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Transient Protection Transient Protection DevicesDevices

www.microfoundelec.comwww.microfoundelec.com

各种静电及突波保护器件的作用原理及优缺点介绍，

包括二极管，晶闸管，变阻器，气体放电管等。

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Transient EMITransient EMI

�� Most important form of EMIMost important form of EMI

•• ESD (Electrostatic Discharge)ESD (Electrostatic Discharge)

•• EFT/B (Electrical Fast Transient Bursts)EFT/B (Electrical Fast Transient Bursts)

•• Surge (Switching / Lighting induced Surge (Switching / Lighting induced

transient)transient)

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Why Now?Why Now?

�� Digitalized world means trigger by Digitalized world means trigger by

pulse interference easilypulse interference easily

�� The faster devices means more The faster devices means more

sensitivesensitive

�� New generation devices means faster New generation devices means faster

speed and lower operating voltagespeed and lower operating voltage

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Energy of TransientEnergy of Transient�� Energy (Joule)Energy (Joule)

•• Voltage x Current x Pulse widthVoltage x Current x Pulse width

Char.Items

Voltage Current Duration Rise Time Joules

ESD 15kV + 10’s A 10’s ns 100’s ps 1-10’s mJ

EFT/B Several kV 10’s A 10’s ns 10’s ns 10-100’s mJ

Surge Several kV Several kA 10’s us 1’s us 10-100 J

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Protection ConsiderationProtection Consideration�� Voltage allowanceVoltage allowance

�� Current handling capabilityCurrent handling capability

�� Bandwidth ( response )Bandwidth ( response )

�� Loading effectLoading effect

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Equivalent BandwidthEquivalent Bandwidth

�� Fourier transform 40dB/Dec after 1/(Fourier transform 40dB/Dec after 1/(ππTr)Tr)

�� Equivalent to 0.31/Tr (Equivalent to 0.31/Tr (TrTr rising time)rising time)

�� Or, 0.35/Tr Or, 0.35/Tr

•• Ex. 1ns Ex. 1ns TrTr –– 350MHz350MHz

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ESD (EN61000ESD (EN61000--44--2)2)�� The abrupt release of charge that The abrupt release of charge that

has accumulated on a objecthas accumulated on a object

�� Q=CVQ=CV

�� Wave form is function ofWave form is function of

•• Approach speedApproach speed

•• The voltageThe voltage

•• Geometry of electrodeGeometry of electrode

•• Relative humidityRelative humidity

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ESD WaveformESD Waveform

�� ESD output current ESD output current

waveformwaveform

�� TrTr=0.7 to 1ns=0.7 to 1ns

�� Equivalent BW up Equivalent BW up

to several hundred to several hundred

MHzMHz

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Specification of ESDSpecification of ESD

Level

Indicated

voltagekV

First peakcurrent of discharge

±10%A

Rise timewith discharge

switchns

Current(±30%)at 30 ns

A

Current(±30%)at 60 ns

A

1234

2468

7.515

22.530

0.7 to 10.7 to 10.7 to 10.7 to 1

481216

2468

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Spectrum of ESDSpectrum of ESD

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Test of ESDTest of ESDDirest ESDDirest ESD

Contact ESDContact ESD

preferred repeatabilitypreferred repeatability

for metal on EUTfor metal on EUT

Air DischargeAir Discharge

insulating surfaceinsulating surface

discharge from the tip to EUTdischarge from the tip to EUT

tip must approach and touch EUT tip must approach and touch EUT

rapidlyrapidly

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Test of ESDTest of ESD

�� Indirect ESDIndirect ESD

•• VCPVCP

�� To simulate the ESD between the EUT To simulate the ESD between the EUT

and nearby vertical metal objectand nearby vertical metal object

•• HCPHCP

�� To simulate the ESD between the EUT To simulate the ESD between the EUT

and metal deskand metal desk

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Range Of ESD VulnerabilityRange Of ESD Vulnerability

Device TypeDevice Type Range of ESD Range of ESD Vulnerability (v)Vulnerability (v)

MOSFETMOSFET 100 100 -- 200200EPROMEPROM 100 100 -- 3003000P0P--AMPAMP 190 190 -- 25002500CMOSCMOS 250 250 -- 30003000SchottkySchottky DiodeDiode 300 300 -- 25002500Film ResistorsFilm Resistors 300 300 -- 30003000Bipolar TransistorsBipolar Transistors 380 380 -- 70007000SCRSCR 680 680 -- 10001000SchottkySchottky TTLTTL 1000 1000 -- 25002500

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EFT/B (EN61000EFT/B (EN61000--44--4)4)

�� To demonstrate the transient type To demonstrate the transient type

immunity e.g. interruption of immunity e.g. interruption of

inductive loads and relay contact inductive loads and relay contact

bounce. bounce.

