IEC 62368-1
Overvoltage
requirements
Consumer electronics

Datacenter & cloud

Building automation

Appliances

Mobile & wearable

1

IEC 62368-1: Global safety standard applies to wide
range of electrical and electronic equipment up to 600 V
IEC 62368-1*
IEC 60950-1†

IEC 60065†(Information and communication technology
equipment)(Audio/Video and similar electronicequipment)

Point of Sale
equipment

Other equipment‡

Bankingequipment

Office equipment

Telecommunicationequipment

Audio, video equipment, andm usical instruments

Sm art IoTappliances

Battery powered
electronic devices* UL/EN/CSA have created versions of 62368-1 based on IEC 62368-1† Standards replaced by IEC 62368-1 starting in December 2020. All products, sub-assemblies and components previously covered under these standards are covered under UL/IEC 62368-1‡ Other equipment comprises of two product types: ones not covered under any product safety standard such as smart IoT equipment and others covered under various standards such asbattery powered consumer electronic devices

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Minimum transient voltage withstand rating
is determined by the AC mains voltage
Electrical, electronic equipment, and transients

Overvoltage Categorization

Transient voltages are determined based on the system
voltage and where, in a distribution system, the equipment it
is connected (Overvoltage Category)PCs, routers, notebooks, tablets and their power supplies
fall within Overvoltage Category II (see Annex I)Table 12 in section 5.4 defines the following: 120 VAC
power supplies will need to withstand 1500 Vpk; 240 VAC
power supplies need to withstand 2500 Vpk

Overvoltage
Category IV

Overvoltage
Categories III, II, I

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Additional tests included in the standard
to achieve compliance when using varistors
Unreliable earth/ground bond

Reliable earth/ground bond ‡Non-industrial plug examples

Industrial plug examples

Varistor overload test *(Annex G.8.2.2)✓✓

Temporary overvoltage test †(Annex G.8.2.3)✓✓

Basic insulation requirement(Clause 5.4.9.1)✓

Not required

Tests

Table notes: (Detail list of tests provided in supplementary slide)* Test not required if varistor voltage rating is greater than 2 x V R†
Test not required if varistor voltage rating is (1.1 x V R) + 1200 or greater‡ Reliable earth: permanently connected equipment, cord connected mains equipment used in a location having equipotential bonding (restricted access area, telecommunication center and others),
stationary pluggable equipment that has instructions for installation of the conductor to building by a skilled person
Abbreviation:
VR: rated voltage of AC mains or upper voltage of AC mains voltage range

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Solution recommendations for universal
power adapters with two-prong & three-prong plugs
Differential mode protection

Differential & Common mode protection
L

L
I

II
Power
supplycircuit90–240 Vac

DC output
load

Power
supplycircuitN

Product series

Function in application

2153.15*
Fuse

Protects the power stage f rom ov ercurrent ev ents
39213150000

TMOV

III

DC output
load

GTechnology

II

II

III

N

I

I

90–240 Vac

MOV

V10E420P
P2300 + V10E300PTVS DiodeAK3-380C-Y

MOV + GDT

V10E300P + CG3 3.3*

Small, through-hole dev ice with high breaking capacity and high surge
withstand capability

Multiple ampere ratings in compact design

TMOV14RP300E*

SIDACtor® + MOV

Benefits and considerations

Protects the power supply unit f rom v oltage transientsand lightning. Meets minimum allowable MCOV (1.25 x
240 V). Exceeds minimum surge requirements ofOv erv oltage category II

Integrated thermal protection av oids ov erheating caused during
abnormal v oltage ev ents; low energy let-through and clamping v oltage
Smallest f orm-f actor, higher clamping v oltage than other solutions
Lowest leakage current (nA)Best clamping and surge lif e

Protects the power supply unit f rom v oltage transientsand lightning. Meets requirements f or common mode
protection.

