ISO/TR 7637-5:2016

Road vehicles — Electrical disturbances from conduction and coupling — Part 5: Enhanced definitions and verification methods for harmonization of pulse generators according to ISO 7637

ISO/TR 7637-5:2016 proposes extended definitions for pulse generators and verification methods necessary for harmonization of different generators used for pulse testing in accordance to ISO 7637‑2 to ensure the comparability and reproducibility of test results independent on generator types. It presents generator verification results based on current definitions of ISO 7637‑2, which shows significant differences depending on the used generator type and explains the technical background of the variances. ISO 7637-5:2016 is based on ISO 7637-1, ISO 7637-2 and ISO 7637-3.

Véhicules routiers — Perturbations électriques par conduction et par couplage — Partie 5: Amélioration des définitions et des méthodes de vérification pour l'harmonisation des générateurs d'impulsions selon la norme ISO 7637

General Information

• Status: Published
• Publication Date: 27-Oct-2016
• ICS: 43.040.10 - Electrical and electronic equipment
• Technical Committee: ISO/TC 22/SC 32 - Electrical and electronic components and general system aspects
• Drafting Committee: ISO/TC 22/SC 32/WG 3 - Electromagnetic compatibility
• Current Stage: 6060 - International Standard published
• Due Date: 24-Aug-2017
• Completion Date: 28-Oct-2016

Standards Content (Sample)

TECHNICAL ISO/TR
REPORT 7637-5
First edition
2016-11-01
Road vehicles — Electrical
disturbances from conduction and
coupling —
Part 5:
Enhanced definitions and verification
methods for harmonization of pulse
generators according to ISO 7637
Véhicules routiers — Perturbations électriques par conduction et par
couplage —
Partie 5: Amélioration des définitions et des méthodes de vérification
pour l’harmonisation des générateurs d’impulsions selon la norme
ISO 7637
Reference number
ISO/TR 7637-5:2016(E)
©
ISO 2016

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ISO/TR 7637-5:2016(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2016, Published in Switzerland
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www.iso.org
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ISO/TR 7637-5:2016(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Test pulse generator description . 1
4.1 Existing generator description . 1
4.2 Test setups for generator verification . 2
4.2.1 General. 2
4.2.2 Existing verification setups . 2
4.2.3 Extended verification setups . 4
4.3 Generator verification . 5
4.3.1 General. 5
4.3.2 Verification results with existing setup definitions . 6
4.3.3 Verification results with extended setup definitions . 8
4.4 Verification summary — Missing generator definitions leading to different results .10
5 Proposal of extended definitions for pulse generators and verification methods .11
5.1 General .11
5.2 Test procedure adaptation .11
5.3 Tolerance definition for generator evaluation .11
5.4 Extended generator definition .11
5.4.1 Decoupling network . .11
5.4.2 Coupling network .12
5.5 Generator models for simulation .13
Annex A (informative) Investigation summary of existing pulse generators.14
Bibliography .40
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ISO/TR 7637-5:2016(E)

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment,
as well as information about ISO’s adherence to the World Trade Organization (WTO) principles in the
Technical Barriers to Trade (TBT) see the following URL: www.iso.org/iso/foreword.html.
The committee responsible for this document is ISO/TC 22, Road vehicles, Subcommittee SC 32, Electrical
and electronic components and general system aspects.
A list of all parts in the ISO/TR 7637 series can be found on the ISO website.
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ISO/TR 7637-5:2016(E)

