EMC FLEX BLOG A site dedicated to Automotive EMC Testing for Electronic Modules

Using DC Power Supply to simulate Automotive Battery for EMC testing

19. April 2021 08:23 by Christian in EMC/EMI, EMC TEST PLAN, Load Simulator
The DC Power Supply should be selected as follows:Rs (Internal Resistance) < 0.01 OHM DCZs (Inter

The DC Power Supply should be selected as follows:
Rs (Internal Resistance) < 0.01 OHM DC
Zs (Internal Impedance) = Rs for frequencies < 400 Hz.
Output Voltage:
▶ does not deviate more than 1 V from 0 to maximum load (including inrush current)
▶ recovers 63% of its maximum excursion within 100 ms
Vr (Superimposed Ripple Voltage):
▶ does not exceed 0.2 V peak-to-peak
▶ maximum frequency of 400 Hz

 When a battery is used for EMC testing, a charging source is needed to achieve the specified voltage reference levels.

It is important to ensure that the charging source does not affect the test.

 Linear Power Supplies are preferable vs Switching Power Supplies.

 Prior to CISPR 25 test methods ensure that the RF noise produced by the power supply is at least 6 dB lower than the limits specified in EMC Test Plan.

 If the Power Supply is located outside of the EMC test chamber, ensure thzt a bulkhead RF filter is used to prevent RF noise from entering or leaving the shielded enclosure.

 If using a HV battery, then it must be contained in a shielded enclosure.

 12V Power Supply Volatge = 13.5 (+0.5/-1.0)V

 24V Power Supply Voltage = 26 (+1.0/-2.0 V

CISPR25 Conduct Emissions Current Grounding Scheme

A few remarks on correct Load Simulator configuration for CISPR 25 Conducted Emissions Current test

A few remarks on correct Load Simulator configuration for CISPR 25 Conducted Emissions Current test method.

First of all you have to show the LISN in your EMC Test Plan block diagrams. The way the LS is connected is not identical for each CISPR 25 test method. I will never use a Load Simulator unless is no other way around or I would want to turn it into a RF filter box. Examples of CEI good and bad setups are shown below:




To clarify how a PWM maker is connected:

From EMC compliance perspective the goal is to avoid as much as possible common line impedances:


Christian Rosu



31. March 2021 07:12 by Administrator in
A/C = Air ConditioningA/F = Air/Fuel RatioA/T = Automatic Transmission or TransaxleABS = Antilock Br

A/C = Air Conditioning
A/F = Air/Fuel Ratio
A/T = Automatic Transmission or Transaxle
ABS = Antilock Braking System
ABSV = Air Bypass Solenoid Valve
AC = Alternating Current
ACTS = Air Charge Temperature Sensor
AFC = Air Flow Control
AFM = Air Flow Meter
AFS = Air Flow Sensor
ALCL = Assembly Line Communications Link
ALDL = Assembly Line Data Link
APS = Absolute Pressure Sensor
APS = Atmospheric Pressure Sensor
ASDM = Airbag System Diagnostic Module
ATDC = After Top Dead Centre
ATF = Automatic Transmission Fluid
ATS = Air Temperature Sensor
AWD = All Wheel Drive

B+ = Battery Positive Voltage
BARO = Barometric Pressure
BAT = Battery
BCM = Body Control Module
BHP = Brake Horse Power
BMAP = Barometric/Manifold Absolute Pressure Sensor
BPS = Back pressure Sensor
BPT = Back Pressure Transducer
BTDC = Before Top Dead Centre
Btu = British Thermal Units

C = Celsius
C3I = Computer Controlled Coil Ignition
CALPAK = Calibration Pack
CAN = Controller Area Network
CANP = Canister Purge Solenoid Valve
CAS = Crank Angle Sensor
CC = Cubic Centimetres
CDI = Capacitor Discharge Ignition
CEAB = Cold Engine Air Bleed
CECU = Central Electronic Control Unit
CER = Cold Enrichment Rod
CESS = Cold Engine Sensor Switch
CFI = Central Fuel Injection
CFI = Continuous Fuel Injection
cfm = Cubic Feet Per Minute
CID = cylinder identification sensor
CID = Cubic Inch Displacement
CIS = Continuous Injection System
CKP = Crankshaft Position Sensor
CMP = Camshaft Position Sensor
CO = Carbon Monoxide

