݒ 

ሺ ሻ
ሺ ሻ ሺ ሻ ݆ ,݅
݆ ,݅ ݆ ,݅െ1
ܦ
݁ െ݁
ܭ ή
d
ݐ
inner
ሺ݆ ,݅െ1ሻ
ݐ 

a
ሺ ሻ
݆ ,݅െ1
݁

ሺ ሻ
݆െ1
ݐ 

a
Transmitter
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To execute this algorithm, the Power Transmitter shall execute the steps listed below, in the order
of appearance. In the definitions of these steps, the index j = 1, 2, 3, … labels the sequence of Control
Error Packets, which the Power Transmitter receives.
th
ƒ Upon receipt of the j Control Error Packet, the Power Transmitter shall calculate the new
()j
Primary Cell current t as
d
()j
()j ()j – 1 c
t = t ⋅ 1 + ---------
d a
()j – 1
where t represents the actual Primary Cell current—reached in response to the previous
a
(j) th
Control Error Packet—and c represents the Control Error Value contained in the j Control Error
()0
Packet. Note that t represents the Primary Cell current at the start of the powertransferphase.
a
(j)
ƒ If the Control Error Value c is non-zero, the Power Transmitter shall adjust its Primary Cell
current during a time window t . For this purpose, the Power Transmitter shall execute a
active
loop comprising of the steps listed below. The index i = 1, 2, 3, … i labels the iterations of this
max
loop.
à The Power Transmitter shall calculate the difference between the new Primary Cell and
the actual Primary Cell current as the error
()ji, ()j ()ji, – 1
e = t – t
d a
()ji, – 1
where t represents the Primary Cell current determined in iteration i Ϋ 1 of the
a
()j, 0
loop. Note that t represents the actual Primary Cell current at the start of the loop.
a
à The Transmitter shall calculate the proportional, integral, and derivative terms (in any
order):
()ji, ()ji,
P = K ⋅ e
p
()ji, ()ji, – 1 ()ji,
I = I + K⋅⋅e t
i inner
()ji, ()ji, – 1
()ji, e – e
D = K ⋅ ---------------------------------
d
t
inner
where K is the proportional gain, K is the integral gain, K is the derivative gain, and t
p i d inner
is the time required to execute a single iteration of the loop. In addition, the integral term
(j,0) (j,0) (j,i)
I = 0, and the error e = 0. The Power Transmitter shall limit the integral term I
such that it remains within the range ΫM … Ϊ M —if necessary, the Power Transmitter
I I
(j,i)
shall replace the calculated integral term I with the appropriate boundary value.

 ,(&‹,(&
à The Power Transmitter shall calculate the sum of the proportional, integral, and derivative
terms:
()ji, ()ji, ()ji, ()ji,
PID = P ++I D .
(j,i)
In this calculation, the Power Transmitter shall limit the sum PID such that it remains
within the range ΫM … Ϊ M .
PID PID
à The Power Transmitter shall calculate the new value of the controlled variable
()ji, ()ji, – 1 ()ji,
v = v –S ⋅PID ,
v
where S is a scaling factor that depends on the controlled variable. In addition, the
v
()j – 1, i
()j, 0
max (0,0)
controlled variable v = v , with v representing the actual value of the
controlled variable at the start of the powertransferphase, is either the Operating
Frequency, the duty cycle of the inverter, or the voltage input to the inverter. If the
(j,i)
calculated v exceeds the specified range, the Power Transmitter shall replace the
(j,i)
calculated v with the appropriate limiting value.
(j,i)
The Power Transmitter shall apply the new value of the controlled variable v to its
Power Conversion Unit.
à
()ji,
à The Power Transmitter shall determine the actual Primary Cell current t .
a
The maximum number of iterations of the loop i , and the time t required to execute a single
max inner
iteration of the loop shall satisfy the following relation:
i · t = t , with 1 ms ζ t ζ 5 ms
max inner active inner
()j
ƒ The Power Transmitter shall determine the Primary Cell current t exactly at
a
th
t Ϊt Ϊt after the end of the j Control Error Packet.
delay active settle
See the definition of the individual Power Transmitter designs for the values of K , K , K , M ,
p i d I
and M .
PID
,(&‹,(& 
6 Power consumption
In consideration of compliance testing, a Power Receiver shall not drive the Transmitted Power
of Test Power Transmitter #2 above 7500mW with the Power Receiver being positioned on
TPT#2 such that power transfer can be sustained without interruption.

 ,(&‹,(&
7 Meaningful functionality
(Extended Power Profile) If the Power Receiver is not able to negotiate its intended Guaranteed
Load Power level with the Power Transmitter, it shall negotiate a lower Guaranteed Load Power
level, and function meaningfully at that power level. Meaningful functionality includes charging a
connected battery at a rate lower than
...