Introduction
Pulses in vehicles are generated by different switching events of electrical loads connected to the supply
system and coupled via the wiring harness to other components or wires. For test purpose, these pulse
phenomena are simulated by pulse generators and coupled via coupling structures to the wiring of a
device under test. The test pulses are not real pulses but representatives for the wide range of pulse
shapes, amplitudes, source resistances and pulse energy observed in vehicles. The definition of the test
pulses and the coupling structures are described in ISO 7637-1, ISO 7637-2 and ISO 7637-3. Based on the
standard definition, test equipment has been developed and is commercially available.
The experience with existing test equipment shows some difficulties in terms of result reproducibility
for the same DUT dependent on the used generator, which is caused by different realization of test
generators coupling and decoupling networks. The intention of this document is to describe the
background for these variances and to define methods for harmonization of different generator
behaviour.
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TECHNICAL REPORT ISO/TR 7637-5:2016(E)
Road vehicles — Electrical disturbances from conduction
and coupling —
Part 5:
Enhanced definitions and verification methods for
harmonization of pulse generators according to ISO 7637
1 Scope
This document proposes extended definitions for pulse generators and verification methods necessary
for harmonization of different generators used for pulse testing in accordance to ISO 7637-2 to ensure the
comparability and reproducibility of test results independent on generator types. It presents generator
verification results based on current definitions of ISO 7637-2, which shows significant differences
depending on the used generator type and explains the technical background of the variances.
This document is based on ISO 7637-1, ISO 7637-2 and ISO 7637-3.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http://www.electropedia.org/
— ISO Online browsing platform: available at http://www.iso.org/obp
3.1
device under test
DUT
one single component or a combination of components as defined to be tested
3.2
ground plane
GP
flat conductive surface whose potential is used as a common reference
Note 1 to entry: Where applicable, the test voltage should also be referenced to the ground plane.
4 Test pulse generator description
4.1 Existing generator description
The main parts of pulse generators are the pulse shaping and coupling networks, (important for
generating and applying the test pulses to the DUT) and the decoupling network (important for
protecting the connected power supply and effecting the pulse coupling to DUT). A block diagram is
shown in Figure 1.
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ISO/TR 7637-5:2016(E)

Key
1 power supply
2 decoupling network
3 pulse shaping and coupling network
4 DUT (or verification load)
Figure 1 — Pulse generator principle
The generator description in the current edition of ISO 7637-2 defines only: “The test pulse generator
shall be capable of producing the open circuit test pulses described in 5.6.1 to 5.6.4 at the maximum
value of |U |. U shall be adjustable within the limits given in Tables 2 to 6. The timing (t) tolerances and
s s
internal resistance (R ) tolerance shall be ±20% unless otherwise specified.”
i
Beyond that, only timing diagrams of the open circuit voltage and the internal resistor are defined.
4.2 Test setups for generator verification
4.2.1 General
The test setup for generator verification is intended to represent typical load conditions applied to the
test generator out of the infinite range of test applications. For the different setups, the test generator is
expected to show a linear behaviour without resonance effects, under- or over-swing effects. The setup
is defined to evaluate relevant data of the test generator with minimal effect to the tolerance scheme of
the complete test environment.
4.2.2 Existing verification setups
The actual test setup and generator verification procedure are described in ISO 7637-2:2011, Annex C
and limits the verification to open and matched termination with resistive load (load resistor equal to
generator internal pulse source impedance) as shown in Table 1 and Figure 2.
The verification defines and requires
— U = 0 V,
a
— open load condition with
— 10 % magnitude tolerance for pulses 1, 2a, 3a, 3b,
— 20 % of duration for pulses 1, 2a and 30 % duration for pulses 3a, 3b,
— matched load condition with
— 20 % tolerance of magnitude for pulses 1, 2a, 3a, 3b,
— 20 % of duration for pulses 1, 2a and 30 % duration for pulses 3a, 3b,
— matching load resistor with 1 % tolerance.
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ISO/TR 7637-5:2016(E)

Table 1 — Test pulse 1 parameters
Test pulse 1 (Nominal 12 V system)
Test pulse 1 V t t
s r d
No load -100 V ± 10 V 2 000 μs ± 400 μs
0
 
   1 μs
 
− 05,
 
10Ω load -50 V ± 10 V — 1 500 μs ± 300 μs
Test pulse 1 (Nominal 24 V system)
Test pulse 1 V t t
s r d
No load -600 V ± 60 V 1 000 μs ± 200 μs
0
 
   3 μs
 
− 15,
 
50Ω load -300 V ± 60 V — 1 000 μs ± 200 μs
Key
1 oscilloscope or equivalent
2 voltage probe
3 test pulse generator with internal resistance R
i
4 DUT disconnected
5 ground plane
6 ground connection; maximum length for test pulse 3 is 100 mm
Figure 2 — Generator verification setup
In addition, ISO 7637-2:2011, Annex D provides equations for voltage, current and energy calculation of
a simple RC discharging network, consisting of a storage capacitor, internal and external resistor.
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ISO/TR 7637-5:2016(E)

