prEN IEC 63758-4:2026

• Status: Not Published
• Publication Date: 23-Feb-2028
• Technical Committee: CLC/TC 100X - Audio, video and multimedia systems and equipment and related sub-systems
• Current Stage: 4020 - Enquiry circulated - Enquiry
• Start Date: 18-Sep-2026
• Completion Date: 18-Sep-2026
• Directive: 2014/53/EU - Directive 2014/53/EU of The European Parliament and of the Council of 16 April 2014 on the harmonisation of the laws of the Member States relating to the making available on the market of radio equipment and repealing Directive 1999/5/EC
• Mandate: M/607 - COMMISSION IMPLEMENTING DECISION of C(2025)1207 on a Standardisation Request M/607 as regards charging interface and charging communication protocol for radio equipment capable of being recharged by means of wireless charging in relation with Article 3(4), sixth subparagraph, of Directive 2014/53/EU of the European Parliament and of the Council.
• Ref Project: oSIST prEN IEC 63758-4:2026 - Qi specification - Version 2.3 - Part 4: Nfc tag protection (Fast Track)

prEN IEC 63758-4:2026 is a Committee Draft for Vote for the Qi Specification, Version 2.3, Part 4: NFC tag protection (Fast Track), issued through CLC. It specifies how Qi Power Transmitter Products and, where relevant, Power Receiver Products detect Near Field Communication (NFC) tags and Radio Frequency Identification (RFID) tags in the Operating Volume and reduce the risk of damage during wireless power transfer. The document is for engineers, product designers, test labs, and compliance teams working on Qi wireless charging products that also interact with NFC.

What does prEN IEC 63758-4:2026 specify?

prEN IEC 63758-4:2026 covers NFC tag protection within the Qi Specification. Clause 1.2 says the document provides guidance for detecting RFID tags or NFC cards in the Operating Volume of the Power Transmitter and for preventing damage to them.

The document is organized as a general introduction, communication and detection guidance, and a test section, followed by one annex.

Clause or annex	What it covers
1	General rules, compliance language, references, and notation
2	Why NFC tags can be damaged during Qi operation
3	How the Power Receiver Product and Power Transmitter Product coordinate tag protection
4	NFC tag detection by a Power Transmitter Product
5	NFC tag detection by a Power Receiver Product
6	Low-power tag or object detection using the NFC unit
7	TestPICC-based testing of the impact on an NFC tag
Annex A	NDEF records for identifying shielded NFC tags

What are the key requirements of prEN IEC 63758-4:2026?

Compliance language and data conventions

Clause 1.3 sets the meaning of the compliance words used throughout the document: shall and shall not are requirements, should and should not are recommendations, may and may not are permissions, and can and cannot describe capability. In practice, this tells implementers which statements are mandatory and which are design guidance.

Clause 1.5 defines how to read the data. Numeric packet fields use big-endian order, text strings use printable ASCII and NUL padding, and shorthand packet names use the MNEMONIC/modifier form. That matters for firmware and protocol work, because a tag-protection implementation must encode and decode packets exactly as the Qi Specification expects.

Tag protection is part of the Qi safety design

Clause 2 explains the basic risk: a Power Transmitter can damage NFC tags in the Operating Volume, especially during the power transfer phase. The document therefore treats tag protection as a design problem and a measurement problem.

Clause 2.1 says protection can come from adding NFC transceivers to the Power Transmitter Product, the Power Receiver Product, or both. Clause 2.1.2 also says a Power Transmitter can protect NFC tags by keeping magnetic field levels below a defined limit value measured with the TestPICC. In practice, a product team must choose an architecture and then verify that the field levels stay within the permitted range.

The Power Receiver Product and Power Transmitter Product coordinate protection

Clause 3 defines how the Power Receiver Product reacts to the Power Transmitter Product’s extended capability information. The receiver should send a GRQ/xcap packet during negotiation, and the returned XCAP data tells it whether the transmitter supports NFC tag detection or protection.

