emc / esd pulse measurementsdiagram of esd calibration using scope esd testing –electrostatic...

EMC / ESD Pulse MeasurementsUsing Oscilloscopes – September 2016

978-1-5090-1416-3/16/$31.00 ©2016 IEEE

Contents

• EMC Measurement Categories and Requirements

• ESD Pulse Test Requirements and Measurement Thresholds

• Sequenced Acquisition for EFT (Electrical Fast Transient) Debug

• Surge Testing

• MIL-STD-461G

• Voltage Testing Below Battery Level

• Sample Rate and V/div Effect on ESD Pulse Measurements

• Level-At-Pulse, Time-To-Value, and Parameter Limiters

• ESD RC Time Constant Measurement

• Radiated Immunity Testing

Radiated

EmissionsWill the EUT create

emissions that interfere

with the operation of

other products?

Conducted

EmissionsHow much noise

voltage is injected back

into the mains by the

EUT?

Radiated

ImmunityWill the EUT be

susceptible to emissions

from other devices,

either through the air or

via cables?

Conducted

ImmunityWill the EUT be

susceptible to transients

generated by switching

of capacitive or

inductive components?

Quadrants of EMC/ESD Testing

Oscilloscopes are used for: Radiated Immunity

Conducted Immunity

Conducted Immunity Pulsed EMI tests include: ESD (Electrostatic Discharge)

EFT (Electrical Fast Transient)

Surge Testing

EUT = Equipment Under Test

ESD Pulse Test

Requirements

Conducted Immunity General Test Requirements

Generate a Burst, Surge, or ESD pulse

Verify the pulse shape from the generator using an oscilloscope, verifying parameters such as:

Rise Time

Fall Time

Pulse Width

Frequency

Pulse Repetition interval

Burst Repetition interval

Ensure that the DUT still operates correctly during test, for example:

Automotive engine control unit still transmits proper messages

Telecom board serial data messages are uncorrupted

Consumer electronics item still functions

ESD Standards examples:

IEC 61000-4, EN 61000-4, ITU, UL, FCC, Telcordia, ANSI, Bellcore, ISO10605:2001, ISO10605:2008, MIL-STD-461G, proprietary military, proprietary automotive, etc.

The majority of Immunity Testing follows the IEC 61000 (CE Mark)

http://en.wikipedia.org/wiki/Image:Cemark.svg

http://en.wikipedia.org/wiki/Image:Cemark.svg

Diagram of ESD calibration using scope

ESD Testing – Electrostatic DischargeMeasurement Steps

Typical Pulse Characteristics

Trise = 0.7 to 1.0 ns

Tfall = 0.7 to 1.0 ns

Measurement Needs

Capture a Single Pulse

Measure one pulse, verify rise time

for positive pulses, verify fall time for

negative pulses

1 GHz, 2 GHz, or 4 GHz+ scope

depending on standard specification

How is risetime measured on this ESD pulse?

10%-90% risetime measurement first requires the

determination of 0% and 100% levels.

Pulse Measurement Definitions

IEEE Standard Pulse DefinitionsHow Oscilloscopes Measure Pulse Parameters

Oscilloscopes determine pulse parameters from Top and Base values

IEEE Pulse Definitions How Pulse Measurements Are Determined

Pulse measurement definitions are defined by the

IEEE Std 181-2003 "IEEE standard on

transitions, pulses, and related waveforms"

Oscilloscopes conform to the IEEE pulse

measurement definitions, and Top and Base are

determined statistically based on the two modes

of a voltage level histogram.

Top and Base form the 100% and 0% reference

levels which are used for measurements such as

amplitude, risetime, falltime, period, frequency,

width, duty cycle, overshoot, and virtually every

timing measurement.

Top and Base must first be calculated correctly in

order for timing and amplitude measurements to

produce the correct measurement result.

Clock Top and Base are correctly determined from a voltage histogram

Clock pulses with clearly

delineated Top and Base

Top

Base

Two main

modes emerge

from the voltage

level histogram,

identifying the

steady state

values of Top

and Base

Top and Base are not meaningful for ESD pulse measurements

ESD pulse

What happens when

standard pulse parameters

are applied to an ESD

waveform?

A voltage level histogram of this ESD pulse

does not result in the identification of two

main modes. Standard pulse parameters

will not yield correct results in this case.

