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ES D1 8V U 1B and E SD 110 -B 1
TV S Diod es in TSL P a nd T S SL P
BDTIC
Tailor ed E SD P rot ec tion f or th e N FC
Fron ten d
Nea r Fi el d C o m mu nic atio n
- Tec hnic al o ve r vie w
- Fr ont en d E S D p ro tec tio n
Applic atio n N ote A N 244
Revision: Rev. 1.2
2014-05-15
RF and P r otecti on D evic es
www.BDTIC.com/infineon
BDTIC
Edition 2014-05-15
Published by
Infineon Technologies AG
81726 Munich, Germany
© 2014 Infineon Technologies AG
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ESD18VU1B and ESD110-B1 TVS Diodes in TSLP and TSSLP
ESD Protection of the NFC Frontend
Application Note AN244
Revision History: 2014-05-15
Previous Revision: prev. Rev. 1.1
Page
Subjects (major changes since last revision)
Adding ESD110-B1
BDTIC
Trademarks of Infineon Technologies AG
AURIX™, C166™, CanPAK™, CIPOS™, CIPURSE™, EconoPACK™, CoolMOS™, CoolSET™,
CORECONTROL™, CROSSAVE™, DAVE™, EasyPIM™, EconoBRIDGE™, EconoDUAL™, EconoPIM™,
EiceDRIVER™, eupec™, FCOS™, HITFET™, HybridPACK™, I²RF™, ISOFACE™, IsoPACK™, MIPAQ™,
ModSTACK™, my-d™, NovalithIC™, OptiMOS™, ORIGA™, PRIMARION™, PrimePACK™, PrimeSTACK™,
PRO-SIL™, PROFET™, RASIC™, ReverSave™, SatRIC™, SIEGET™, SINDRION™, SIPMOS™,
SmartLEWIS™, SOLID FLASH™, TEMPFET™, thinQ!™, TRENCHSTOP™, TriCore™.
Other Trademarks
Advance Design System™ (ADS) of Agilent Technologies, AMBA™, ARM™, MULTI-ICE™, KEIL™,
PRIMECELL™, REALVIEW™, THUMB™, µVision™ of ARM Limited, UK. AUTOSAR™ is licensed by
AUTOSAR development partnership. Bluetooth™ of Bluetooth SIG Inc. CAT-iq™ of DECT Forum.
COLOSSUS™, FirstGPS™ of Trimble Navigation Ltd. EMV™ of EMVCo, LLC (Visa Holdings Inc.). EPCOS™
of Epcos AG. FLEXGO™ of Microsoft Corporation. FlexRay™ is licensed by FlexRay Consortium.
HYPERTERMINAL™ of Hilgraeve Incorporated. IEC™ of Commission Electrotechnique Internationale. IrDA™
of Infrared Data Association Corporation. ISO™ of INTERNATIONAL ORGANIZATION FOR
STANDARDIZATION. MATLAB™ of MathWorks, Inc. MAXIM™ of Maxim Integrated Products, Inc.
MICROTEC™, NUCLEUS™ of Mentor Graphics Corporation. Mifare™ of NXP. MIPI™ of MIPI Alliance, Inc.
MIPS™ of MIPS Technologies, Inc., USA. muRata™ of MURATA MANUFACTURING CO., MICROWAVE
OFFICE™ (MWO) of Applied Wave Research Inc., OmniVision™ of OmniVision Technologies, Inc.
Openwave™ Openwave Systems Inc. RED HAT™ Red Hat, Inc. RFMD™ RF Micro Devices, Inc. SIRIUS™ of
Sirius Satellite Radio Inc. SOLARIS™ of Sun Microsystems, Inc. SPANSION™ of Spansion LLC Ltd.
Symbian™ of Symbian Software Limited. TAIYO YUDEN™ of Taiyo Yuden Co. TEAKLITE™ of CEVA, Inc.
TEKTRONIX™ of Tektronix Inc. TOKO™ of TOKO KABUSHIKI KAISHA TA. UNIX™ of X/Open Company
Limited. VERILOG™, PALLADIUM™ of Cadence Design Systems, Inc. VLYNQ™ of Texas Instruments
Incorporated. VXWORKS™, WIND RIVER™ of WIND RIVER SYSTEMS, INC. ZETEX™ of Diodes Zetex
Limited.