�� Defined @ 50ohmDefined @ 50ohm

�� Duration of test not less than 1min.Duration of test not less than 1min.

�� Positive and negative pulsePositive and negative pulse

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Waveform of TestWaveform of Test

�� Source impedance 50ohm Source impedance 50ohm

�� Coaxial outputCoaxial output

�� Test instrument chassis must Test instrument chassis must

connect to GRPconnect to GRP

�� Capacitive clamp is used for Capacitive clamp is used for

data cable.data cable.

�� 1m distance between CDN and 1m distance between CDN and

EUTEUT

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Surge (EN61000Surge (EN61000--44--5)5)

�� The most server disturbance to The most server disturbance to

simulate stress from lightning and simulate stress from lightning and

power switching..power switching..

�� Open circuit voltage with a front time Open circuit voltage with a front time

of 1.2us and half value of 50us.of 1.2us and half value of 50us.

�� Short circuit current with a front time Short circuit current with a front time

of 8us and half value of 20us. of 8us and half value of 20us.

�� Short circuit current from 0.25kA to Short circuit current from 0.25kA to

2.0kA 2.0kA

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Test of SurgeTest of Surge

�� Surge applied at zeroSurge applied at zero--crossing AC crossing AC

voltagevoltage

�� Line to Line (ex. 1kV)Line to Line (ex. 1kV)

�� Line to Ground (ex. 2kV)Line to Ground (ex. 2kV)

�� At least 5 plus and minus voltage @ At least 5 plus and minus voltage @

1/minute1/minute

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Key of Debug (1)Key of Debug (1)

�� Consider the coupling mechanismsConsider the coupling mechanisms

•• ConductedConducted

�� Directly couplingDirectly coupling

�� Common impedanceCommon impedance

•• RadiatedRadiated

CapacitiveCapacitive

InductiveInductive

ElectromagneticElectromagnetic

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Key of Debug (2)Key of Debug (2)

�� High impedance hints capacitive coupling High impedance hints capacitive coupling

dominantdominant

•• Surface areaSurface area

�� Low impedance hints inductive coupling Low impedance hints inductive coupling

dominantdominant

•• Loop areaLoop area

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ProtectionProtection

MOV& MLV

TVSD

ClampingDevices

Gas Tube Thyristor

CrowbarDevices

GT& TVSD

HybridDevices

Capacitor

Filter

ShuntingDevices

PTCNTC

Chokes Fuses

LimitingDevices

Surge ProtectionDevices

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Surge Clamping Of Each DeviceSurge Clamping Of Each Device

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Type of DevicesType of Devices

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ZenerZener DiodeDiode

�� Operated in reverse modeOperated in reverse mode

�� A sharp reverse voltage current A sharp reverse voltage current

transport actiontransport action

�� Low capacitor loading for protecting Low capacitor loading for protecting

circuit.circuit.

�� Protection against over voltageProtection against over voltage

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TVSTVS

�� Transient Voltage Suppressor or Transient Voltage Suppressor or

TransorbsTransorbs

�� Wide clamping voltage range (not Wide clamping voltage range (not

like like ZenerZener diode has very accurate diode has very accurate

voltage specification)voltage specification)

�� Has similar forward and reverse Has similar forward and reverse

characteristic (that means bicharacteristic (that means bi--

direction protection) direction protection)

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TVS DiodeTVS Diode

�� AdvantagesAdvantages

--Low leakage current.Low leakage current.

--Low clamping ratio.Low clamping ratio.

--Fast response.Fast response.

--No degradation until failure mode.No degradation until failure mode.

�� DisadvantagesDisadvantages

--Low surge current handling.Low surge current handling.