With these setup and tolerance definitions, all existing pulse generators can be verified successfully. But
the limited definitions and wide tolerances lead to different test results with different test generators
and especially under load conditions as described in 4.3.3 and Annex A.
Resonances and nonlinear behaviour of test generators, occurring when a real DUT is connected and
powered via the pulse generator, cannot be detected with the existing verification method. Hence, more
detailed definitions of pulse shaping, coupling and decoupling network and an enhanced verification
definition are necessary.
4.2.3 Extended verification setups
Extended verification setups represent a wider range of application load impedances. These may
be expected in real applications and enable to determine the available power. Based on the existing
verification setup, an extended set of termination impedances is defined and the pulses are described
with closer tolerances.
The following set of verification impedances is defined in Table 2:
— open load conditions;
— matched resistor to generator source impedance;
— low resistive load to simulate applications with high current consumption;
— resistive-capacitive load, to simulate low power loads (e.g. sensors).
This set of termination networks define the relevant values for the frequency spectra of the pulses.
Table 2 — Generator verification condition and load definition
Supply Load 1 2a 3a 3b
unsupplied open load defined defined defined defined
matched load defined defined defined defined
U = 0 V
a
open load — new tbd tbd
matched load — new tbd tbd
supplied
U = U
a N
1Ω new new — —
100nF||1kΩ new new — —
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ISO/TR 7637-5:2016(E)

An enhanced generator verification setup is described in Figure 3.
Key
1 oscilloscope or equivalent
2 voltage probe
3 test pulse generator with internal resistance R
i
4 verification load
5 ground plane
6 ground connection; max. length for test pulse 3 is 100 mm
7 battery or power supply
Figure 3 — Enhanced generator verification setup
4.3 Generator verification
4.3.1 General
The performances of 16 pulse generators, specified for pulse immunity test according to ISO 7637, have
been verified in order to check the compliance with the standard and the behaviour under real test
conditions with supply and typical loads.
In the first step, the test setups for generator verification defined in ISO 7637 were used and the
compliance with the specification was checked. In the second step, the generator input was connected
to a power supply and the pulse generator output was loaded with different load impedances as given by
real devices under test (DUT). In both setups, the pulse waveform and the specified pulse parameters
were monitored.
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ISO/TR 7637-5:2016(E)

4.3.2 Verification results with existing setup definitions
For verification of the compliance with the standardized values, the maximal pulse voltage and the pulse
width at three different test levels for pulse 1 were measured and the deviation to the standardized
value was evaluated. Table 3 shows the verification results.
Table 3 — Generator verification result summary pulse 1
Pulse voltage U deviation % Pulse width t deviation %
s d
Generator
Supply
voltage
Test-pulse Load U standard t standard
s d
U
a
U
s
(min/max) (min/max) (min/max) (min/max)
ISO pulse 1
open-load no open −100 V −100 V ± 10 V ±10 % 2 ms ± 0,4 ms ±20 %
a
definition
5,0 % 6,1 %
result no open −50 V −56 V/−45 V 1,8 ms/2,3 ms
(−9,4 %/+12,5 %) (−10 %/+15 %)
3,5% 5,4 %
a
result no open −100 V −109 V/−93 V 1,9 ms/2,2 ms
(−6,3 %/+9,2 %) (−5 %/+10 %)
3,5 % 5,5 %
result no open −150 V −142 V/−164 V 1,9 ms/2,2 ms
(−5,2 %/+9,1 %) (−5 %/+10 %)
ISO pulse 1
10Ω-load no 10Ω −100 V −50 V ± 10 V ±20 % 1,5 ms ± 0,3 ms ±20 %
a
definition
3,3 % 5 %
result no 10Ω −50 V −25 V/−22 V 1,4 ms/1,6 ms
(−5,8 %/+4,6 %) (−6,7 %/+6,7 %)
3,6 % 4,1 %
a
result no 10Ω −100 V −52 V/−46 V 1,3 ms/1,5 ms
(−6,8 %/+5,5 %) (−13,3 %/0 %)
4,4 % 3,9 %
result no 10Ω −150 V −80 V/−70 V 1,3 ms/1,5 ms
(−6,9 %/7,5 %) (−13,3 %/0 %)
a
Values to be verified according to ISO 7637-2 definition.
The standard deviation of the pulse voltage over all generators for pulse 1 for three levels −50 V, −100 V
and −150 V varies between 3,5 % and 5 % for open load conditions. The maximal deviation increases up
to 12,5 % at −50 V. The standard deviation of the pulse width over all generators for pulse 1 for three
levels −50 V, −100 V and −150 V varies between 5,4 % and 6,1 % for open load conditions. The maximal
deviation increases up to 15 % at −50 V. All generators are well within the standardized tolerances
(required for −100 V).
The standard deviation of the pulse voltage over all generators for pulse 1 for three levels −50 V, −100 V
and −150 V varies between 3,3 % and 4,4 % for 10Ω conditions. The maximal deviation increases up to
7,5 % at −150 V. The standard deviation of the pulse width over all evaluated generators for pulse 1 for
three levels −50 V, −100 V and −150 V varies between 3,9 % and 5 % for 10Ω conditions. The maximal
deviation increases up to −13,3 % at –100 V. One generator failed the pulse width requirements with
−46,7 % and has been excluded from deviation assessment. All generators except one (excluded) are
within the standardized tolerances (required for −100 V).
More information about the evaluated pulse parameters and monitored pulse wave forms are given in
Annex A.
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ISO/TR 7637-5:2016(E)