The XCAP fields TPS, TDE, and TDS drive the receiver’s action. Depending on those values, the Power Receiver Product may detect the tag itself, ask the Power Transmitter Product to do the detection through an EPT/ptxnfc packet, limit power, or stop power transfer with EPT/nfc. In practice, the receiver firmware needs a clear decision tree before it allows full power transfer.

The Power Transmitter Product has several detection architectures

Clause 4 says the Primary Coil cannot be used by the NFC interface because power transfer and NFC use different operating frequencies. It gives three antenna placement options - on top of the Primary Coil, outside the Primary Coil on the shielding, or on the mainboard PCB outside the shielding.

Clause 4.2 then describes two processing models: a separate NFC unit, or shared processing in the Communications and Control Unit (CCU). Clause 4.3 says the transmitter should poll for all common 13.56 MHz technologies and keep polling before and during the ping phase, and in some architectures throughout power transfer. If a tag is detected, the transmitter should return to the ping phase and stay there until the tag is removed. For implementation teams, this section defines the antenna, processor, and polling choices that determine response time and coexistence with the power-transfer field.

The Power Receiver Product can also detect tags

Clause 5 allows the Power Receiver Product to detect NFC tags in the power-transfer Operating Volume. The receiver should align the NFC transceiver Operating Volume with the power-transfer Operating Volume, so the NFC antenna covers the same location as the power-transfer coil.

Clause 5.2 recommends using EPT/rep with the re-ping time packet to force the Power Transmitter Product to remove its power signal, then performing tag detection during re-ping. If a tag is found, the receiver sends EPT/nfc. In practice, this gives receiver-side products a way to protect tags even when transmitter-side detection is limited.

Low-power impedance monitoring can support early detection

Clause 6 describes an NFC unit that monitors antenna impedance. The document presents this as a low-current method for detecting metallic objects or inductively coupled objects such as NFC tags.

The NFC unit can check impedance periodically in standby and during the power transfer phase. If the impedance changes or falls outside the expected range, the unit wakes and runs the NFC tag detection procedure. In practice, this is a low-power alert mechanism that can also support additional Foreign Object Detection (FOD) actions.

Testing uses the TestPICC

Clause 7 defines a Test Proximity Integrated Circuit Card (TestPICC) and uses it to check whether a Power Transmitter Product can damage an NFC tag. The section covers the TestPICC dimensions, construction, calibration, and two test procedures: one for analogue and Digital Ping, and one for power transfer.

For readers, this section is the verification method. It tells test labs how to set up the TestPICC, where to place it, and how to judge whether the transmitter’s field is acceptable for NFC tag protection.

What terms does prEN IEC 63758-4:2026 define?

• Power Transmitter Product (PTx) - The Qi device that sends power and may also include NFC tag detection hardware.
• Power Receiver Product (PRx) - The Qi device that receives power and may also detect NFC tags.
• NFC Mobile Device (NMD) - An NFC-capable mobile device that can emulate a tag and also act as a power receiver.
• Communications and Control Unit (CCU) - The control block that manages Qi behavior and, in shared designs, can also handle NFC processing.
• Test Proximity Integrated Circuit Card (TestPICC) - The WPC test card used to convert NFC field conditions into a measurable DC voltage for protection testing.
• NDEF (NFC Data Exchange Format) - The record format used in Annex A to let shielded NFC tags identify themselves as Qi-friendly.

Who uses prEN IEC 63758-4:2026?

This document is used by Qi product designers, hardware engineers, firmware developers, and system architects who build wireless chargers, receivers, and accessories that also include NFC functions. It is also relevant to test laboratories, certification teams, quality managers, and buyers who need to check whether a product supports NFC tag protection at the transmitter side, the receiver side, or both.

It matters most in consumer electronics where flat-surface Qi systems operate near phones, cards, and other NFC-enabled objects. The document gives those teams a common basis for design, interoperability, and verification.

Which standards are used with prEN IEC 63758-4:2026?