Only permitted solution f or common mode protection; lowest
leakage current* This is the primary recommendation. Other products shown can be considered based on design requirements
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Fuse selection▪ Purpose––

Prevent damage due to overcurrent events
Helps pass fault testing▪ Requirements––

Achieves purpose in circuit
Avoids nuisance trips▪ Must not open during normal operation▪ Should not open during surge pulse testing

–
–
–
–

Voltage rating ≥ system voltage
Safely interrupt max available fault current
Fit available space
Meet required 3rd party certifications(e.g. UL, IEC, etc)

215 recommended due to breaking capacity

Item

ExampleSystem215 Series

392 Series

2153.1539213150000

Part #-

Voltage
(Vac)

240

250

250

Current
(A)

0.5

3.15

3.15

Max fault current(A) [1]100

1500

130 [2]I2t [3]
(A2s)

15

43

78

Size [4](mm)-20 x 5.2

8.5 x 4[1] For system, this is determined by equipment design. For fuse, this is the breaking capacity[2] Per UL 248-1 and UL 248-14[3] Pulse I 2t for system. Melting I2t for fuse
[4] Length x Width
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Surge protection requirements: Section 5.5.7▪ Multiple technologies possible(varistors, TVS diodes, protection thyristors, gas discharge
tubes)▪ Varistor & GDT specifically mentioned & most widely used
▪ Varistors––

Allowed between mains and protective earth if ground is reliable
Must comply with G.8

L

N

G

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Clause 5.5.7 SPDs
Examples of non-reliable earthing▪ Loose earth connection inwall socket or damaged
earthing terminal in plug
▪ Plug terminal
reducers/adapters– From 3 terminals to 2 terminals– Essentially removing the groundterminal
Our example, the universal power supply has unreliable ground
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Surge protection requirements: Section 5.5.7▪ Multiple technologies possible(varistors, TVS diodes, protection thyristors, gas discharge
tubes)▪ Varistor & GDT specifically mentioned & most widely used
▪ Varistors–––

Allowed between mains and protective earth if ground is reliable
Must comply with varistor requirements in section G.8
Allowed between line and neutral & between lines (L-N & L-L)

▪ GDTs
–
–

L

L

N

N

G

G

If ground is unreliable; between mains and PE (G), use a varistor
Lwith a GDTComply with Electric strength tests, clearances and creepage
N
distances (sections 5.4.9.1, 5.4.2, and 5.4.3)

Next: select MOV for L-N and MOV+GDT for mains to PE
G

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Select varistors for differential mode protection
according to Annex G.8▪

Comply with a varistor component standard–▪

Example (240 Vac power supply)▪

240 x 1.25 = 300 V

G

Withstand multiple strikes as defined by 2.3.6 of IEC 61051-2 or 8.1.1 of IEC 61643-331–

Example (240 Vac power supply)
▪
▪

▪

N

MCOV ≥ 1.25 x rated voltage of equipment–▪

L

IEC 61051-1 or IEC 61643-331

10 pulses of 2.5 kV / 1.25 kA combination wave of 1.2/50 µs voltage and 8/20 µs current
10 mm* or larger varistor diameter required
R1

Pass varistor overload test (G.8.2.2)––

If used in series with other devices, G.8.2.2 applies to series combination
Example (240 Vac power supply)
▪
▪
▪

–
–

Apply 2x rated voltage = 2 x 240 = 480 V
R1 of test one = 3.84 kΩ
Subsequent tests, halve the R value until circuit opens

300 V thermally protected varistor passes
420 V or higher required for non-thermally protected varistor
▪

480
Vac

MOV or
MOV+GDT

Clamping voltage is higher than 300 V MOV

Recommend 14mm* 300 V TMOV
Note:
* Multiple strike surge may be dif f erent f or specif ic part series. Check manuf acturers spec bef ore f inalizing selection
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Varistor and GDT for common mode protection▪ Varistor (MOV)– Minimum MCOV = 1.25 x rated voltage of equipment▪ Example (240 Vac power supply)–

240 x 1.25 = 300 V– Same surge requirements → 10 mm* MOV (UltraMOV – series)

L▪ Gas Discharge Tube (GDT)
N– Pass electric strength test of 5.4.9.1▪ Withstand voltage of slide 3 (2500 V) → Vbr of GDT ≥ 2500 V– Comply with clearance and creepage of 5.4.2 and 5.4.3▪ MOV and GDTG– Pass overload test from G.8.2.2– Pass temporary over-voltage tests from G.8.2.3– 300 V MOV and 2500 V GDT pass
Recommend 10 mm 300 V MOV and CG33.3 GDT
Note:* Multiple strike surge may be dif f erent f or specif ic part series. Check manuf acturers spec bef ore f inalizing selection
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Surge protection solutions compared
TMOV