Top

Base

ESD Top and Base are not meaningful for pulse measurements

With Top (100%) and Base (0%) identified in the

following locations, the 10%-90% risetime

measurement will only encompass a very small portion

of the total ESD pulse rising edge

Base

Top

Different than IEEE pulse definitions, EMC pulse

definitions (for example the IEC 61000-4-2 standard)

use 0% and Max, instead of Top and Base to calculate

10%-90% risetime

An oscilloscope must use 0% and Max thresholds in

order to perform the EMC-specific measurement

EMC pulse measurements now require the use of

thresholds set to 0% and Max (where Max is the peak

voltage level of the waveform), instead of Top and

Base, to meet the measurement specification. Modern

oscilloscopes have begun to allow for EMC pulse

parameter measurements using threshold settings of

peak-to-peak, 0% to Max, and 0% to Min along with

the standard absolute or percent levels.

ESD Pulse Rise Time Definitions Require 0% and Max

Risetime calculated using standard IEEE pulse parameter definitions

Risetime is incorrectly calculated as 494 picoseconds on this ESD

pulse. Note the risetime detailed marker location.

Risetime calculated using EMC thresholds

Risetime is correctly calculated as 854

picoseconds on this ESD pulse

Max

0%

Effect of thresholds on the Width

measurement of this ESD pulse

Standard and EMC thresholds for ESD pulse width

The pulse width and risetime are measured, both with and without EMC

thresholds applied. In parameter 1 (P1), the thresholds are set to 0% - Max, and

the pulse width is measured correctly as 2.109 nanoseconds. In parameter 2

(P2), the thresholds are set to the standard scope threshold of 50% of Top and

Base. In this case, the measurement is incorrectly reported as 50.348

nanoseconds -- an error of 2287%. The width measurement was impacted so

significantly, that the 50% threshold between Top and Base actually produced a

width measurement on the wrong pulse shape. Parameter 3 (P3) is set to the

correct EMC threshold of 0% to Max, producing a correct electrostatic pulse

risetime measurement of 833 picoseconds. Notice that in parameter 4 (P4), the

standard risetime is incorrectly reported as 873 picoseconds. When using

standard pulse parameter measurements, erroneous values can be obtained.

Use of standard pulse thresholds produced a

2287% measurement error on this ESD pulse. Note

the threshold indicated in the width@level

parameter marker for each.

EMC Level-At-Pulse,

Time-To-Value,

Parameter Limiting

EMC Level-At-Pulse Parameter

EMC Time-To-Half Value Parameter

Parameter limiting technique for ESD width measurement

Because EMC pulses often have pulse perturbations on the falling edge of the pulse, these

can result in false measurement readings when using standard parameters. For example,

if the falling edge had ringing oscillations which repeatedly crossed the threshold, then

multiple false width readings would be possible. For this reason, a measurement filtering

capability which can limit the number of pulses the scope measures in an acquisition is

needed. This measurement filtering capability, now available on modern scopes, allows for

pulse-like perturbations on the falling edge of a pulse to be ignored and excluded from the

measurement results. Parameter statistics could be accumulated on the first pulse in

conjunction with parameter limiting subsequent perturbations.

A Parameter Limiter Is Needed To Avoid Measuring The Bounce Areas As Widths

Parameter Limiter Isolates Correct Width

ESD Verification

Test Setup Example

current shunt

target

• 20 dB attenuator connects to

current shunt target output

• double shielded cable leads to

6 dB attenuators on input of

scope

Verification Of The Output Characteristics Of The Test Pulse Generator

Teledyne LeCroy in cooperation with Hitachi Automotive Systems

Verification Of The Output Characteristics Of The Test Pulse Generator


Using 0% - Max Thresholds for ESD Rise Time Measurement


Calculating ESD Pulse Maximum (first peak current)


Voltage level calculation at 400 ns delay after 50% incident pulse level (current at t1)


Voltage level calculation at 800 ns delay after 50% incident pulse level(current at t2)