--High cost compared with MOVHigh cost compared with MOV

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TVS Diode Structure And Characteristic CurveTVS Diode Structure And Characteristic CurveTVS Diode Structure And Characteristic CurveTVS Diode Structure And Characteristic CurveTVS Diode Structure And Characteristic CurveTVS Diode Structure And Characteristic CurveTVS Diode Structure And Characteristic CurveTVS Diode Structure And Characteristic Curve

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TVS Diode ApplicationTVS Diode Application

�� Power Supply LinesPower Supply Lines

�� Data And Control Lines Data And Control Lines

�� I/O Port I/O Port

�� Reset LinesReset Lines

�� Mechanical or Electrical Switching Mechanical or Electrical Switching

DevicesDevices

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TVS Diode Applications In Power Supply LinesTVS Diode Applications In Power Supply Lines

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TVS Diode Applications In I/O Port And ResetTVS Diode Applications In I/O Port And ResetTVS Diode Applications In I/O Port And ResetTVS Diode Applications In I/O Port And ResetTVS Diode Applications In I/O Port And ResetTVS Diode Applications In I/O Port And ResetTVS Diode Applications In I/O Port And ResetTVS Diode Applications In I/O Port And Reset

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TVS Diode Applications In SMPS Circuit TVS Diode Applications In SMPS Circuit

ProtectionProtection

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Multilayer Multilayer VaristorsVaristors�� Lower clamping level compare with Lower clamping level compare with

same size disc type MOV.same size disc type MOV.

�� Lower voltage than disc type Lower voltage than disc type

available. available.

�� Low capacitance device available.Low capacitance device available.

�� Surface mount.Surface mount.

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ESD Clamped By Multilayer ESD Clamped By Multilayer VaristorVaristor

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Parts Survival Rate At ESD

0

20

40

60

80

100

120

1KV 5KV 10KV 15KV 20KV 25KV

Pie

ces

ceramic cap zener MLV

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Construction Of Multilayer Chip Varistor

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MLV ApplicationsMLV Applications

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MLV And Surge Absorber ApplicationsMLV And Surge Absorber Applications�� DC power lines on the PC boards.DC power lines on the PC boards.

�� I/O lines and their peripherals.I/O lines and their peripherals.

�� IC reset portIC reset port

�� Sensor circuit.Sensor circuit.

�� Keyboard circuitsKeyboard circuits

�� Relay driver circuitsRelay driver circuits

�� Pager speakersPager speakers

�� Antenna circuit and tuner ProtectionAntenna circuit and tuner Protection

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Surge Absorber (Low Cap MLVSurge Absorber (Low Cap MLV))

• Multilayer varistor with Low Capacitance

• Capacitance range from 1 pF to 5 pF

• Surface mount: Sizes are 2012 (0805) and 3216 (1206)

• 0.1 joules of energy handling capability.

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Low Capacitance Surge Absorber ApplicationLow Capacitance Surge Absorber Application

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Metal Oxide Metal Oxide VaristorsVaristors (MOV)(MOV)

�� AdvantagesAdvantages--High surge current handling.High surge current handling.--Fast speed compared with gas tube.Fast speed compared with gas tube.--Less expensive compared with other Less expensive compared with other devices.devices.

�� DisadvantagesDisadvantages--High clamping ratio compared with High clamping ratio compared with

TVSDTVSD

Note: MOV also called voltageNote: MOV also called voltage--dependent ceramic dependent ceramic resistor (VDR)resistor (VDR)

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MOVMOVEpoxy

(94V-0)Disc Material

(Metal Oxide)

Electrode Area (Ag Paste)

Leadwire

(Tin plated copper)

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MOV ApplicationsMOV Applications

�� Power line protection.Power line protection.

�� Telephone line protection.Telephone line protection.

�� Control Line Protection.Control Line Protection.

�� Mechanical contact protection.Mechanical contact protection.

�� Electrical and electronic circuits protectionElectrical and electronic circuits protection

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Selection of MOVSelection of MOV

�� StandbyStandby--state voltage rating state voltage rating

requiredrequired

�� Estimated amount of transient Estimated amount of transient

energy absorbed by the deviceenergy absorbed by the device

�� Expected peak transient currentExpected peak transient current

�� Likely peak power dissipationLikely peak power dissipation

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Residual Voltage Surges Of Connections

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Size of MOVSize of MOV< 7 mm: < 7 mm:

--On PC board protections( <2A).On PC board protections( <2A).

< 14mm: < 14mm:

--AC power input of small size device( < 10A).AC power input of small size device( < 10A).

< 20mm: < 20mm:

--AC power input of medium size device( < 25A). AC power input of medium size device( < 25A).