Last Trademarks Update 2011-02-24
www.BDTIC.com/infineon
Application Note AN244, Rev. 1.2
3 / 19
2014-05-15
ESD18VU1B and ESD110-B1 TVS Diodes in TSLP and TSSLP
ESD Protection of the NFC Frontend
List of Content, Figures and Tables
Table of Content
1
Near Field communication - Overview ............................................................................................. 5
2
Current and future applications for NFC devices ........................................................................... 7
3
NFC implementation in the mobile phone ....................................................................................... 8
4
Requirements for proper NFC frontend ESD protection .............................................................. 10
5
Summary ........................................................................................................................................... 13
6
Appendix: TVS diode measurement results in real application .................................................. 14
7
Authors .............................................................................................................................................. 18
BDTIC
List of Figures
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Figure 8
Figure 9
Figure 10
Figure 11
Figure 12
Figure 13
Figure 14
Figure 15
Figure 16
Figure 17
Figure 18
Figure 19
NFC Modules acting as tag/target (passive mode) or acting as initiator/reader (active mode). .......... 5
Time domain RF simulation of the NFC principle. ............................................................................... 6
RF envelope (13.56MHz) @ the primarty res., toggling the secondary res. lossless/lossy. ............... 6
NFC Modules both in active mode (e.g. in a P2P network) ................................................................. 7
Implementation of a NFC module in the mobile phone. ....................................................................... 8
Single ended NFC antenna frontend used in a mobile phone. ............................................................ 9
Differential NFC antenna frontend used in a mobile phone (lower EMI radiation). ............................. 9
Single ended and differential driven transforming EMI filter to reduce the harmonics and to increase
the voltage swing across the resonant antenna circuit. .................................................................... 10
Correct application for a uni-directional TVS diode. ........................................................................... 10
Correct application for a Bi-directional TVS diode. ............................................................................ 11
TLP characteristic of an NFC TVS. .................................................................................................... 12
TLP measurement setup. ................................................................................................................... 13
Breakdown voltage and leakage current characterisation of ESD18VU1B and ESD110-B1
according to their data sheets. ........................................................................................................... 14
Breakdown voltage and leakage current characterisation of ESD18VU1B or ESD110-B1.
Measurement condition: applied voltage is controlled, leakage current is measured. ...................... 14
Circuit structure of application related measurement setup for ESD18VU1B / ESD110-B1. ............ 15
Measurement setup according NFC FE for the ESD18VU1B / ESD110-B1. .................................... 15
Fundamental power H1 and harmonics power H2, H3 for various RF voltage @ TVS diode. .......... 16
Signal waveform direct at the TVS diode for various antenna voltage PART#1 Antenna voltage
(Ch1), TVS diode current Ch2 (voltage @ 10 Ohm res) .................................................................... 16
Signal waveform direct at the TVS diode for various antenna voltage PART#2 Antenna voltage
(Ch1), TVS diode current Ch2 (voltage @ 10 Ohm res) .................................................................... 17
www.BDTIC.com/infineon
Application Note AN244, Rev. 1.2
4 / 19
2014-05-15
ESD18VU1B and ESD110-B1 TVS Diodes in TSLP and TSSLP
ESD Protection of the NFC Frontend
Near Field communication - Overview
1
Near Field communication - Overview
Near Field Communication or NFC, is a short-range high frequency wireless communication technology which
enables the exchange of data between devices over about a 10…20 centimeter distance. The technology is a
simple extension of the ISO/IEC 14443 proximity-card standard (proximity card, RFID) that combines the
interface of a smartcard and a reader into a single device. An NFC device can communicate with both existing
ISO/IEC 14443 smartcards and readers, as well as with other NFC devices, and is thereby compatible with
existing contactless infrastructure already in use for public transportation and payment. NFC is primarily aimed
for usage in mobile phones.
NFC communicates via magnetic field induction, where two loop antennas are located within each other's near
field, forming an air-core transformer (figure 1, figure 2 and figure 4). It operates within the globally available and
unlicensed radio frequency ISM band (Industrial, Scientific and Medical) of 13.56 MHz.
BDTIC
Working distance with compact standard antennas: up to 20 cm.
Supported data rates: 106, 212, 424 kbit/s.
Manchester coding with 10% ASK (Amplitude Shift Keying) modulation rate.
Modified Miller coding with 100% ASK modulation rate.