Standard or specification	What it contributes
Qi Specification, Communications Protocol	Defines the packet exchanges and phase behavior referenced by GRQ/xcap, XCAP, and EPT packets
ISO/IEC 14443 series	Background for NFC-A and NFC-B technologies and related activation behavior
NFC Forum Analog, Digital Protocol and Activity specifications	Overview and behavior for NFC polling and technology handling
ISO/IEC 18092	One of the 13.56 MHz NFC-related technologies named for polling
ISO/IEC 15693	Another 13.56 MHz technology used for tag detection and polling
ISO/IEC 18000-3 Mode 3	Another 13.56 MHz technology named for polling
ISO/IEC 10373-6:2016	Basis for the TestPICC calibration procedure and reference card approach
ISO/IEC 14443-1:2016	Used in the calibration relation for the field-strength comparison
NFC Forum technical specifications for NDEF	Provide the NDEF record format used in Annex A

What does the prEN IEC 63758-4:2026 document contain?

The document contains the general rules for reading Qi packet notation, the problem statement for NFC tag damage, and several design paths for transmitter-side and receiver-side protection. It includes antenna placement sketches, CCU and NFC unit integration options, polling logic, and scenarios for distinguishing a physical tag from an NFC Mobile Device.

It also includes a detailed TestPICC section with a circuit, coil layout, calibration procedure, and test methods for analogue and Digital Ping and for power transfer. Annex A adds an example NDEF record approach for shielded NFC tags so they can identify themselves as protected rather than as foreign objects.

SLOVENSKI STANDARD
01-november-2026
Specifikacija Qi - Različica 2.3 - 4. del: Zaščita oznake Nfc (hitri postopek)
Qi specification - Version 2.3 - Part 4: Nfc tag protection (Fast Track)
Ta slovenski standard je istoveten z: prEN IEC 63758-4:2026
ICS:
29.240.99 Druga oprema v zvezi z Other equipment related to
omrežji za prenos in power transmission and
distribucijo električne energije distribution networks
33.160.99 Druga avdio, video in Other audio, video and
avdiovizuelna oprema audiovisual equipment
35.200 Vmesniška in povezovalna Interface and interconnection
oprema equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

100/4542/CDV
COMMITTEE DRAFT FOR VOTE (CDV)
PROJECT NUMBER:
IEC 63758-4 ED1
DATE OF CIRCULATION: CLOSING DATE FOR VOTING:
2026-09-18 2026-12-11
SUPERSEDES DOCUMENTS:
IEC TC 100 : AUDIO, VIDEO AND MULTIMEDIA SYSTEMS AND EQUIPMENT
SECRETARIAT: SECRETARY:
Japan Ms Mahiru Uehara
OF INTEREST TO THE FOLLOWING COMMITTEES: HORIZONTAL FUNCTION(S):
TC 106,TC 108
ASPECTS CONCERNED:
SUBMITTED FOR CENELEC PARALLEL VOTING NOT SUBMITTED FOR CENELEC PARALLEL VOTING
Attention IEC-CENELEC parallel voting
The attention of IEC National Committees, members of
CENELEC, is drawn to the fact that this Committee Draft for
Vote (CDV) is submitted for parallel voting.
The CENELEC members are invited to vote through the
CENELEC online voting system.
This document is still under study and subject to change. It should not be used for reference purposes.
Recipients of this document are invited to submit, with their comments, notification of any relevant patent rights of which they
are aware and to provide supporting documentation.
Recipients of this document are invited to submit, with their comments, notification of any relevant “In Some Countries”
clauses to be included should this proposal proceed. Recipients are reminded that the CDV stage is the final stage for
submitting ISC clauses. (SEE AC/22/2007 OR NEW GUIDANCE DOC).

TITLE:
Qi Specification - Version 2.3 - Part 4: NFC Tag protection (Fast Track)

PROPOSED STABILITY DATE: 2029
NOTE FROM TC/SC OFFICERS:
As this is a fast-track process offered by WPC, the Word file is not provided.

electronic file, to make a copy and to print out the content for the sole purpose of preparing National Committee positions.
You may not copy or "mirror" the file or printed version of the document, or any part of it, for any other purpose without
permission in writing from IEC.