MOV

SIDACtor™ + MOVHigh Power TVS
Diode

GDT + MOV

Suggested Protection Modes(When ground is unreliable)

L-L
L-N

L-L
L-N

L-L
L-N

L-L
L-N

L-G & N-G
(Mains to PE)

Continuous voltage w ithstand rating

300 V

420 V

480 V
(180 V + 300 V)

380 V

2940 V(2640 V + 300 V)

Clamping voltage(combination surge: 6 kV/3 kA)

1.18 kV

1.66 kV

1.3 kV*520 V

1.3 kV

Let-through energy during surge event











Leakage current

Medium(μA)

Medium
(μA)

Low
(nA)

Medium(µA)

Very low(pA)

Lifetime after multiple surge events

Good

Fair

Very Good

Excellent

Good

$$

$

$$$

$$$$

$$

Features

PCB footprint surface areaPrice

▪ TMOV recommended for most differential mode protection applications▪ GDT + MOV is the recommended solution between mains and protective earth (per IEC 62368-1, clause 5.5.7)
Note:* Lower clamping is possible with use of a lower voltage MOV and higher rated SIDACtor.
Requires review with agency providing certification to the standard
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Solution recommendations for universal
power adapters with two-prong & three-prong plugs
Differential mode protection

Differential & Common mode protection
L

L
I

II
Power
supplycircuit90–240 Vac

DC output
load

Power
supplycircuitN

Fuse

Product series
2153.15*2153.15

Function in application
Protects the power stage f rom ov ercurrent ev ents

39213150000
TMOV

III

DC output
load

GTechnology

II

II

III

N

I

I

90–240 Vac

TMOV14RP300E*
TMOV14RP300E

MOV

V10E420P

SIDACtor® + MOV

P2300 + V10E300PTVS DiodeAK3-380C-Y

MOV + GDT

V10E300P ++CG3
3.3
V10E300P
CG33.3

Benefits and considerations
Small, through-hole dev ice with high breaking capacity and high surge
withstand capability

Multiple ampere ratings in compact design

Protects the power supply unit f rom v oltage transientsand lightning. Meets minimum allowable MCOV (1.25 x
240 V). Exceeds minimum surge requirements ofOv erv oltage category II

Integrated thermal protection av oids ov erheating caused during
abnormal v oltage ev ents; low energy let-through and clamping v oltage
Smallest f orm-f actor, higher clamping v oltage than other solutions
Lowest leakage current (nA)Best clamping and surge lif e

Protects the power supply unit f rom v oltage transientsand lightning. Meets requirements f or common mode
protection.

Only permitted solution f or common mode protection; lowest
leakage current* This is the primary recommendation. Other products shown can be considered based on design requirements
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Summary▪ IEC 62368-1 superseded IEC 60950-1 and IEC 60065 asof December 2020
▪ Additional tests may apply for compliance▪ IEC 62368-1 can seem complicated at first but allows for
greater safety and design flexibility

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to open the
catalog

Power Supply Spotlight

Additional information can be found on Littelfuse.com

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Application
examples▪ Consumer power supply▪ Industrial power supply

Click on the product series inthe table below for more info

Consumer power supply block diagram1

Input
protection,
rectifier, andfilter2

3
4

High-frequency
converterand clamp

Step-downtransformer

Cable
plug

SeriesFuse215, 392, 443

MOV

UltraMOV, TMOV

GDT *

CG3

TVS diode

P6KE, P6SMB, 8.0SMDJ,
1.5SMB, SMF4L

MOSFET

X2-class

Schottky diode

MBR, DSTPPTC

Low Rho

Digital temperature
indicator **

setP™

2

Feedbackand PWM
oscillator

Legend:Power
Data/Signal

Outputrectificationand filter

1

Technology

3
MCU

4

* GDT in series with MOV is recommended for connection
between L – P.E. or N – P.E. to comply with IEC 62368-1
safety standards.

