EMC / ESD Pulse Measurements Using Oscilloscopes September /16/$ IEEE

EMC / ESD Pulse Measurements Using 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

Quadrants of EMC/ESD Testing Radiated Emissions Will the EUT create emissions that interfere with the operation of other products? Radiated Immunity Will the EUT be susceptible to emissions from other devices, either through the air or via cables? EUT = Equipment Under Test Conducted Emissions How much noise voltage is injected back into the mains by the EUT? Conducted Immunity Will the EUT be susceptible to transients generated by switching of capacitive or inductive components? Oscilloscopes are used for: Radiated Immunity Conducted Immunity Conducted Immunity Pulsed EMI tests include: ESD (Electrostatic Discharge) EFT (Electrical Fast Transient) Surge Testing

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)

Diagram of ESD calibration using scope

ESD Testing Electrostatic Discharge Measurement Steps Typical Pulse Characteristics T rise = 0.7 to 1.0 ns T fall = 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 Definitions How 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 Top Clock pulses with clearly delineated Top and Base Two main modes emerge from the voltage level histogram, identifying the steady state values of Top and Base Base

Top and Base are not meaningful for ESD pulse measurements What happens when standard pulse parameters are applied to an ESD waveform? Top ESD pulse 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. 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 Top Base

ESD Pulse Rise Time Definitions Require 0% and Max 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.

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 Max 0% Risetime is correctly calculated as 854 picoseconds on this ESD pulse

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

Verification Of The Output Characteristics Of The Test Pulse Generator current shunt target 20 db attenuator connects to current shunt target output double shielded cable leads to 6 db attenuators on input of scope Teledyne LeCroy in cooperation with Hitachi Automotive Systems

Verification Of The Output Characteristics Of The Test Pulse Generator Teledyne LeCroy in cooperation with Hitachi Automotive Systems

Using 0% - Max Thresholds for ESD Rise Time Measurement Teledyne LeCroy in cooperation with Hitachi Automotive Systems

Calculating ESD Pulse Maximum (first peak current) Teledyne LeCroy in cooperation with Hitachi Automotive Systems

Voltage level calculation at 400 ns delay after 50% incident pulse level (current at t 1 ) Teledyne LeCroy in cooperation with Hitachi Automotive Systems

Voltage level calculation at 800 ns delay after 50% incident pulse level (current at t 2 ) Teledyne LeCroy in cooperation with Hitachi Automotive Systems

ESD pulse parameters of rise time, first peak current, and currents at t 1 and t 2 First peak current Rise time Current at t 1 Current at t 2 Teledyne LeCroy in cooperation with Hitachi Automotive Systems

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 Approximately 50 sample points on rising edge ESD pulse sampled at 4 GS/s Approximately 5-6 sample points on rising edge ESD pulse sampled at 2 GS/s Not enough sample points to correctly characterize rising edge ESD pulse sampled at 1 GS/s 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 Measured rise time: 839 ps ESD pulse sampled at 4 GS/s Measured rise time: 865 ps (3% measurement error) ESD pulse sampled at 2 GS/s Measured rise time: 1.070 ns ESD pulse sampled at 1 GS/s Measured rise time < 1.54 ns, and measurement warning is reported

Sample Rate Goal for ESD Pulses: Rule Of Thumb: Acquire At Least 10 Sample Points On The Rising Edge 50 sample pts on rising edge 10 sample pts on rising edge Measured risetime result is within one half of one percent (measurement result is within 0.5% of 839 ps)

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 Measurements This 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) available at full scale

Dynamic Range and Signal Integrity For ESD Pulse Measurements This Concept Holds True for All Digitizing Real Time Scopes 7 vertical bits (128 ADC levels) available at full scale or 11 vertical bits (2048 ADC levels) available at full scale

Dynamic Range and Signal Integrity For ESD Pulse Measurements This Concept Holds True for All Digitizing Real Time Scopes 6 vertical bits (64 ADC levels) available at full scale or 10 vertical bits (1024 ADC levels) available at full scale

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 T rise = typically 1.2 to 10 ms T fall = 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 Teledyne LeCroy in cooperation with Hitachi Automotive Systems

Surge Verification Measurements Including Rise Time, Pulse Width, Maximum, Area, and Charge Teledyne LeCroy in cooperation with Hitachi Automotive Systems

Application example: The ISO10605:2008 standard requires the measurement of 10 consecutive parameter values

ISO10605:2008 pulse measurement statistics of 10 consecutive acquisitions Teledyne LeCroy in cooperation with Hitachi Automotive Systems

Histogram statistical distribution of 10 consecutive acquisitions Teledyne LeCroy in cooperation with Hitachi Automotive Systems