QiSpecification
NFCTagProtection
Version2.3
PublishDate:08December2025
DISCLAIMER
Theinformationcontainedhereinisbelievedtobeaccurateasofthedateofpublication,butisprovided“asis”andmay
containerrors.TheWirelessPowerConsortiummakesnowarranty,expressorimplied,withrespecttothisdocument
anditscontents,includinganywarrantyoftitle,ownership,merchantability,orfitnessforaparticularuseorpurpose.
NeithertheWirelessPowerConsortium,noranymemberoftheWirelessPowerConsortiumwillbeliableforerrorsin
thisdocumentorforanydamages,includingindirectorconsequential,fromuseoforrelianceontheaccuracyofthis
document.Foranyfurtherexplanationofthecontentsofthisdocument,orincaseofanyperceivedinconsistencyor
ambiguityofinterpretation,contact:[e-mail].

Contents
1. General 5
1.1 StructureoftheQi Specification 5
1.2 Scope 6
1.3 Compliance 6
1.4 References 6
1.5 Conventions 7
1.5.1 Notationofnumbers 7
1.5.2 Tolerances 7
1.5.3 Fieldsinadatapacket 7
1.5.4 Notationoftextstrings 8
1.5.5 Short-handnotationfordatapackets 8
2. Introduction 9
2.1 NFCtagdetectionandprotection 9
2.1.1 NFCtagdetection 9
2.1.2 ProtectingNFCtags 10
3. NFCtagprotectionanddevicecommunication 11
4. NFCtagdetectionbyaPowerTransmitterProduct 14
4.1 NFCantennaintegrationinaPowerTransmitterProduct 14
4.1.1 Designoption1:NFCantennaontopofthePrimaryCoil 14
4.1.2 Designoption2:NFCantennaoutsidethePrimaryCoil 15
4.1.3 Designoption3:NFCantennaonthemainboardPCB 15
4.2 NFCtransceiverintegration 15
4.2.1 UsingaseparateNFCunit 15
4.2.2 SharedNFCprocessing 17
4.3 NFCpolling 17
4.3.1 NFCpollingloopinrelationtopowertransferphases 18
4.3.2 NFCMobileDevicesandtags 18
4.3.3 NFCtagdetectionprocedureandscenarios 19
5. NFCtagdetectionbyaPowerReceiverProduct 23
5.1 Designguidelines 23
5.2 Recommendeddetectionprocedure 23
6. TagdetectionusingtheNFCunit 24
6.1 Lowpowerobjectdetectioninstandby 24
6.2 Lowpowerobjectdetectioninthepowertransferphase 24
7. TestingtheimpactofaPowerTransmitterProductonanNFCtag 25
7.1 TestPICCdimensions 25
7.2 ConstructionoftheTestPICC 25
7.3 TestPICCcalibration 28
7.4 TestprocedureusingtheTestPICC 28
7.4.1 TestforAnalogue&DigitalPing 28
7.4.2 Testforpowertransfer 28
AnnexA: UsingNDEF RecordstoidentifyshieldedNFCtags 29
A.1 ExampleNDEFrecord 29
1. General
TheWirelessPowerConsortium(WPC)isaworldwideorganizationthataimstodevelopandpromoteglobalstandards
forwirelesspowertransferinvariousapplicationareas.Animportantapplicationareacomprisesflat-surfacedevices
suchasmobilephonesandchargersoperatingatpowerlevelsupto25W.
1.1 StructureoftheQi Specification
Generaldocuments
l
Introduction
l
Glossary,Acronyms,andSymbols
l
TechnicalSystemOverview
l
PowerProfiles
Systemdescriptiondocuments
l
Mechanical,Thermal,andUserInterface
l
PowerDelivery
l
CommunicationsPhysicalLayer
l
CommunicationsProtocol
l
ForeignObjectDetection
l
NFCTagProtection
l
AuthenticationProtocol
l
MPPCommunicationsProtocol
l
MPPMagneticsDesign
l
MPP PowerDelivery
l
MPP CommunicationsPhysicalLayer
l
MPP ForeignObjectDetection
l
MPP DesignGuidelines(Informative)
l
MagneticCovers
l
ActiveAlignmentSystem
l
ThermalManagementProtocol
1.2 Scope
TheQiSpecification,NFCTagProtection(thisdocument)providesguidelinesfordetectingthepresenceofaRadio
FrequencyIdentification(RFID)tagorNearFieldCommunication(NFC)cardwithintheoperatingrangeofthePower
Transmitterandpreventingdamagetothetagorcard.
1.3 Compliance
AllprovisionsintheQiSpecificationaremandatory,unlessspecificallyindicatedasrecommended,optional,note,
example,orinformative.VerbalexpressionofprovisionsinthisSpecificationfollowtherulesprovidedinISO/IEC
Directives,Part2.
Table1-Verbalformsforexpressionsofprovisions
Provision Verbalform
requirement “shall”or“shallnot”
recommendation “should”or“shouldnot”
permission “may”or“maynot”
capability “can”or“cannot”
1.4 References
Forundatedreferences,themostrecentlypublisheddocumentapplies.ThemostrecentWPCpublicationscanbe
downloadedfromhttp://www.wirelesspowerconsortium.com.

