IEC 63563-5:2025

Qi Specification version 2.0 - Part 5: Communications Physical Layer

IEC 63563-5:2025 defines the low-level (physical layer and the data link layer) formats of data bits, data bytes, and data packets. In addition, it provides requirements and guidelines for load modulation and frequency-shift keying.

Spécification Qi version 2.0 - Partie 5 : Couche physique des communications

IEC 63563-5:2025 définit les formats de bas niveau (couche physique et couche de liaison de données) des bits de données, des octets de données et des paquets de données. En outre, elle fournit des exigences et des lignes directrices pour la modulation de charge et la modulation par déplacement de fréquence.

General Information

• Status: Published
• Publication Date: 09-Feb-2025
• ICS: 29.240.99 - Other equipment related to power transmission and distribution networks
• ICS: 35.240.99 - IT applications in other fields
• Technical Committee: TA 15 - Wireless Power Transfer
• Drafting Committee: WG 1 - TC 100/TA 15/WG 1
• Current Stage: PPUB - Publication issued
• Start Date: 10-Feb-2025
• Completion Date: 07-Mar-2025

Overview

IEC 63563-5:2025 - Qi Specification version 2.0, Part 5: Communications Physical Layer defines the low‑level communications between a Qi power receiver (PRx) and power transmitter (PTx). Published by IEC in 2025 and based on the Wireless Power Consortium (WPC) Qi v2.0 specification, this standard specifies the physical layer and data link formats for data bits, bytes and packets, and provides requirements and guidelines for load modulation (backscatter) and frequency‑shift keying (FSK) used in wireless power transfer.

Key topics & technical requirements

• Physical & data link layers: Formats and interpretation of data bits, bytes and complete data packets used for PRx→PTx communications.
• Load modulation (backscatter): PRx modulates the power drawn from the primary cell to create two amplitude states (HI and LO). The standard requires detectable amplitude differences; examples in the document include at least 15 mA change in primary cell current or 200 mV change in primary cell voltage. States must be held constant for a minimum specified duration to be valid.
• Frequency‑shift keying (FSK): Defines FSK modulation scheme, bit/byte encoding, and packet structures (see sections on modulation, encoding and response patterns).
• Encoding & packet structure: Big‑endian storage for numeric fields, ASCII printable text strings (0x20–0x7E) padded with NUL (0x00), and shorthand packet mnemonics (e.g., /) for protocol references.
• Compliance language & conventions: Verbal forms (shall/should/may), notation rules for numbers and packet fields, and scope of mandatory vs informative provisions.

Applications & who should use it

• Wireless power system designers (transmitters and receivers) implementing Qi v2.0 communications.
• IC and chipset developers building modulation/demodulation hardware for wireless power.
• Firmware and protocol engineers implementing bit/byte encoding, framing and link‑layer behavior.
• Test labs and conformity assessors validating compliance with Qi communications physical layer requirements.
• Product manufacturers of chargers, mobile devices and accessories integrating Qi wireless power.

Practical value

Adopting IEC 63563-5:2025 ensures interoperable, robust PRx→PTx communications in Qi wireless charging ecosystems. It provides measurable thresholds for reliable detection (current/voltage delta), clear encoding/packet rules, and both load modulation and FSK options - enabling designers to implement interoperable, testable wireless power products.

Related standards

• Qi Specification family (other Qi v2.0 parts such as Communications Protocol, Power Delivery, Mechanical/Thermal documents)
• IEC publications and WPC documents referenced in the Qi specification for interoperability and conformance testing

Keywords: IEC 63563-5:2025, Qi Specification 2.0, Communications Physical Layer, load modulation, frequency‑shift keying, backscatter modulation, wireless power transfer, WPC.

Standards Content (Sample)

IEC 63563-5 ®
Edition 1.0 2025-02
INTERNATIONAL
STANDARD
Qi Specification version 2.0 –
Part 5: Communications Physical Layer

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IEC 63563-5 ®
Edition 1.0 2025-02
INTERNATIONAL
STANDARD
Qi Specification version 2.0 –

Part 5: Communications Physical Layer

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.240.99; 35.240.99 ISBN 978-2-8327-0188-1

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INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
QI SPECIFICATION VERSION 2.0 –
Part 5: Communications Physical Layer
FOREWORD
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not be held responsible for identifying any or all such patent rights.
IEC 635-5 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, Communications Physical Layer 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
which submitted it.
This document was developed in accordance with ISO/IEC Directives, Part 1 and ISO/IEC
Directives, IEC Supplement available at www.iec.ch/members_experts/refdocs. The main
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The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
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
Communications Physical Layer
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: [e-mail].
RELEASE HISTORY
Specification Version Release Date Description
v2.0 April 2023 Initial release of the v2.0 Qi Specification.

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Table of Contents
1  General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1 Structure of the Qi Specification. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.2 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.3 Compliance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.4 References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.5 Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.6 Power Profiles. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2  Load Modulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.1 Modulation scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.2 Bit encoding scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.3 Byte encoding scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.4 Data packet structure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3  Frequency-shift keying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.1 Modulation scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.2 Bit encoding scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
3.3 Byte encoding scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
3.4 Data packet structure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
3.5 Response Pattern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

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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 CommunicationsPhysicalLayer (this document) defines the low-level (physical layer and the
data link layer) formats of data bits, data bytes, and data packets. In addition, it provides
requirements and guidelines for load modulation and frequency-shift keying.
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 Load Modulation
This section defines both the physical layer and the data link layer of the Power Receiver to Power
Transmitter communications interface.
The Power Receiver communicates to the Power Transmitter using backscatter modulation. For
this purpose, the Power Receiver modulates the amount of power that it draws from the Power
Signal. The Power Transmitter detects this as a modulation of the current through and/or voltage
across the Primary Cell. In other words, the Power Receiver and Power Transmitter use an
amplitude modulated Power Signal to provide a Power Receiver to Power Transmitter
communications channel.
2.1 Modulation scheme
The Power Receiver shall modulate the amount of power that it draws from the Power Signal, such
that the Primary Cell current and/or Primary Cell voltage assume two states, namely a HI state and
a LO state. A state is characterized in that the amplitude is constant within a certain variation ȟ for
at least t ms. If the Power Receiver is properly aligned to the Primary Cell of a type A10 or MP-A1
S
Power Transmitter, and for all appropriate loads, at least one of the following three conditions shall
apply:
ƒ The difference of the amplitude of the Primary Cell current in
...