NFC device can work in passive mode (battery off) and in active mode:
o card emulation: the NFC device behaves like an existing contactless card or RFID tag. The
NFC device is passive and is triggered by an active initiator
NO continous application, only active for a short time frame.
o reader mode: the NFC device (initiator) is active and read a passive RFID tag, for example
for interactive advertising.
o P2P mode: two NFC devices are communicating together and exchanging information. Both
NFC devices has to be in the active mode.
Initiator/Reader
Target/Tag
L_sec
secondary
resonator
13.56MHz
Reverse
magnetic
coupling
bandpass
Data from
target/tag
Forward
magnetic
coupling
L_prim
C_prim
matched EMI filter
primary
resonator
13.56MHz
C_sec





amplifier
ASK
demodulator
Figure 1
NFC Modules acting as tag/target (passive mode) or acting as initiator/reader (active mode).
www.BDTIC.com/infineon
Application Note AN244, Rev. 1.2
5 / 19
2014-05-15
ESD18VU1B and ESD110-B1 TVS Diodes in TSLP and TSSLP
ESD Protection of the NFC Frontend
Near Field communication - Overview
1.1
Passive Communication Mode
The initiator device provides a magnetic carrier field and the NFC device (target) answers by modulating the
existing magnetic field. In this mode, the target device creates its operating power from the initiator provided
electromagnetic field, thus making the Target device a transponder.
This mode is similar to the RFID (Radio Frequency Identification Device) working mode.
The basic principle of this passive mode is the magnetic air coupling between Initiator´s (reader) primary coil
L_prim and the the target coil L_sec on secondary side. Energy is transmitted from L_prim to L_sec and picked
up on the secondary side (target) (forward response). On one hand the received magnetic energy is used to
power the tag, on the other the received magnetic field is modulated. The tag is responding by modulating the
Q-factor of the secondary resonance circuit L_sec/C_sec by switching on and off a shunt resistor according to
the data sequence. This periodic attenuation of the secondary resonance circuit is visible on primary side
(reverse response) and can be detected. The reverse response is reduced by reducing the coupling factor k, as
a result of increasing the distance between the initiator (primary) and the target (secondary).
BDTIC
Figure 2
Time domain RF simulation of the NFC principle.
RF Envelope @
primary side:
Lossless
secondary
resonator
Lossy
secondary
resonator
Initiator / reader
are very close here
Coupling factor k=0.1
Figure 3
RF envelope (13.56MHz) @ the primarty res., toggling the secondary res. lossless/lossy.
www.BDTIC.com/infineon
Application Note AN244, Rev. 1.2
6 / 19
2014-05-15
ESD18VU1B and ESD110-B1 TVS Diodes in TSLP and TSSLP
ESD Protection of the NFC Frontend
Current and future applications for NFC devices
1.2
Active Communication Mode
Running this mode the NFC device can act as an initiator (active reader) to get contact with a passive target.
Two NFC devices can act as initiator and target device and communicate by alternately generating their own
modulated field. A device deactivates its RF field while it is waiting for data. In this mode, both devices typically
need to have a power supply.
Initiator/Reader #1
Initiator/Reader #2
L_sec
matched EMI filter
primary
resonator
13.56MHz
C_sec
Forward
magnetic
coupling
L_prim
C_prim
matched EMI filter
primary
resonator
13.56MHz
BDTIC
Modulation
input
bandpass
Data from #2
Reverse
magnetic
coupling
Modulation
input
bandpass
Data from #1
amplifier
amplifier
ASK
demodulator
ASK
demodulator
Figure 4
NFC Modules both in active mode (e.g. in a P2P network)
2
Current and future applications for NFC devices
Plenty of applications are present in the market yet, or will enter the market soon.


Mobile Commerce:
o Mobile ticketing – for airplanes, for public transport, for concerts/events.
o Mobile payment — the device acts as a debit/ credit payment card.
o Electronic money – like a stored value card.
Proof of Identity
o Access control for buildings, or IT equipment.
o Electronic keys - car keys, house/office keys, hotel room keys, etc.