> 32mm: > 32mm:

--Circuit breaker at building entrances or Circuit breaker at building entrances or

input side of high current devices( >25A)input side of high current devices( >25A)

Note: Current Spec. is for reference onlyNote: Current Spec. is for reference only

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Precise Protection Of Single Phase AC Precise Protection Of Single Phase AC LineLine

2013/11/232013/11/23 4747

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Gas Discharge Tube (GDT)Gas Discharge Tube (GDT)

�� High surge current handlingHigh surge current handling�� Low capacitanceLow capacitance�� Low leakage currentLow leakage current�� Very low capacitance characteristic (<1pf)Very low capacitance characteristic (<1pf)�� Typical operating time in 1us regionTypical operating time in 1us regionHowever,However,�� ItIt’’s response is slows response is slow�� The tube remains in conductive state even The tube remains in conductive state even

after the surge is removed (Holdover)after the surge is removed (Holdover)�� The followThe follow--on current shall be on current shall be

extinguishedextinguished

2013/11/232013/11/23 5050

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Gas Tube Construction

2013/11/232013/11/23 5252

Gas Tube ApplicationsGas Tube Applications

�� Telephone, Data and Control line Telephone, Data and Control line

ProtectionsProtections

�� Coaxial Cable ProtectionCoaxial Cable Protection

�� AC Lines to Ground Protection With High AC Lines to Ground Protection With High

Degree IsolationDegree Isolation

�� Large surge suppression on a low voltage Large surge suppression on a low voltage

lineline•• GDT + TVS or MOVGDT + TVS or MOV

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Gas Tube Application In AC Line IsolationGas Tube Application In AC Line Isolation

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ThyristorsThyristors

�� AdvantagesAdvantages

--High surge current handling compared with High surge current handling compared with

TVS TVS diodes.diodes.

--Offered with lower voltage levels than gas tube.Offered with lower voltage levels than gas tube.

--Fast speed.Fast speed.

--Low leakage. Low leakage.

--No degradation until failure mode.No degradation until failure mode.

�� Disadvantages Disadvantages

--Low surge current handling compared with gas tubeLow surge current handling compared with gas tube

--Higher capacitance than gas tubeHigher capacitance than gas tube

Note: Note: ThyristosThyristos is same as siliconis same as silicon--controlled rectifier (SCR)controlled rectifier (SCR)

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ThyristorThyristor CharacteristicsCharacteristics

Note: Triac is essentially a bi-directional SCR, hence AC signals Pass during both cycles of the waveform

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ThyristorThyristor ApplicationsApplications

�� Secondary protection of the Secondary protection of the

telephone, data and control linestelephone, data and control lines

�� DC power line protectionDC power line protection..

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ThyristorsThyristors In Telecom Line ProtectionIn Telecom Line Protection

2013/11/232013/11/23 5858

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Hybrid ArrestersHybrid Arresters

�� High surge current handlingHigh surge current handling

�� Fast responseFast response

�� Low leakageLow leakage

�� BuiltBuilt--in fail safe mechanismin fail safe mechanism

�� Cost lower than two discrete componentsCost lower than two discrete components

�� Compact size.Compact size.

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Hybrid Arrester ApplicationsHybrid Arrester Applications

�� Primary and secondary protection of the Primary and secondary protection of the

telephone, data and control linestelephone, data and control lines

�� Circuit protection that requires highCircuit protection that requires high

accuracy impulse clampingaccuracy impulse clamping

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COMPARISON OF SUPPRESSOR COMPARISON OF SUPPRESSOR PARAMETERSPARAMETERS

Device Power Speed LeakageDevice Power Speed Leakage Capacitance Capacitance

(8x20uS)(8x20uS) ((nSnS)) ((uAuA)) (pF)(pF)

TVSD ~ 100ATVSD ~ 100A .1.1 < 5< 5 < 500< 500

MOV ~ 9KAMOV ~ 9KA 11 < 20 < 20 < 2000< 2000

MLVMLV ~ 100A~ 100A 11 < 20 < 20 < 200< 200

SB ~ 10A SB ~ 10A 1 < 20 < 11 < 20 < 1

GT ~ 20KAGT ~ 20KA 100100 < .005 < .005 < 2< 2

ThyristorThyristor ~ 250A~ 250A .1.1 < 5< 5 < 500< 500

Hybrid ~10KAHybrid ~10KA .1.1 < 5< 5 < 500< 500

Note: the number is for reference onlyNote: the number is for reference only

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Layout of SuppressorLayout of Suppressor

�� Short and direct connection to the suppressorShort and direct connection to the suppressor

�� The component lead must be short and The component lead must be short and

connected locally to the protected circuitconnected locally to the protected circuit

�� Avoid any common impedance pathAvoid any common impedance path

�� Avoid the flux coupling (keep loop very small)Avoid the flux coupling (keep loop very small)

�� Reservation of the space for suppressor is neededReservation of the space for suppressor is needed

Note: the key is keep inductance minimizedNote: the key is keep inductance minimized

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PolyResetPolyReset

The particle will as changed as temperature The particle will as changed as temperature

changeschanges

Then, the impedance will be changed as well.Then, the impedance will be changed as well.