** setP™ solution is recommended for USB type-C
port protection.

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Click on the product series inthe table below for more info

Industrial power supply block diagram
1
AC
mains

Input
protection,
rectifier,and filter

2
Highfrequency
converterand clamp3
Step-downtransformer

Feedbackand PWM
oscillator

Outputrectificationand filter

SeriesFuse215, 875, 392

MOV

UltraMOV, TMOV

GDT *

CG3

SIDACtor ® + MOV

P2300 + V14E300P

TVS diode

P6KE, P6SMB, 8.0SMDJ,
1.5SMB, SMF4L

MOSFET

X2-class

3

Schottky diode

MBR, DST

4

Fuse

253, 2764
Output DC
protection> 100 W
DC output 1

2
MCU

3

Legend:Power
Data/Signal

Technology

Step-downtransformer

Outputrectificationand filter

Feedbackand PWM
oscillator

MCU< 100 W
DC output* GDT is recommended to be connected in series with TMOV tocomply with the new IEC 62368-1 safety standards.

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Test results▪ Summary of test results▪ TMOV vs. SIDACtor® + MOV▪ Additional test details underIEC 62368

NON-PUBLIC INFORMATION – NDA REQUIRED

Test results summary table
Varistor
overload
test [1]

Surge
Part
protection
descriptions
technology

480 Vac @0.124 to 8 A(current doubled
after each pass)
Test duration:
Till protection
activates

Com bination
Consumer installation oversurge
voltage test[3][2]
test
6KV/3KA (10 hits)
Test duration:
1.2/50 μs (voltage)
8/20 μs (current)

Loss of neutral test [3]1st step
442 Vac @ 1 A

2nd step
255 Vac @ 125A

1st step
442 Vac @ 10 A

2nd step
255 Vac @ 125 A

Test duration:
5s

Test duration:
15 minTest duration:
2 hrs.

Test duration:
15 minSurge-Life
2.5 kV / 1.25
kA
Combinationwave

Rem arks# of Strikes
until 10% Vbr
shift

SIDACtor &MOV

P2300MEL +V14E230P

FAIL

VCLAMP: 0.912
kV

No tests conducted

N/A

230 V MOV not compliant with IEC 62368-1

SIDACtor &MOV

P2300MEL +V10E300PPASS

VCLAMP: 1.3 kVPASS – but not required f or dif f erential mode protection

50

Pass

MOV

V10E420PPASS

VCLAMP: 1.5 kVPASS – but not required f or dif f erential mode protection

15

Pass. Consider f or cost sensitiv e applications

TVS DiodeAK3-380C-Y

N/A[4]VCLAMP: 0.38 kV

Tests not perf ormed since not required f or dif f erential mode protection∞[5]

Pass. Consider if need to handle many surge
ev ents and require f astest clamping f or sensitiv edesigns

TMOV

TMOV14RP300E

PASS

VCLAMP: 1.18 kV

Tests not perf ormed since not required f or dif f erential mode protection

100

PASS: recommended f or dif f erential mode

TMOV

TMOV14RP385E

PASS

VCLAMP: 1.4 kV

PASS

N/A

PASS: but not recommended f or common mode
since standard requires GDT+MOV whenunreliable ground

GDT & MOV

CG3 3.3 +V10E300P

N/A[6]VCLAMP: 1.15 kV
VPeak: 3.6 kV

PASS

∞[7]

Pass: recommended f or common mode

Table notes:
1. Defined in IEC 62368-1 (Annex G.8.2.2)
2. Defined in sections 2.3.6 of IEC 61051-2 or 8.1.1 of IEC 61643-331
3. Defined in IEC 62368-1 (Annex G.8.2.3)
4. TVS Diodes do not need to pass the varistor overload test
5. According to datasheet
6. The test would go on indefinitely, due to the GDT voltage. It would never cause a trip. So the test was not conducted.
7. Due to GDT rating, test value not high enough to cause a trip event so test would continue indefinitely.