NFC can be used to configure and initiate other wireless network connections such as Bluetooth, Wi-Fi. The
time consuming configuration procedure for identification to a Bluetooth or WiFi system is reduced by a ―one
touch‖ of two mobiles equipped with NFC devices
To provide the required security level for all these applications, the NFC modem is combined with a secure
controller (NFC module). In a mobile phone the NFC module is also linked to the SIM card.
www.BDTIC.com/infineon
Application Note AN244, Rev. 1.2
7 / 19
2014-05-15
ESD18VU1B and ESD110-B1 TVS Diodes in TSLP and TSSLP
ESD Protection of the NFC Frontend
NFC implementation in the mobile phone
3
NFC implementation in the mobile phone
To provide a highly secure environment especially for mobile commerce, the entire NFC communication has to
be controlled by several security authorities. Therefore the NFC modem is linked to the SIM card and to the
secure controller.
Baseband
ISO
7816
SIM
Application
Processor
BDTIC
SWP (ETSI)
UART/I2C
.…
Secure
Controller
Figure 5
Phone in
Reader Mode
Active
Card Emulation
Passive – Battery Off
NFC Modem
Service Discovery
P2P
Implementation of a NFC module in the mobile phone.
The signal generation and signal extraction is done completely in the NFC modem for the active mode as well
as for the passive mode.
The front-end of the NFC modem includes the mandatory transforming EMI filter and the magnetic loop
antenna. This loop antenna inductor in combination with a capacitance provides the resonance circuit, tuned to
13.56 MHz.
The resonance circuit on primary side (initiator/reader) is coupled to the resonance circuit of secondary side
(NFC modem in passive mode, target/tag). Coupling factor ―k‖ is quite small and depends on the distance
between reader and target.
The inductors L_prim and L_sec on primary and secondary sides work as an air-coupled transformer with k<<1.
The distance between primary and secondary side is within the nearfield of the magnetic field. There is no
conversion from magnetic energy to electrical and back (farfield behavior). Because of the very small antenna in
relation to the wavelength at 13.56 MHZ, the conversion from magnetic near field distribution in an
electromagnetic far field distribution is very weak. This limits the range of an NFC system significant to < 20cm,
even for special equipment to < 10m.
For passive mode (battery off mode) of the NFC module the NFC module is powered by the magnetic field of
the initiator/reader and modulates this information data by switching his 13.56 MHZ resonance circuit between
lossless and lossy mode. The loss of energy in the secondary resonance circuit causes a feedback return to the
primary resonance circuit and drops down the voltage slightly across the primary resonance circuit
(figure 2, figure 3).
This can be detected by an ASK demodulator and a logarithmic amplifier.
For the active mode the NFC modem can work as a (initiator/reader) and collects data from a passive target/tag.
To transmit data from one NFC module to another NFC module in a kind of peer to peer configuration, both
NFC modules has to be in active mode and act as data transmitter and data receiver. In this case the TX signal
is directly ASK modulated.
www.BDTIC.com/infineon
Application Note AN244, Rev. 1.2
8 / 19
2014-05-15
ESD18VU1B and ESD110-B1 TVS Diodes in TSLP and TSSLP
ESD Protection of the NFC Frontend
NFC implementation in the mobile phone
In a mobile phone the NFC frontend is often separated into the TX driver with the EMC filter and RX signal
decoupling and the high impedance 13.56 MHz resonator. The 13.56 MHz resonator includes the loop antenna
(resonator´s inductance) and a parallel capacitor (resonator´s capacitance).
Because of the loop antenna size, the 13.56 MHZ resonance circuit is located often in the bottom shell of the
mobile, which can be removed by the user. An interface is generated inside the NFC frontend which then
becomes ESD critical. A proper ESD protection becomes mandatory to protect the EMI filter and the driver of
the NFC frontend, located on main mobile phone PCB.
single ended antenna
Main PCB / Top shell
Interconnection
top/bottom shell
“external pads”?
Bottom shell
BDTIC
RF=13.56MHz
Vsignal vs. GND<+-18Vp
Figure 6
loop
GND
EMI-LP filter
Antenna
matching
RX
I_res
TX+
GND
TVS diode
bi-directional
U_br ~18…19V
Low cap.type!!!
Linearity!
Loopantenna
~1µH
NFC Module
TX/RX section
TX+
Caps should be high
voltage type to be save
regards the residual
ESD peak
Single ended NFC antenna frontend used in a mobile phone.
differential antenna
Main PCB / Top shell
Interconnection
top/bottom shell
“external pads”?
RF=13.56MHz
Vsignal vs. GND<+-18Vp
+Vsignal vs. -Vsignal <36V!!!
GND
RX
EMI-LP filter
Antenna
matching
GND
loopTVS diode
bi-directional
U_br ~18…19V
Low cap.type!!!