ESD pulse parameters of rise time, first peak current, and currents at t1 and t2


Rise time

First peak current

Current at t1 Current at t2

Sample Rate's Impact On Rise Time

For ESD Pulse Measurements

Effect of Sample Rate On ESD Rise Time Measurements

ESD pulse sampled

at 40 GS/s

ESD pulse sampled

at 4 GS/s

ESD pulse sampled

at 2 GS/s

ESD pulse sampled

at 1 GS/s

Approximately 50 sample

points on rising edge

Approximately 5 - 6 sample

points on rising edge

Not enough sample

points to correctly

characterize rising edge

Not enough sample

points to correctly

characterize rising edge

Effect of Sample Rate On ESD Rise Time Measurements

ESD pulse sampled

at 40 GS/s

ESD pulse sampled

at 4 GS/s

ESD pulse sampled

at 2 GS/s

ESD pulse sampled

at 1 GS/s

Measured rise time:

839 ps

Measured rise time:

865 ps

Measured rise time:

1.070 ns

Measured rise time < 1.54 ns,

and measurement warning is

reported

(3% measurement error)

Sample Rate Goal for ESD Pulses:

Rule Of Thumb: Acquire At Least 10 Sample Points On The Rising Edge

Measured risetime

result is within one

half of one percent

(measurement result is

within 0.5% of 839 ps)

50 sample pts on

rising edge

10 sample pts on

rising edge

Measurement Method Background:Sparse Math Operator Was Used To Isolate Sample Rate Effect On Same Input Waveform

Dynamic Range and Signal Integrity

For ESD Pulse Measurements

Dynamic Range and Signal Integrity For ESD Pulse MeasurementsThis Concept Holds True for All Digitizing Real Time Scopes

8 vertical bits (256 ADC levels)

available at full scale

or 12 vertical bits (4096 ADC levels)


Scope Block Diagram Shows Why Maximizing Waveforms In Grid Maximizes Measurement Accuracy This Concept Holds True for All Digitizing Real Time Scopes

Surge Testing

Surge Testing General Test Requirements

Pulse Characteristics

Trise = typically 1.2 to 10 ms

Tfall = typically 20 to 10,000ms

Measurement Needs

Rise time

Pulse Width

Maximum

Area

Charge

A Surge pulse also does not have a clearly-defined Top and Base

The pulse characteristics of a surge pulse also do not conform to the

IEEE pulse parameter definitions, because the surge does not have high

and low steady-state values. After a fast linear rise to a sharp peak, the

waveform then exponentially decays toward, but does not quickly reach,

an asymptote. With no steady-state values, the surge will produce

indeterminate Top and Base values. Because Top and Base must be

determined in order to calculate the thresholds used for risetime,

falltime, and pulse width, the measurements therefore become invalid

when using traditional oscilloscope clock pulse parameters.

Hardware Configuration for Surge Verification


Surge Verification Measurements Including Rise Time, Pulse Width, Maximum, Area, and Charge


Application example:The ISO10605:2008 standard requires

the measurement of 10 consecutive parameter values

ISO10605:2008 pulse measurement statistics of 10 consecutive acquisitions


Histogram statistical distribution of 10 consecutive acquisitions


Application example:The ISO10605:2001(E) standard (pg 13) requires the

measurement of the RC time constant value of the

decay of an air discharge ESD pulse.

A location is referenced at a stable point on the waveform,

then a second point is located at 37% voltage level of the

first value. The time difference between the two points

is calculated to determine the RC time constant

of the decay time.

Hardware setup for RC time constant measurement

Published: 978-1-5090-1416-3/16/$31.00 ©2016 IEEE

ISO10605:2001(E) RC time constant measurement

Published: 978-1-5090-1416-3/16/$31.00 ©2016 IEEE

ISO10605:2001(E) RC time constant measurement script

Published: 978-1-5090-1416-3/16/$31.00 ©2016 IEEE

Script used to measure the RC Time Constant

Set app = CreateObject("LeCroy.XStreamDSO") ' ActiveX COM handle

numSamples = InResult1.Samples ' number of sample points in acquisition

scaledData = InResult1.DataArray(True) ' waveform sample points array

If (app.Measure.P1.Source1) <> "F4" Then ' if the source for P1 isn't F4

app.Measure.P1.Source1 = "F4" ' then set it to F4

app.Measure.P1.Source2 = "None" ' and set the other input to be blank

End If ' Force F4 to be the input source for this script at all times

trigpt = app.Math.F4.Out.Result.HorizontalOffset ' Determine the trigger point / horizontal offset

sampleres = app.Math.F4.Out.Result.HorizontalPerStep ' Determine the spacing between sample points

horzunits = app.Math.F4.Out.Result.HorizontalUnits ' Query for units (e.g. Seconds, etc.)