2013/11/232013/11/23 6565

Benefits of Benefits of PolyResetPolyReset

�� Compared To fusesCompared To fuses

•• Automatic ResetAutomatic Reset

�� Compared To Circuit BreakerCompared To Circuit Breaker

•• No moving parts and Smaller SizeNo moving parts and Smaller Size

�� Compared to Ceramic PTCCompared to Ceramic PTC’’ss

•• Trips 5Trips 5--10 times faster10 times faster

•• Lower initial resistanceLower initial resistance

•• Can withstand higher interrupt currentCan withstand higher interrupt current

•• Smaller size for equivalent deviceSmaller size for equivalent device

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Comparison of PTC CharacteristicsComparison of PTC Characteristics

PTC IntensityPTC IntensityPTC IntensityPTC Intensity

1.0E-01

1.0E+01

1.0E+03

1.0E+05

1.0E+07

1.0E+09

30 50 70 90 110 130 150 170 190

temp

resi

stance

CPTC(Philips)PPTC(CTC)PPTC(Raychem)

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PolyresetPolyreset ApplicationsApplications

�� Telephone Line / UL1459, GR 1089, UL497A ProtectionTelephone Line / UL1459, GR 1089, UL497A Protection

�� Motor protectionMotor protection

�� Transformer and Speaker coil protectionTransformer and Speaker coil protection

�� Lithium Ion Battery protectionLithium Ion Battery protection

Market Driven:

PTC ThermistorRaychemEPCOSMurataBC ComponentsBourns

LFRMMCC-MacCTSBourns

Sidactor (Crowbar)TeccorSTMicroelectronicsPower InnovationsRaychem

Central Office SLIC Schematic (Switch)

Same Customers: CEMs- Lucent, Nortel, Alcatel, NokiaEriccson, Cisco, Fujitsu, Siemens, Others

Plug-In Modules

SSubscribers ubscribers LLine ine IInterface nterface CCards(SLIC) Protectionards(SLIC) Protection

2013/11/232013/11/23 7070

Hybrid ConstructionHybrid Construction

�� RsRs and Ls and Ls

•• provide electrical isolation between devicesprovide electrical isolation between devices

•• To build up sufficient voltage to fire GT & MOVTo build up sufficient voltage to fire GT & MOV

•• Avalanche diode clamps the fast riseAvalanche diode clamps the fast rise--time spike time spike remainedremained

fuse Ls Rs

GT MOV DiodeSupply Load

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Protective Device ComparisonProtective Device Comparison

Device Varistor Zener Clamping diode Gas tube

Range of voltage 12 - 4700 3-200 5-400 90-1000

Tolerance 10 - 25% 5% 10% 20%

Clamp ratio @ 10A

1.85(13J)

1.65 1.25(15J)

2.55

Capacitance(200V)

100-300pF 30pF 30pF 1.2pF

Response time 10-1000ns A few ns <100ns us

Price Medium to low Low Medium Medium

Dissipation capibility (steady

state)

Very low (1/2w for 10J device)

Good to 50W

Good to 10W

Not Applicable

Failure mode Gradual shift in breakdown

Open or short circuit

Short circuit Short

Reference : 1985

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Example of TVSExample of TVS

Spec.Manu.

Peak power Clamping voltage

package Response time

Protek (TVS) 1500W 9.2 – 189V SMD

Protek (TVS) 15000W(1ms)

Modular Sub-ns

General Instrument

(TVS)

5000W(1ms)

6.4 –122V Leaded 1ps

AVX (TVS) 150A @1206 chip

SMD

Reference : 2001

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USB

2013/11/232013/11/23 7474

IEEE1394

2013/11/232013/11/23 7575

Motor

2013/11/232013/11/23 7676

Battery

2013/11/232013/11/23 7777

Ni-Cd / Ni-MH

2013/11/232013/11/23 7878

SCSI

2013/11/232013/11/23 7979

Tuner

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I/O port

2013/11/232013/11/23 8181

Speaker

2013/11/232013/11/23 8282

PBX

2013/11/232013/11/23 8383

Thank you for your attention

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