Linearity!
I_res
loop+
TX-
Loopantenna
~1µH
NFC Module
TX/RX section
TX+
Figure 7
Bottom shell
Caps should be high
voltage type to be save
regards the residual
ESD peak
Differential NFC antenna frontend used in a mobile phone (lower EMI radiation).
www.BDTIC.com/infineon
Application Note AN244, Rev. 1.2
9 / 19
2014-05-15
ESD18VU1B and ESD110-B1 TVS Diodes in TSLP and TSSLP
ESD Protection of the NFC Frontend
Requirements for proper NFC frontend ESD protection
Transforming EMI-LP-filter for
single ended antenna matching
TX+
Transforming EMI-LP-filter for
differential antenna matching
loop+
TX+
loop+
TXGND
GND
RX
Figure 8
GND
GND
RX
loop-
Single ended and differential driven transforming EMI filter to reduce the harmonics and to
increase the voltage swing across the resonant antenna circuit.
BDTIC
Besides the high impedance resonant loop antenna other antenna structures are possible. They might have
different requirements for ESD protection. Please contact the local Infineon sales office for assistance.
4
Requirements for proper NFC frontend ESD protection
In single ended and in differential driven antenna frontends, the RF signal (13.56 MHz) @ the resonator can be
up to about +-18Vp vs. GND. Therefore the TVS diode has to be a so called bi-directional type, to be suitable
for a wanted voltage swing of about +18Vp and for -18Vp. A uni-directional TVS diode would clip on negative
voltage swings.
In a single ended antenna frontend, the usable antenna voltage is defined at ―loop+‖ vs. ―GND‖ (e.g. +-18Vp). In
a differential driven frontend, wanted antenna voltage at ―loop+‖ vs. ―loop-― can be e.g. +-36Vpp. Therefore the
wanted antenna voltage in differential driven antenna frontends can be 2 times the antenna voltage of a single
ended system. Furthermore the EMI radiation in a diff. Driven frontend is significant lower.
4.1
Uni-directional TVS diode vs. bi-directional TVS diode
Uni-directional TVS diode:
A uni-directional TVS diode is designed for a wanted signal between ~0V and ―maximum working voltage‖. The
ESD protection capability is granted for a uni-directional diode for positive AND negative ESD strikes in the
same way.
Wanted signal
positive voltage swing!!
Vp < V_maximal working voltage
shunts
positive and negative
ESD strike
~0V
Blocks positive wanted signal
< V_maximal working voltage
Uni-directional TVS diode
Figure 9
for negative wanted signal:
signal is clipped
Correct application for a uni-directional TVS diode.
www.BDTIC.com/infineon
Application Note AN244, Rev. 1.2
10 / 19
2014-05-15
ESD18VU1B and ESD110-B1 TVS Diodes in TSLP and TSSLP
ESD Protection of the NFC Frontend
Requirements for proper NFC frontend ESD protection
Bi-directional TVS diode:
A bi-directional TVS diode is designed for a wanted signal between ―negative maximum working voltage‖ and
―positive maximum working voltage‖. The ESD protection capability is granted for a bi-directional diode for
positive AND negative ESD strikes in the same way.
Wanted signal
positive voltage swing!!
+Vp < +V_maximal working voltage
shunts
positive and negative
ESD strike
~0V
Blocks negative wanted signal
< - V_maximal working voltage
BDTIC
-Vp < -V_maximal working voltage
Bi-directional TVS diode
Blocks positive wanted signal
< + V_maximal working voltage
Figure 10
Correct application for a Bi-directional TVS diode.
4.2
Principles of the transforming EMI filter
In the NFC system, the TX driver (low output impedance of some 10 Ohm) generates a differential 13.56 MHZ
signal between 0V and may be 3V (~3V for a mobile phone application). The shape of this signal locks like a
square wave. This 0V/3V signal is fed to a transforming EMC filter (figure 7). One job of the transforming EMC
filter is to eliminate all harmonics to avoid interference with the GSM masterclock close to 27.12 MHZ. The other
function is to shift up the NFC driver signal to a higher amplitude and impedance level. Impedance level is
moving to about 1k Ohm or more and signal amplitude could become more than 10Vp or even higher at the
resonant 13.56 MHZ antenna.