vertunits = app.Math.F4.Out.Result.VerticalUnits ' Query for units (e.g. Volts, etc.)

x2_array_position = numSamples - 35000 ' hardcoded value for X2 that placed it on the rightmost graticule on the screen

x2_time_position = trigpt + (sampleres * x2_array_position) ' calculate the rightmost falling edge value in terms of time (rather than an array index)

e_constant = 0.367879441 ‘value from ISO spec

i = x2_array_position ' counter position

x1_target_value = scaledData(x2_array_position)/(e_constant)

Do While (scaledData(i) < x1_target_value) And (i > 1)

i = i - 1

Loop

x1_array_position = i

x1_time_position = trigpt + (sampleres * x1_array_position)

x1_vertical_position = scaledData(x1_array_position)

x2_vertical_position = scaledData(x2_array_position)

labelsposition = Cstr(x1_time_position) & "," & Cstr(x2_time_position)

app.Math.F4.ViewLabels = True ' turn label display on

app.Math.F4.LabelsPosition = labelsposition ' set position of labels

app.Math.F4.LabelsText = "X1" & "," & "X2" ' set text of labels

OutResult.VerticalResolution = 0.000000001 ' set fine resolution of measurement output (for example, picosecond timing resolution)

OutResult.VerticalUnits = "S" ' set horizontal units of measurement to be the same as the horizontal units of the input waveform (e.g. seconds)

OutResult.Value = x2_time_position - x1_time_position ' time constant is reported

app.Measure.P2.Operator.Value = (x2_vertical_position / x1_vertical_position)

app.measure.p1.alias="RC Time Constant"

app.measure.p2.alias="Y1/Y2 ratio"

app.measure.p3.alias="Y1/Y2 percent"

Published: 978-1-5090-1416-3/16/$31.00 ©2016 IEEE

Y1/Y2 ratio is computed with a “pushed” parameter constant value

Published: 978-1-5090-1416-3/16/$31.00 ©2016 IEEE

Convert Y1/Y2 to Ratio in Percent

Published: 978-1-5090-1416-3/16/$31.00 ©2016 IEEE

ISO10605:2001(E) RC time constant on inverted pulse

Published: 978-1-5090-1416-3/16/$31.00 ©2016 IEEE

Trend Plot Shows Data Log of RC Time Constant Values

Published: 978-1-5090-1416-3/16/$31.00 ©2016 IEEE

Application example:Voltages Referenced Below Battery Level

Battery Voltage Signal From Generator


Method 1 to characterize voltage level: Runt Trigger on individual pulses



Method 2 to characterize voltage level: Gated Mean Measurement

Dropout and Interrupt TestingMethod 1 Runt / Glitch Triggering Can Also Be Used To Capture Dropouts and Interrupts

Monitor AC or DC voltage

line with oscilloscope during

EMC testing

Verify that dropout or

interrupt occurred, and that

device under test was

unaffected

Electrical Fast Transient (EFT)

Testing

Transient Testing


Capacitive load dump

Inductive kickback/spike (back EMF from motor turn off)

Measurement Needs

Capture Time – longer the better:

Relay bounce (ms to ms)

Transient time

ms (motor)

ns (FET switch)

Measure 50-100 MHz transient

10s capture = 2Mpts at 100 MHz Sample Rate

EFT Testing – Electrical Fast TransientMeasurement Steps


Trise = 5ns

Tfall = 50ns

Burst of many 5x50 pulses

Measurement Needs

Capture 2ms of burst

Measure one pulse, verify shape (rise, fall,

width)

Measure burst frequency (10-100 kHz)

Measure Capture time of burst packet (2ms)

Measure burst packet rate (300ms)

EFT Testing – Electrical Fast TransientMeasurement Statistics

All-instance measurements characterizes all

76 rise times and pulse widths in this EFT

burst. EFT bursts can be batch processed to

determine EFT pulse characteristics, burst

frequency, and packet rate (shown next).