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 Teledyne LeCroy in cooperation with Hitachi Automotive Systems

Method 1 to characterize voltage level: Runt Trigger on individual pulses Teledyne LeCroy in cooperation with Hitachi Automotive Systems

Method 2 to characterize voltage level: Gated Mean Measurement Teledyne LeCroy in cooperation with Hitachi Automotive Systems

Dropout and Interrupt Testing Method 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 Pulse Characteristics 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 Transient Measurement Steps Pulse Characteristics T rise = 5ns T fall = 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 Transient Measurement 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 Event occupies 1% of acquisition time Empty space Empty space 100 ns/div

Maximizing Acquisition Memory for Events Acquisition time optimized for event 1 ns/div

Maximizing Acquisition Memory for Events Mosaic of events is acquired while optimizing acquisition memory, and displayed without empty spaces between events

Maximizing Acquisition Memory for Events 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.

EFT Testing Electrical Fast Transient Sequence Mode and Octal Grid Sequenced acquisition of 5 EFT bursts Zoom of EFT pulses Zoom of one EFT burst Zoom of EFT pulses Zoom of one EFT pulse Zoom of one EFT pulse Zoom of one EFT pulse FFT

Individual EFT Pulses Teledyne LeCroy in cooperation with Hitachi Automotive Systems

One EFT Burst - Acquired at 2.5 GS/s - note linear top of burst Teledyne LeCroy in cooperation with Hitachi Automotive Systems

One EFT Burst - Acquired at 125 MS/s - note amplitude distortion at top of burst Teledyne LeCroy in cooperation with Hitachi Automotive Systems

Comparison of one EFT burst captured at 1.25 GS/s and 125 MS/s 125 MS/s 2.5 GS/s Teledyne LeCroy in cooperation with Hitachi Automotive Systems

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 Teledyne LeCroy in cooperation with Hitachi Automotive Systems

Frequency measurement parameter measures only values in the range between 9kHz and 11kHz Teledyne LeCroy in cooperation with Hitachi Automotive Systems

Negative width parameter calculates gap time with values in range Teledyne LeCroy in cooperation with Hitachi Automotive Systems

EFT Rise Time With 0-Max Thresholds Teledyne LeCroy in cooperation with Hitachi Automotive Systems

Note the difference between P2 Width (gap time) and P4 Width (EFT pulse width) Teledyne LeCroy in cooperation with Hitachi Automotive Systems

EFT Max, Area, and Energy Calculations Teledyne LeCroy in cooperation with Hitachi Automotive Systems

Electrical Fast Transient (EFT) Debugging Techniques Using Segmented Memory

20 EFT Bursts Captured Using Segmented Memory Teledyne LeCroy in cooperation with Hitachi Automotive Systems

Inter-burst EFT Timestamps Teledyne LeCroy in cooperation with Hitachi Automotive Systems

Inter-pulse EFT Timestamps: Individual EFT pulses in segmented memory Teledyne LeCroy in cooperation with Hitachi Automotive Systems

Overlay And Waterfall Of EFT Pulses Verifies Correct EFT Pulse Shape Characteristics Teledyne LeCroy in cooperation with Hitachi Automotive Systems

Segmented Overlay And Waterfall Of EFT Pulses Highlights Anomalies Reveals Possible Bad Contact Within The Transient Simulator Teledyne LeCroy in cooperation with Hitachi Automotive Systems

MIL-STD-461G Department 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 nonsafety 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 Evaluation Deviation detection of a device under test (DUT) during exposure to a disturbance Functional state of the DUT is output through non-conductive fiber optic cables Mechanical mode tuner Devices under test are exposed to electric fields high enough to effect operation of nonshielded equipment. Transmit and receive antennas generate a controlled electric field RF-hardened fiber optic transmitters Teledyne LeCroy in cooperation with Hitachi Automotive Systems

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 Teledyne LeCroy in cooperation with Hitachi Automotive Systems

Views from inside and outside of the reverberant chamber Teledyne LeCroy in cooperation with Hitachi Automotive Systems

Simulated ECU (Electronic Control Unit) outputs: Two PWM outputs, a driver actuator signal, and a CAN split signal Teledyne LeCroy in cooperation with Hitachi Automotive Systems

Mask testing ECU outputs: example with passing results Teledyne LeCroy in cooperation with Hitachi Automotive Systems

Mask testing ECU outputs exceeding the tolerance mask criteria Teledyne LeCroy in cooperation with Hitachi Automotive Systems

Special Thanks To: Special thanks to Hitachi Automotive Systems (an ISO accredited lab) for providing access to EMC test setups, equipment, expertise and insight. Teledyne LeCroy in cooperation with Hitachi Automotive Systems

Questions?