1) the transformation relation and
2) loss in the transforming EMI filter and in the 13.56 MHZ resonance circuit. But a strong impedance
transformation ratio (to a high voltage swing at the antenna) makes the resonance circuit very
narrowband and very sensitive to parasitic effects or capacitive hand-effect caused by the user.
4.3
ESD requirements
Therefore ―maximum working voltage‖ of the TVS diode has to fit with the maximum peak voltage @ the
13.56 MHZ resonator. Below the ―maximum working voltage‖ / ―trigger voltage‖ the TVS diode is nearly a perfect
―open circuit‖ and is NOT clipping the signal. The leakage current is below the maximum leakage current
specified for the TVS device.
For optimized system ESD protection, the TVS diode´s breakdown voltage should fit to the maximal wanted
signal in the circuit. Increasing the ―maximum working voltage‖ and inherently the ―minimal breakdown voltage‖
will cause a higher clamping voltage in case of an ESD event. This higher clamping voltage means a higher
ESD stress for the EMC filter/NFC modem. So it is always a trade off between actual required ―maximum
working voltage‖ and the desired ESD performance.
Because the ―maximum working voltage‖ is fixed by application, ESD performance optimization is possible only
by minimizing the dynamic resistance (R_dyn) of the TVS diode. The R_dyn is the switch on resistance of a
TVS diode in case of an ESD event. R_dyn should be as small as possible to keep the residual clamping
voltage as small as possible. Optimizing R_dyn requires wide experience in TVS diode development and
semiconductor technique (figure 11).
www.BDTIC.com/infineon
Application Note AN244, Rev. 1.2
11 / 19
2014-05-15
ESD18VU1B and ESD110-B1 TVS Diodes in TSLP and TSSLP
ESD Protection of the NFC Frontend
Requirements for proper NFC frontend ESD protection
4.4
ESD protection in point of RF performance
The ESD protection circuit should not create harmonic distortion to the 13.56 MHZ RF signal. Therefore the TVS
diode has to be linear as much as possible.
The TVS diode´s ―Maximum working voltage‖ has to be high enough to withstand the maximum peak voltage @
the 13.56 MHZ resonator without signal clipping.
The bi-directional TVS diodes ESD18VU1B and ESD110-B1 with a trigger voltage of 20V (min. value) fit
excellent into this application. In point of TVS diode capacitance, both ESD18VU1B and ESD110-B1 show
outstanding 0.3pF (typical capacitance at 1MHz).
4.5
ESD performance in point of residual ESD stress
The residual ESD voltage in case of an ESD strike depends on the TVS diode´s breakdown voltage and on the
diodes´ ―switch on‖ resistance (R_dyn). The dynamic resistance (R_dyn) can be characterised by the TLP
(Transmission Line Pulse), where we feed a short, well defind current pulse through the diode and measure the
clamping voltage across the TVS diode. This clamping voltage is visible to the subsequent circuit and can still
cause a residual ESD stress for the device. The R_dyn for both ESD18VU1B and ESD110-B1 is about
600 mOhm, which is state of the art in this application.
BDTIC
30
NFC-TVS_TLP responce
TLP Current
25
R_dyn:
(U1-U2)/(I1-I2)
20
U1,I1
15
U_breakdown
10
Maximum working voltage
5
vvvoltagevolatge_brea
kdown
0
0
Figure 11
5
10
15
U2,I2
20
25
TLP Voltage
30
35
40
TLP characteristic of an NFC TVS.
www.BDTIC.com/infineon
Application Note AN244, Rev. 1.2
12 / 19
2014-05-15
ESD18VU1B and ESD110-B1 TVS Diodes in TSLP and TSSLP
ESD Protection of the NFC Frontend
Summary
4.6
Attachment:
TLP measurement overview
Measuring TLP voltage accross the DUT
V
V(t)
High Voltage
Pulse Generator
BDTIC
t
Measuring TLP current into the DUT
50 Ohm
I(t)
I
I_TLP
DUT
V_TLP
50 Ohm TLP system
TLP Current (A)
t
TLP pulse length can be from
30nsec to 500nsec (100nsec typ.)
TLP pulse rise time can be
adjusted from 100psec to 10nsec
(300psec typ.)
Sweeping the TLP current to get the
high current I/V TVS diode characteristic
I
I , V
V
TLP Voltage (V)
Figure 12
TLP measurement setup.
5
Summary
ESD protection in the NFC frontend is easy to realize with application tailored TVS diodes. Numerous of basic
conditions have to be addressed.