1.5 Conventions
1.5.1 Notationofnumbers
l
Realnumbersusethedigits0to9,adecimalpoint,andoptionallyanexponentialpart.
l
Integernumbersindecimalnotationusethedigits0to9.
l
Integernumbersinhexadecimalnotationusethehexadecimaldigits0to9andAtoF,andareprefixedby"0x"
unlessexplicitlyindicatedotherwise.
l
SinglebitvaluesusethewordsZEROandONE.
1.5.2 Tolerances
Unlessindicatedotherwise,allnumericvaluesintheQiSpecificationareexactlyasspecifiedanddonothaveany
impliedtolerance.
1.5.3 Fieldsinadatapacket
Anumericvaluestoredinafieldofadatapacketusesabig-endianformat.Bitsthataremoresignificantarestoredata
lowerbyteoffsetthanbitsthatarelesssignificant.Table2andFigure1provideexamplesoftheinterpretationofsuch
fields.
Table2-Exampleoffieldsinadatapacket(table)
b b b b b b b b
7 6 5 4 3 2 1 0
B (msb)
B 16-bitNumericDataField (lsb)
B OtherField
(msb)
B 16-bitNumericDataField (lsb)
Field
Figure1-Examplesoffieldsinadatapacket

1.5.4 Notationoftextstrings
TextstringsconsistofasequenceofprintableASCIIcharacters(i.e.intherangeof0x20to0x7E)enclosedindouble
quotes(").Textstringsarestoredinfieldsofdatastructureswiththefirstcharacterofthestringatthelowestbyte
offset,andarepaddedwithASCIINUL(0x00)characterstotheendofthefieldwherenecessary.
EXAMPLE: Thetextstring“WPC”isstoredinasix-bytefieldsasthesequenceofcharacters'W','P','C',NUL,NUL,and
NUL.Thetextstring“M:4D3A”isstoredinasix-bytefieldasthesequence'M',':','4','D','3',and'A'.
1.5.5 Short-handnotationfordatapackets
Inmanyinstances,theQiSpecificationreferstoadatapacketusingthefollowingshorthandnotation:
/
Inthisnotation,referstothedatapacket'smnemonicdefinedintheQiSpecification,Communications
Protocol,andreferstoaparticularvalueinafieldofthedatapacket.Thedefinitionsofthedatapacketsin
theQiSpecification,CommunicationsProtocol,listthemeaningsofthemodifiers.
Forexample,EPT/ccreferstoanEndPowerTransferdatapackethavingitsEndPowerTransfercodefieldsetto0x01.