For compliance verification of pulse 2a, the maximal pulse voltage and the pulse width at four different
test levels were measured. Furthermore, the deviation to the standardized values was evaluated.
Table 4 shows the verification results.
Table 4 — Generator verification result summary pulse 2a
Pulse voltage U deviation % Pulse width t deviation %
s d
Generator
Supply
voltage
Test-pulse Load U standard t standard
s d
U
a
U
s
(min/max) (min/max) (min/max) (min/max)
ISO 2a
open-load no open 75 V 75 V ± 7,5 V ±10 % 50 µs ± 10 µs ±20 %
a
definition
3,0 % 6,9 %
result no open 50 V 48 V/51 V 45 µs/58 µs
(−4,0%/+5,6%) (−10,0 %/15,2 %)
2,9 % 6,6 %
a
result no open 75 V 72 V/78 V 45 µs/55 µs
(−3,5 %/+3,9 %) (−10,0 %/10%)
1,6 % 7,1 %
result no open 100 V 97 V/101 V 45 µs/55 µs
(−2,9 %/+1,8 %) (−10,0 %/10 %)
1,6 % 8,3 %
result no open 125 V 120 V/126 V 44 µs/56 µs
(−3,6 %/1,4 %) (−12 %/12 %)
ISO 2a
2-Ω-load no 2Ω 75 V 37,5 V ±7,5 V ±20 % 12 µs ± 2,4 µs ±20 %
a
definition
9,4 % 10,6 %
result no 2Ω 50 V 19 V/26 V 11,8 µs/15 µs
(−24,8 %/+4,0 %) (−1,7 %/25 %)
8,3 % 8,6 %
a
result no 2Ω 75 V 33 V/41 V 11,8 µs/14,4 µs
(−13 %/+9,2 %) (−1,7 %/20 %)
7,0 % 7,3 %
result no 2Ω 100 V 44 V/53 V 11,8 µs/14 µs
(−11,3 %/+5,8 %) (−1,7 %/16,7 %)
7,7 % 6,4 %
result no 2Ω 125 V 56 V/68 V 11,8 µs/13,7 µs
(−10,9 %/+8 %) (−1,7 %/14,2 %)
a
Values to be verified according to ISO 7637-2 definition.
The standard deviation of the pulse voltage over all generators for pulse 2a for four levels 50 V, 75 V,
100 V and 125 V varies between 1,6 % and 3 % for open load conditions. The maximal deviation
increases up to 5,6 % at 50 V. The standard deviation of the pulse width over all generators for pulse
2a for four levels 50 V, 75 V, 100 V and 125 V varies between 6,6 % and 8,3 % for open load conditions.
The maximal deviation increases up to 15,2 % at 50 V. All generators are well within the standardized
tolerances (required for 75 V).
The standard deviation of the pulse voltage over all generators for pulse 2a for four levels 50 V, 75 V,
100 V and 125 V varies between 7 % and 9,4 % for 2Ω load conditions. The maximal deviation increases
significantly up to 24,8 % at 50 V. The standard deviation of the pulse width over all evaluated
generators for pulse 2a for four levels 50 V, 75 V, 100 V and 125 V varies between 6,4 % and 10,6 % for
2Ω load conditions. The maximal deviation increases significantly up to 25 % at 50 V. One generator
failed the pulse width requirements with +38,3 % and has been excluded from deviation assessment.
All generators except one (excluded) are within the standardized tolerances (required for 75 V).
More information about the evaluated pulse parameters and monitored pulse wave forms are given in
Annex A.
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ISO/TR 7637-5:2016(E)