The Infineon ESD18VU1B and ESD110-B1 are specifically developed for this application. ESD18VU1B and
ESD110-B1 provide the right breakdown voltage in combination with a very low diode capacitance, which keeps
the non-linear distortions very low. Package wise the ESD18VU1B and ESD110-B1 are available in leadless
package, correlating to SMD (EIA) size 0402 (TSLP) and to SMD (EIA) size 0201 (TSSLP).The electrical
parameters of these two diodes in data sheet are identical.
www.BDTIC.com/infineon
Application Note AN244, Rev. 1.2
13 / 19
2014-05-15
ESD18VU1B and ESD110-B1 TVS Diodes in TSLP and TSSLP
ESD Protection of the NFC Frontend
Appendix: TVS diode measurement results in real application
6
Appendix: TVS diode measurement results in real application
6.1
Breakdown voltage and leakage current characterisation of NFC TVS Diodes
BDTIC
Figure 13
Breakdown voltage and leakage current characterisation of ESD18VU1B and ESD110-B1
according to their data sheets.
Current (A)
NFC ESD18VU1B-02LS
1,00E+00
1,00E-01
1,00E-02
1,00E-03
1,00E-04
1,00E-05
1,00E-06
1,00E-07
1,00E-08
1,00E-09
1,00E-10
1,00E-11
1,00E-12
1,00E-13
1,00E-14
DC
DCcharacteristic
characteristicofofESD18VU1B
NFC diode
device
device used
usedfor
for DC
DCand
andRF
RFtests
tests
“trigger voltage” @ 1mA
maximum reverse
working voltage @ 30nA
0
1 2 3 4
5 6 7 8
V-Forced
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
Voltage (V)
Figure 14
Breakdown voltage and leakage current characterisation of ESD18VU1B or ESD110-B1.
Measurement condition: applied voltage is controlled, leakage current is measured.
According to the measurement shown above, the ESD18VU1B / ESD110-B1 diode remains in isolating mode till
~23.5V is reached. Breakdown voltage and trigger voltage are nearly the same (~23.5V) because of very steep
skirt in I/V diagram.
NFC communication is not a continuous working application. Data transmission in the NFC application is
realized in a short timeframe, independently from the NFC module that is working in active mode (self powered
by own battery) or in passive mode (external powered by the reader).
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Application Note AN244, Rev. 1.2
14 / 19
2014-05-15
ESD18VU1B and ESD110-B1 TVS Diodes in TSLP and TSSLP
ESD Protection of the NFC Frontend
Appendix: TVS diode measurement results in real application
6.2
AC characteristic of the TVS diodes under NFC application conditions
50 Ohm RF Gen.
Figure 15
resonant loop antenna
Transforming EMI filter
Z_load
Circuit structure of application related measurement setup for ESD18VU1B / ESD110-B1.
BDTIC

ESD18VU1B or ESD110-B1 located in resonant NFC frontend antenna circuit, adjusted to 13.56 MHZ.

Resonant NFC frontend antenna circuit driven by 50 Ohm signal generator and transforming EMI filter
Antenna impedance
about 1k Ohm
RF Generator
50 Ohm
Impedance
transfoming
low-pass filter
+ loop antenna
Voltage divider 1:195
Z_load
TVS Diode
ESD18VU1B
Spectrum
analyzer
50 Ohm
4700
47
50 => 1k
10
Ch1
Oscilloscope
Ch2
Figure 16
Measurement setup according NFC FE for the ESD18VU1B / ESD110-B1.
To evaluate the AC (RF) characteristic of the ESD18VU1B / ESD110-B1, the TVS diode was characterized in
the NFC like frontend. Breakdown / trigger voltage can be detected by measuring the nonlinearity products
(harmonics) generated by the TVS diode. By exceeding the breakdown voltage of the TVS diode, the TVS diode
starts to become conducting. This results in a kind of ―voltage depending‖ signal amplitude limitation. Signal
peak is affected only, so the signal shape is changing (time domain). The RF voltage (~13.56MHz) across the
TVS diode (and across the resonant antenna) is controlled by the power level of the 50 Ohm generator. All
passive devices including the antenna inductance have to work in linear mode.
In frequency domain the change of the sine-wave shape is visible by an increase of the harmonics, especially
H3 (3 times the fundamental frequency) and H5 (5 times the fundamental frequency).