2. Introduction
APowerTransmittercandamageNearFieldCommunication(NFC)tagspresentintheOperatingVolumeduringany
phaseiftheemittedpowerlevelsareabovethedefinedlimitvalues(seeSection2,Introduction,anditssubsections).
FormoreinformationaboutNFCtags,seehttps://nfc-forum.org/.
Thehighestriskofdamageoccursinthepowertransferphase,asshowninTable3.
Table3-RiskofdamagetoNFCtagsbyprotocol
phase
Protocolphase Riskofdamage
Pingphase Possible
Configurationphase Possible
Negotiationphase Possible
Powertransferphase Likely
2.1 NFCtagdetectionandprotection
ThegoalofthisdocumentistodescribehowNFCtagscanbedetectedandprotectedbyextendingthefunctionalityof
thePowerTransmitterProductand/orPowerReceiverProduct.
2.1.1 NFCtagdetection
ByintegratinganNFCtransceiverintoaPowerTransmitterProductand/orintoaPowerReceiverProduct,anyNFCtag
thatcanbepresentbetweenthePowerTransmitterProductandthePowerReceiverProductcanbedetected.The
capabilitiesofthedevicesdetermineswhichonewillexecuteNFCtagdetection.
l
IfneitherthePowerTransmitterProductnorthePowerReceiverProductcandetectNFCtags,NFCtag
protectiondoesnothappenandanyNFCtagintheOperatingVolumearesusceptibletodamage.
l
IfeitherthePowerTransmitterProductorthePowerReceiverProduct(butnotboth)candetectNFCtags,that
deviceshouldexecutetagdetection.
l
IfboththePowerTransmitterProductandthePowerReceiverProductcandetectNFCtags,oneorbothofthe
devicesshouldexecutetagdetection.
SeeSection3,NFCtagprotectionanddevicecommunication,forfurtherinformation.

2.1.2 ProtectingNFCtags
APowerTransmittercanprotectNFCtagsbymaintainingthemagneticfieldlevelsinallphasesofthepowertransfer
protocolbelowadefinedlimitvalue.ThislimitisdefinedbyspecificmeasurementmethodsusingtheTestProximity
IntegratedCircuitCard(PICC)describedinSection7,TestingtheimpactofaPowerTransmitterProductonanNFCtag,
andhelpstoensurethatNFCtagsarenotdamaged.
NOTE:Inrarecases,damagecanstilloccurevenatmagneticfieldlevelsbelowthelimitvalue.