4.3.3 Verification results with extended setup definitions
For verification of the different generator performance for pulse 1 under test conditions with application
load impedances the same tests have been performed. The maximal pulse voltage and the pulse width
at three different test levels were measured and the deviations to the expected pulse voltage values
were evaluated. Two different loads, low resistive load 1Ω and high impedance load 1kΩ//100nF, were
used. Table 5 shows the verification results.
Table 5 — Generator extended verification result summary for pulse 1
Pulse tar-
Pulse voltage
Generator U deviation %
s
get voltage
Supply
voltage standard
Test-pulse Load U
s
U
s
U
a
U (min/max)
s
(min/max)
(min/max)
ISO 1
open-load no open −100 V −100 V −100 V ± 10 V ±10 %
definition
ISO 1
10-Ω-load no 10Ω −100 V −50 V −50 V ± 10 V ±20 %
definition
9,1 %
result no 1Ω −50 V −4,6 V −5,6 V/−4,2 V
(−7,7 % /+24,4 %)
8,1 %
result no 1Ω −100 V −9,1 V −10,6 V/−8,3 V
(−8,6 %/+16,8 %)
23,2 %
result no 1Ω −150 V −13,6 V −25 V/−12,4 V
(−9,0 %/+83,1 %)
7,5 %
result no 1kΩ||100nF −50 V −49,5 V −61 V/−45 V
(−9,6 %/+23,4 %)
10,4 %
result no 1kΩ||100nF −100 V −99 V −133 V/−92 V
(−6,8 %/+34,8 %)
12,1 %
result no 1kΩ||100nF −150 V −148 V −204 V/−140 V
(−5,9 %/37,4 %)
The standard deviation of the pulse voltage over all generators for pulse 1 for three levels −50 V,
−100 V and −150 V varies between 8,1 % and 23,2 % for 1Ω load conditions. But the maximal deviation
increases significantly up to 83 % at −150 V.
The standard deviation of the pulse voltage over all generators for pulse 1 for three levels −50 V, −100 V
and −150 V varies between 7,5 % and 12,1 % for 1kΩ||100nF load conditions. The maximum deviation
is 37,4 % at −150 V.
Although all generators are well within the standardized tolerances under test conditions with
application load impedances, the results are spread over a wide range up to 83 % deviation which needs
to be solved.
More information about the evaluated pulse parameters and monitored pulse wave forms are given in
Annex A.
For verification of the different generator performance for pulse 2a under test conditions with power
supply and connected application load impedances the same tests have been performed. The maximal
pulse voltage and the pulse width at four different test levels were measured and the deviation to the
expected pulse voltage values was evaluated. Four different loads were used (open, match, low resistive
load 1Ω and high impedance load 1kΩ//100nF). Table 6 shows the verification results.
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Table 6 — Generator extended verification result summary for pulse 2a
Gen-
Pulse voltage
Pulse tar- U deviation % Supply U Pulse U
s a s
Supply erator
get voltage standard under swing overshoot
Test-pulse Load U
s
voltage
U
a
(min/max) (min/max) (min/max) (min/max)
(min/max)
U
s
ISO 2a
open-load
no open 75 V 75 V±7,5 V ±10 % — —
definition
ISO 2a
2-Ω-load
no 2Ω 75 V 37,5 V±7,5V ±20 % — —
definition
3,1 %
result 13,5 V open 50 V 63,5 V 59 V/67 V — —
(−7,8 %/5,2 %)
3,4 %
result 13,5 V open 75 V 88,5 V 84 V/92 V — —
(−5,2 %/4,0 %)
6,1 %
result 13,5 V open 100 V 113,5 V 105 V/133 V — —
(−7,3 %/17,0 %)
2,6 %
result 13,5 V open 125 V 138,5 V 128 V/142 V — —
(−7,3 %/2,2 %)
8,0 %
result 13,5 V 2Ω 50 V 31,75 V 25 V/31 V −0,1 V/−6,5 V —
(−27,7 %/−2,6 %)
8,3 %
result 13,5 V 2Ω 75 V 44,25 V 30 V/43 V −0,2 V/−7,6 V —
(−31,3 %/−2,9 %)
8,6 %
−0,2 V/-
result 13,5 V 2Ω 100 V 56,75 V 39 V/56 V —
8,3 V
(−31,6 %/−5,1 %)
11,2 %
result 13,5 V 2Ω 125 V 69,25 V 48V/67 V −0,1 V/-8,6 V —
(−44,0 %/−4,4 %)
13,1 %
result 13,5 V 1Ω 50 V 21,17 V 15 V/23 V −0,1 V/-5 V —
(−29,1 %/+10,9 %)
9,1 %
result 13,5 V 1Ω 75 V 29,50 V 22 V/30 V −0,3 V/-7,8V —
(−25,9 %/1,5 %)
9,3 %
result 13,5 V 1Ω 100 V 37,83 V 28 V/40 V −0,4 V/-9,6V —
(−25,0 %/6,8 %)
12,5 %
−0,4 V/-
result 13,5 V 1Ω 125 V 46,17 V 35 V/47 V —
10,3V
(−45,3 %/2,2 %)
1kΩ|| 13,3 %
result 13,5 V 50 V 63,40 V 60 V/93 V — −5,5 %/47 %
100nF (−5,5 %/+47 %)
1kΩ|| 12,4 %
result 13,5 V 75 V 88,35 V 101 V/142 V — 14,8 %/61 %
100nF (14,8 %/61 %)
1kΩ|| 18,1 %
result 13,5 V 100 V 113,30 V 114 V/201 V — 0,9 %/77 %
100nF (0,9 %/77 %)
1kΩ|| 17,0 %
result 13,5 V 125 V 138,25 V 167 V/260 V — 20,7 %/88 %
100nF (20,7 %/+88 %)
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ISO/TR 7637-5:2016(E)