We run the RF characterisation of ESD18VU1B / ESD110-B1 in:

Frequency-Domain via spectrum analyser (SA).

Time Domain via oscilloscope.
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Application Note AN244, Rev. 1.2
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2014-05-15
ESD18VU1B and ESD110-B1 TVS Diodes in TSLP and TSSLP
ESD Protection of the NFC Frontend
Appendix: TVS diode measurement results in real application
6.2.1
Frequency domain characterisation via spectrumanalyser (SA)
 RF measurements in frequency and time domain with TVS diode
 WITH TVS: Generator power P(H1) @ 13.56MHz
 P(H1_gen) = 23dBm generator (+-24.6Vp at antenna)
P(H1_SA)= -8.0dBm
P(H2_SA)= -69dBm
P(H3_SA)= -50dBm
 P(H1_gen) = 22dBm generator (+-24.4Vp at antenna)
P(H1_SA)= -8.1dBm
P(H2_SA)= -77dBm
P(H3_SA)= -55dBm
 P(H1_gen) = 21dBm generator (+-24.0Vp at antenna)
P(H1_SA)= -8.2dBm
P(H2_SA)= -77dBm
P(H3_SA)= -72dBm
 P(H1_SA) = 20dBm generator (+-21.3Vp at antenna)
P(H1_SA)= -9.2dBm
P(H2_SA)= -80dBm
P(H3_SA)= -83dBm
BDTIC
 ―0.1dB‖ compression point @ ~+24.2Vp / -24.2Vp @ 21.4dBm gen.
 „Hard limiter― @ ~+-25Vp
Figure 17
Fundamental power H1 and harmonics power H2, H3 for various RF voltage @ TVS diode.
6.2.2
Time domain characterisation via oscilloscope
Linear RF
Linear RF
Ch1
Ch1
Ch2
Ch2
P_generator: 20dBm
P_generator: 21.3dBm
NON linearities starts
NON linearities grows
Ch1
Ch1
Ch2
Ch2
P_generator: 21.4dBm
Figure 18
P_generator: 22dBm
Signal waveform direct at the TVS diode for various antenna voltage
Antenna voltage (Ch1), TVS diode current Ch2 (voltage @ 10 Ohm res)
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Application Note AN244, Rev. 1.2
16 / 19
PART#1
2014-05-15
ESD18VU1B and ESD110-B1 TVS Diodes in TSLP and TSSLP
ESD Protection of the NFC Frontend
Appendix: TVS diode measurement results in real application
NON linearities grows fast
NON linearities become
steady state
Ch1
Ch1
Ch2
Ch2
P_generator: 23dBm
P_generator: 24dBm
BDTIC
NON linearities become
steady state
Ch1
Ch2
P_generator: 25dBm
Figure 19
Signal waveform direct at the TVS diode for various antenna voltage
Antenna voltage (Ch1), TVS diode current Ch2 (voltage @ 10 Ohm res)
PART#2
6.2.3
Comparing measurement in frequency- and time domain with DC results
DC (leakage current and breakdown / trigger voltage characteristic) fits exactly with the RF characteristic of
breakdown / trigger voltage evaluated by measuring harmonics and the signal shape.
Harmonics starts to grow up, exceeding the breakdown- / trigger voltage.

For RF (13.56MHz) fully linear characteristic up to ~+24Vp / -24Vp was measured.
Exceeding the so called ―0.1dB‖ compression point @ ~ +24.2Vp / -24.2Vp the diode acts as a very
smooth signal limiter.

Breakdown voltage DC of ~ 23.5V, is very similar to the RF ―0.1dB‖ compression point @ ~ +24.2Vp / 24.2Vp.
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Application Note AN244, Rev. 1.2
17 / 19
2014-05-15
ESD18VU1B and ESD110-B1 TVS Diodes in TSLP and TSSLP
ESD Protection of the NFC Frontend
Authors
7
Authors
Alexander Glas
Infineon Principal Engineer ―RF and Protection Devices‖.
8.
References
Infineon AG - Application Note AN210: « Effective ESD Protection Design at System
Level using VF-TLP Characterization Methodology »
BDTIC
For data sheets and further documents please visit www.infineon.com/ESDprotection
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Application Note AN244, Rev. 1.2
18 / 19
2014-05-15
BDTIC
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Published by Infineon Technologies AG
AN244