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NON-PUBLIC INFORMATION – NDA REQUIRED

Clamping performance compared using 6kV / 3kA
combination wave
Test setup

Comparative test results
Oscilloscope

AC
mains

Isolationtransformer

Surge
generator

Deviceunder
test▪ AC input power is isolated by isolation transformer for protection
during test

▪ Lightning surge generator:– Make: Keytek– Test waveform: 6 kV/3 kA combination wave
▪ Device under test (Littelfuse solution) is subjected to surge wave
from surge generator▪ Clamping voltage across the device is captured by oscilloscope

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NON-PUBLIC INFORMATION – NDA REQUIREDSIDACtor®+ MOV repetitive surge test (2.5 kV/1.25 kA)
Testing mutliple combinations of MOV+SIDACtor
Fresh part

Post 50 cycles▪ P2300MEL + V10E300P repetitive surge test
results:▪ Vbr @ 1 mA: 490 V (fresh part)▪ Vbr @ 1mA: 450 V (post 50 cycles)

Fresh part

Post 80 cycles▪ P3800MEL + V10E230P repetitive surge test
results:▪ Vbr @ 1 mA: 374 V (fresh part)▪ Vbr @ 1mA: 332 V (post 80 cycles)

Fresh part

Post 110 cycles▪ P3800MEL + V10E150P repetitive surge test
results:▪ Vbr @ 1 mA: 258 V (fresh part)▪ Vbr @ 1mA: 226 VConfidential(postand110
cycles)
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NON-PUBLIC INFORMATION – NDA REQUIRED

Measuring let-through energy using various loads
during combination surge (6 kV/3 kA)▪ Lower energy let-through to the load during surge events signifies better protection▪ TMOV provides lowest energy let-through to the load during surge events as shown above withvarious load conditions

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NON-PUBLIC INFORMATION – NDA REQUIRED

Additional tests are required to comply with IEC 62368
Categories

Test procedure

Old standard
UL/EN 60950-1 &UL/EN 60065-1

New standard
EN/UL/CSA 62368-1

Preferred climatic
categories▪
▪
▪

Low er category temperature: –10° C
Upper category temperature: + 85° C
Duration of damp heat, steady state test: 21 days.

✓✓

Maximum continuous
operating voltage(MCOV)▪
▪

At least 1.25 times the rated voltage of the equipment or
At least 1.25 times the upper voltage of the rated voltage range.

✓✓

Surge capability

Combination w ave generator:▪ 10 positive or 10 negative pulses: 1.2/50 μs (voltage) and 8/20 μs (current)▪ Combination pulse of 6 kV/3 kA for equipment connected to 300 V AC mains▪ Combination pulse of 8 kV/4 kA for equipment connected to 600 V AC mains✓✓

Needle flame test

▪
▪
▪
▪

Application of needle-flame on the side surface of VDR
Duration of test: 10 s
After application time: 5 s for extinguishing
If body of VDR complies w ith V-1 material needle-flame test is not needed

✓

✓

▪

Varistor stress test per Annex G.8, allow s for more robust varistor selection
based on it’s voltage rating, size and type (TMOV versus normal MOV)
Apply 2 x VR across DUT starting w ith 0.25 A current and doubling current after
every pass test✓Varistor overload test▪

Temporary overvoltage
test (Surge protection
device)▪
▪
▪

Low voltage system test : Apply temporary overvoltage of 1.32 x Vref for 5 s
Apply temporary overvoltage of 1.74 x Vref for 120 min
DUT can have non-hazardous failure to pass the 120 min test✓

GDT (comply w ith basic
insulation requirement)▪

Solid insulation (per clause 5.4.9.1)

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Littelfuse.com
This document is provided by Littelfuse, Inc. (“Littelfuse”) for informational and guideline purposes only. Littelfuse assumes no liability for errors or omissions in this document orfor any of the information contained herein. Information is provided on an “as is” and “with all faults” basis for evaluation purposes only. Applications described are for illustrative
purposes only and Littelfuse makes no representation that such applications will be suitable for the customer’s specific use without further testing or modification. Littelfuse
expressly disclaims all warranties, whether express, implied or statutory, including but not limited to the implied warranties of merchantability and fitness for a particular purpose,and non-infringement. It is the customer’s sole responsibility to determine suitability for a particular system or use based on their own performance criteria, conditions, specificapplication, compatibility with other components, and environmental conditions. Customers must independently provide appropriate design and operating safeguards to minimize
any risks associated with their applications and products. Read complete Disclaimer Notice at: www.littelfuse.com/disclaimer-electronics.
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