3. NFCtagprotectionanddevicecommunication
APowerReceivershouldsendaGRQ/xcapdatapackettoanEPPPowerTransmitterduringthenegotiationphaseto
examinethePowerTransmitterProduct’sextendedcapabilities.TheXCAPdatapacketreturnedinresponseprovides
theresultofanyNFCtagdetectionoperationithasexecuted.SeeSection9.5,QiSpecification,CommunicationsProtocol,
formoreinformation.
ThePowerReceiverProductshouldperformoneoftheactionslistedinTable4dependingonvaluescontainedinthe
TPS,TDE,andTDSfieldsoftheXCAPdatapacket.
Table4-PowerReceiveractionsbasedonXCAPdata
XCAPdata XCAPmeaning PowerReceiverProductaction
TPS=ZERO ThePowerTransmitterProductdoes ThePowerReceiverProductshouldperform
notsupportNFCtagdetection. NFCtagdetectionasdefinedinSection5,NFC
tagdetectionbyaPowerReceiverProduct.
TPS=ONE ThePowerTransmitterProduct Thepowertransferproceedsasdefinedinthe
TDE=ONE supportsNFCtagdetectionandhas QiSpecification,CommunicationsProtocol.
TDS=0
notdetectedatag.
TPS=ONE ThePowerTransmitterProduct Toproceed,thePowerReceiverProduct
TDE=ZERO
supportsNFCtagprotectionbuthas shouldselectoneofthefollowingactions:
TDS=0
notexecutedthelatter.
l
SendanEPT/repdatapacketand
performtagdetectionitselfasdefined
inSection5,NFCtagdetectionbya
PowerReceiverProduct
l
SendanEPT/ptxnfcdatapacketto
requestthePowerTransmitterProduct
toperformtagdetection.Thisshould
causethePowerTransmitterProductto
removeitsPowerSignalandperform
NFCtagdetection.
XCAPdata XCAPmeaning PowerReceiverProductaction
TPS=ONE ThePowerTransmitterProduct ThePowerReceiverProductshouldselectone
TDE=ONE supportsNFCtagprotectionandhas ofthefollowingactionstoproceed:
TDS=1
detectedasingletag.
l
SendanEPT/repdatapacketitselfas
NOTE:ThePowerTransmitter
definedinSection5,NFCtagdetection
Productmaynotbeableto
byaPowerReceiverProduct.
distinguishbetweenanNFCtagand
l
Send an EPT/ptxnfc data packet to
theNFCinterfaceofthePower
request the Power Transmitter to
ReceiverProduct.
perform tag detection. This should
causethePowerTransmitterProductto
remove its Power Signal and perform
NFCtagdetection.
l
Proceed to the power transfer phase
andlimititsdrawingthepowerlevelto
5 W.
l
Proceedatfullpowerifitknowsthat
itsownNFCtransceiverisactiveinthe
OperatingVolume.
l
SendanEPT/nfcdatapacketandpower
transferterminates.
NOTE:WheneveranNFCtagispotentiallyinthe
OperatingVolume,thePowerReceiver
Productshouldprovideawarningtothe
user.
TPS=ONE ThePowerTransmitterProduct ThePowerReceiverProductshouldselectone
TDE=ZERO
supportsNFCtagprotectionandhas ofthefollowingactionstoproceed:
TDS=2
detectedmultipletags.
l
SendanEPT/repdatapacketitselfas
NOTE:TDS=2maybemultipleNFC
definedinSection5,NFCtagdetection
tagsoratagandanNMD.
byaPowerReceiverProduct.
l
Send an EPT/ptxnfc data packet to
request the Power Transmitter to
perform tag detection. This should
causethePowerTransmitterProductto
remove its Power Signal and perform
NFCtagdetection.
l
Proceed to the power transfer phase
andlimititsdrawingthepowerlevelto
5 W.
l
Proceedatfullpowerifitknowsthat
itsownNFCtransceiverisactiveinthe
OperatingVolume.
l
SendanEPT/nfcdatapacketandpower
transferterminates.
WheneveranNFCtagispotentiallyinthe
OperatingVolume,thePowerReceiverProduct
shouldprovideawarningtotheuser.

ThefollowinggenericguidelinesapplytoEPPPowerTransmitterProductsforNFCtagdetection.
l
ThePowerTransmitterProductdoesnotdetectNFCtags:IfthePowerTransmitterProductdoesnotdetect
anyNFCtag(TDSis0intheXCAPdatapacket),itshouldproceedwithnormaloperation.
l
ThePowerTransmitterProductdetectsoneNFCtag:WhenaPowerReceiverProductrequestsanXCAPdata
packet,itindicatestothePowerTransmitterthatitsupportsNFCtagprotection.ThePowerTransmittershould
notlimittheNegotiableLoadPowerwhenitdetectsanNFCtag.
IfaPowerReceiverProductdoesnotrequestanXCAPdatapacket,thePowerTransmittermayassumethattheit
doesnotsupportNFCtagprotection.Inthatcase,thePowerTransmittershouldlimittheNegotiableLoadPower
to5 WorbelowtoavoiddamagingthedetectedNFCtag.
l
ThePowerTransmitterProductdetectsmorethanoneNFCtag:ThePowerTransmittershouldlimitthe
NegotiableLoadPowerto5 Worbelow.ThePowerReceiverProductcannotproceedatfullpower.