Maximizing Acquisition Memory for Events

100 ns/div

Empty space Empty space

Event occupies 1%

of acquisition time


Acquisition time

optimized for event

1 ns/div


Mosaic of events is acquired while optimizing

acquisition memory, and displayed without

empty spaces between events


Individual timestamps for each event listed with segment

acquisition time and intersegment time. This will

automatically measure the EFT burst packet rate.

Mosaic of events is acquired while optimizing

acquisition memory, and displayed without

empty spaces between events

EFT Testing – Electrical Fast TransientSequence Mode and Octal Grid

Sequenced acquisition

of 5 EFT bursts

FFT

Zoom of one

EFT pulse

Zoom of one

EFT pulse

Zoom of one

EFT pulse

Zoom of one

EFT burst

Zoom of EFT

pulses

Zoom of EFT

pulses

Individual EFT Pulses


One EFT Burst - Acquired at 2.5 GS/s - note linear top of burst



One EFT Burst - Acquired at 125 MS/s - note amplitude distortion at top of burst

Comparison of one EFT burst captured at 1.25 GS/s and 125 MS/s


125 MS/s 2.5 GS/s

Effect of Sample Rate on EFT Pulse Capture Sampled at 100 MS/s vs. 1.25 GS/s


100 MS/s 2.5 GS/s

Frequency measurement parameter measures only values in the range between 9kHz and 11kHz


Negative width parameter calculates gap time with values in range


EFT Rise Time With 0-Max Thresholds


Note the difference between P2 Width (gap time) and P4 Width (EFT pulse width)


EFT Max, Area, and Energy Calculations


Electrical Fast Transient (EFT)

Debugging Techniques

Using Segmented Memory

20 EFT Bursts Captured Using Segmented Memory


Inter-burst EFT Timestamps


Inter-pulse EFT Timestamps:Individual EFT pulses in segmented memory



Overlay And Waterfall Of EFT Pulses Verifies Correct EFT Pulse Shape Characteristics

Segmented Overlay And Waterfall Of EFT Pulses Highlights Anomalies Reveals Possible Bad Contact Within The Transient Simulator


MIL-STD-461GDepartment of Defense

Requirements for the Control of Electromagnetic Interference

Characteristics of Subsystems and Equipment

MIL-STD-461G

• CS117 and CS118 are new with the G version of

the standard specification

• Applicable to a wide variety of DoD systems

• CS117: Lightning strike testing

• CS118: ESD testing

“This requirement is applicable to all aircraft safety-critical equipment

interconnecting cables, including complete power cables, and

individual high side power leads. It is also applicable to non-safety

critical equipment with interconnecting cables/electrical interfaces that

are part of or connected to equipment performing safety critical

functions. It may be applicable to aircraft equipment performing non-

safety critical functions when specified by the procuring activity. This

requirement applies to surface ship equipment which is located above

deck or has interconnecting cables which are routed above deck.”

MIL-STD-461G CS116 damped sinusoid measurement

MIL-STD-461G EMC level-at-pulse and half life measurements

MIL-STD-461G multiple stroke and multiple burst lightning strike test

Surge Test example computing Rise Time, Pulse Width, Maximum, Area, and Charge

EMC - Radiated Immunity Testing

Radiated Immunity Testing - Real Time Functional Performance EvaluationDeviation detection of a device under test (DUT) during exposure to a disturbance

Devices under test

are exposed to

electric fields high

enough to effect

operation of non-

shielded equipment.

Transmit and receive

antennas generate a

controlled electric field


Functional state of the

DUT is output through

non-conductive fiber

optic cablesMechanical mode

tuner

RF-hardened fiber optic transmitters

Outside the reverberant chamber, oscilloscope masks test for acceptance criteria


Optical receiver

and O/E converter

16 channels performing mask test criteria such as

signal high level, signal low level, frequency, duty

cycle, and other criteria fit within tolerance limits

described in the test plan

Views from inside and outside of the reverberant chamber


Simulated ECU (Electronic Control Unit) outputs:Two PWM outputs, a driver actuator signal, and a CAN split signal


Mask testing ECU outputs: example with passing results


Mask testing ECU outputs exceeding the tolerance mask criteria


Special Thanks To:

Special thanks to Hitachi Automotive

Systems (an ISO accredited lab) for

providing access to EMC test setups,

equipment, expertise and insight.


Questions?

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