The results in the Table 6 show that as soon as the generators are connected to the battery supply
(13,5 V) and loaded, a significant spread of the 2a pulse parameters can be observed depending on the
generator type.
For supplied and 2Ω loaded generators, the pulse voltage starts to deviate from the expected level in a
range between −2,9 % and −31,3 % for 75 V pulse voltage, for example.
The standard deviation of the pulse voltage over all generators for pulse 2a for four levels 50 V, 75 V,
100 V and 125 V varies between 9,1 % and 13,1 % for 1Ω load conditions. But the maximal deviation
increases significantly up to −45,3 % at 125 V.
The standard deviation of the pulse voltage over all generators for pulse 2a for four levels 50 V, 75 V,
100 V and 125 V varies between 12,4 % and 18,1 % for 1kΩ||100nF load conditions. The maximum
deviation is 88 %.
Additionally, for 75 V generator level, an under swing in the supply voltage occurs depending on the
generator type between −0,2 V and −7,6 V for 2Ω load. Higher load currents of the DUT and higher pulse
voltages lead to a deeper under swing, for example, −10,3 V for 125 V pulse at a 1Ω load.
For high impedance loads (e.g. sensor devices) represented by a 100nF capacitor in parallel to a 1kΩ
resistor, a generator dependent over shoot of the pulse voltage was observed.
For the 75 V pulse voltage, the overshoot is in the range of 14,8 % up to 61 %. For higher pulse voltages,
the overshoot voltage and range increase. For 125 V pulse voltage, for example, an overshoot between
20,7 % and 88 % was observed which nearly doubles the pulse voltage.
Although all generators are well within the standard specification, different generator types lead to a
wide range of test results far-off the expected tolerances when loaded with a more realistic test and
load conditions.
4.4 Verification summary — Missing generator definitions leading to different results
Existing pulse generators are defined by a verification procedure limited to source impedance and
open load voltage. The evaluation with a loaded generator is used to determine the internal source
impedance and to check the pulse energy capability of the generator. The tolerances are relatively wide,
which may also lead to generator-dependent test results.
Beyond that, secondary
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