4. NFCtagdetectionbyaPowerTransmitterProduct
ThemostreliablewaytodetectNFCtagsintheOperatingVolumeistointegrateanNFCtransceiverintothePower
TransmitterProduct.ThetransceiverusestheNFCcommunicationchanneltopollformultipletypesofNFCtags.
Inaddition,anNFCtransceivermayimplementlow-powertagdetectioninordertofulfillowpowerrequirements.For
thispurpose,theNFCtransceivercontinuouslymonitorsitsantenna(seeSection6,TagdetectionusingtheNFCunit).
ThemainbuildingblocksrelevanttoNFCtransceiverintegrationfortagprotectionaretheantenna,theNFCtransceiver
block,andtheNFCpollprofile.Allthreepointsarediscussedinthefollowingsubsections.
4.1 NFCantennaintegrationinaPowerTransmitterProduct
DuetothedifferentoperatingfrequenciesusedforpowertransferandNFCcommunication,thePowerTransmitter
Product’sPrimaryCoilcannotbeusedbytheNFCinterface.Accordingly,thissectionintroducesthreeoptionsforadding
anNFCantennatothePowerTransmitterProduct.AllthreeoptionsenablecoexistencebetweenthePrimaryCoiland
theNFCantenna.
Selectingtheappropriatedesignoptiondependspartlyon:
l
thetargetedOperatingVolume,
l
mechanicalconstraints,and
l
spacerestrictionsonthePCB.
4.1.1 Designoption1:NFCantennaontopofthePrimaryCoil
ThefirstdesignoptionplacestheNFCantennaontopofthePowerTransmitterProduct’sPrimaryCoil,asshownin
Figure2.Thestack-upfromthebottomtotopconsistsofthebottomPCB,theShielding,thePrimaryCoil,andtheNFC
antennaonthetopPCB.
TheNFCantennadesignshouldachieveminimumcouplingwiththePrimaryCoil.Inthiscase,themagneticfield
generatedbythePrimaryCoilandNFCoperationhavelittleimpactoneachother.
Figure2-ExampleofNFCantennaontopofthePrimaryCoil

4.1.2 Designoption2:NFCantennaoutsidethePrimaryCoil
ThesecondantennadesignoptionplacestheNFCantennaontheShieldingoutsidethePrimaryCoil,asshowninFigure
3.Thestack-upfromthebottomtotopconsistsofthePCB,theShielding,andthePrimaryCoil.TheNFCferriteisplaced
ontopoftheShieldingoutsidethePrimaryCoil,andtheNFCantennaisplacedontheouteredgeoftheNFCferrite.
ThegoalofthisdesignistoachieveseparationofthewirelesspowertransferandNFCoperatingfrequenciesbyspatial
separationandShielding.TheNFCferritebendsthedirectionoftheNFCfieldupwardsandshieldstheNFCfieldfrom
thePrimaryCoil.Theadvantageofthisdesignistolimitconstructionheight.However,thespatialdecouplingbetween
NFCantennaandPrimaryCoilmightbelessthanindesignoption1andmayrequiremoreexternalcomponentsfor
filteringviatheantennacouplingcircuit.
Figure3-ExampleofNFCantennaoutsidethePrimaryCoil
4.1.3 Designoption3:NFCantennaonthemainboardPCB
ThethirdantennadesignplacestheNFCantennaonthePCBoutsidetheShielding,asshowninFigure4.Thestack-up
frombottomtotopconsistsofthePCB,theShielding,andthePrimaryCoil.TheNFCantennaislocatedwelloutsideand
belowthePrimaryCoil.IftherearemetallicobjectsunderneaththePCB,NFCferritecanbeplacedunderneaththeNFC
antenna.
Inthisdesign,thepowertransferfieldiswellshapedbytheShielding,whichalsoprovidesgoodShieldingfortheNFC
antenna.ThepowertransferfieldhasonlyaminorimpactonNFCcommunications.
Figure4-ExampleofNFCantennaonthemainboardPCB
4.2 NFCtransceiverintegration
ThereismorethanonewaytointegrateNFCtransceiverfunctionalityinaPowerTransmitterProduct.Forexample,the
NFCtransmitandreceiveunitcanbeadedicatedhardwareblockthatmanagesthe13.56 MHzdataexchange.The
processingofNFCdataandcontroloftheNFCcommunicationlinkcanbeexecutedbythePowerTransmitter’s
CommunicationsandControlUnit(CCU)ordirectlyperformedbyanNFCunit.Bothcasesareintroducedinmoredetail
inthenexttwosubsections.
Fromasystempointofview,theCCUandNFCunitinthePowerTransmitterProductcanrunindependently.Theonly
informationexchangenecessaryisduringtagdetectionontheInterfaceSurfaceofthePowerTransmitterProduc
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