CO2 = Carbon Dioxide

COP = Coil On Plug ignition

CPI = Central Port Injection

CPU = Central Processing Unit

CSSA = Cold Start Spark Advance

CSSH = Cold Start Spark Hold

CTS = Coolant Temperature Sensor

CTVS = Choke Thermal Vacuum Switch

CVR = Control Vacuum Regulator

dB = Decibels

DC = Direct Current

DEFI = Digital Electronic Fuel Injection

DFS = Deceleration Fuel Shutoff

DIS = Distributorless Ignition System

DIS = Direct Ignition System

DLC = Data Link Connector

DOHC = Double OverHead Camshaft

DTC = Diagnostic Trouble Code

DVOM = Digital Volt Ohm Meter

E2PROM = Electrically Erasable Programmable Read Only Memory

EACV = Electronic Air Control Valve

EBCM = Electronic Brake Control

Module EBM = Electronic Body Module

ECA = Electronic Control Assembly

ECM = Engine Control Module

ECT = Engine Coolant Temperature

ECU = Electronic Control Unit

EDIS = Electronic Distributorless Ignition System

EEPROM = Electronically Erasable Programmable Read Only Memory

E2PROM = Electronically Erasable Programmable Read Only Memory

EFC = Electronic Fuel Control

EFCA = Electronic Fuel Control Assembly

EFI = Electronic Fuel Injection

EGO = Exhaust Gas Oxygen Sensor

EGR = Exhaust Gas Recirculation

EGRPS = EGR Valve Position Sensor

EGRT = EGR Temperature

EI = Electronic Ignition

EMI = Electromagnetic Interference

EMR = Electronic Module Retard

EOS = Exhaust Oxygen Sensor

EOBD = European Onboard Diagnostics

EPOS = EGR Valve Position Sensor

EPROM = Erasable Programmable Read Only Memory (chip)

ESC = Electronic Spark Control

EST = Electronic Spark Timing

EVAP = Evaporative Emission System

EVP = EGR Valve Position Sensor

F = Fahrenheit

FBC = Feedback Carburettor System

FBCA = Feedback Carburettor Actuator

FCS = Fuel Control Solenoid

FDC = Fuel Deceleration Valve

FI = Fuel Injection

FLS = Fluid Level Sensor

ft.lb. = Foot Pound

FWD = Front-Wheel Drive

gal = Gallon

GDI = Gasoline Direct Injection

GEN = Generator

GND = Ground

GPM = Grams Per Mile

GVW = Gross Vehicle Weight

H20 = Water HC = Hydrocarbon

HEGO = Heated Exhaust Gas Oxygen Sensor

HEI = High Energy Ignition

Hg = Mercury

HO2S = Heated Oxygen Sensor

hp = Horsepower

HT = High Tension

IAC = Idle Air Control

IAT = Intake Air Temperature

IATS = Intake Air Temperature Sensor

IC = Integrated Circuit

ICM = Ignition Control Module

ICS = Idle Control Solenoid

ID = Inside Diameter

IFI = Indirect Fuel Injection

IGN = Ignition

ISC = Idle Speed Control

ISO = International Standards Organization

ITCS = Ignition Timing Control System

ITS = Idle Tracking Switch

JAS = Jet Air System kHz = Kilohertz

Km = Kilometres

KOEC = "Key On, Engine Cranking"

KOEO = "Key On, Engine Off"

KOER = "Key On, Engine Running"

kPa = Kilopascals

KS = Knock Sensor

KV = Kilovolts

L = Litres lb.

ft. = Pound Feet

LCD = Liquid Crystal Display

LED = Light Emitting Diode

LHD = Left-Hand Drive

LTFT = Long Term Fuel Trim

LWB = Long Wheel-Base

MAF = Mass Air Flow

MAP = Manifold Absolute Pressure

MAT = Manifold Air Temperature

MCS = Mixture Control Solenoid

MCT = Manifold Charge Temperature

MFI = Multi Port Fuel Injection

MIL = Malfunction Indicator Light

mm = Millimetres

MPFI = Multi Point Fuel Injection

MPG = Miles Per Gallon

MPH = Miles Per Hour

MPI = Multi Port Injection

MPV = Multi-Purpose Vehicle
ms = Millisecond

mV = Millivolts
Nm = Newton Metres

NOX = Oxides of Nitrogen
NVRAM = Nonvolatile Random Access Memory

O2 = Oxygen
O2S = Oxygen Sensor
OBD = Onboard Diagnostics
OBD I = Onboard Diagnostics One

OBD II = Onboard Diagnostics Two

OD = Outside Diameter
OE = Original Equipment
OEM = Original Equipment Manufacturer

OHC = OverHead Camshaft
OHV = OverHead Valve

OS = Oxygen Sensor

P/B = Power Bakes
P/N = Part Number

PA = Pressure Air
PAIR = Pulsed Secondary Air Injection

PAS = Power-Assisted Steering
PCM = Powertrain Control Module

PCV = Positive Crankcase Ventilation
PECV = Power Enrichment Control Valve

PFI = Port Fuel Injection
PID = Parameter ID
PIP = Profile ignition pickup

PNP = Park/Neutral Switch

PPM = Parts Per Million
PROM = Program Read Only Memory (chip)

PS = Power Steering
PSI = Pounds Per Square Inch

PSP = Power Steering Pressure

pt. = Pint
PTC = Pending Trouble Code

PWR = Power to Weight Ratio

Qt. = Quart
RAM = Random Access Memory

RFI = Radio Frequency Interference

RHD = Right-Hand Drive
ROM = Read Only Memory

RON = Rated Octane Number

RPM = Revolutions Per Minute

RWD = Rear-Wheel Drive
SC = Supercharged
SEFI = Sequential Electronic Fuel Injection

SES = Service Engine Soon (light)
SFI = Sequential Fuel Injection
SIPS = Side Impact Protection System

SOHC = Single Over Head Camshaft

SRS = Secondary Restraint System
SRS = Supplemental Restraint System (air bag)

SRT = System Readiness Test
SS = Speed Sensor
SSI = Solid State Ignition

STFT = Short Term Fuel Trim
SWB = Short Wheel-Base

TACH = Tachometer
TB = Throttle Body
TBI = Throttle Body Injection

TC = Turbocharged
TCC = Torque Converter Clutch
TCM = Transmission or Transaxle Control Module

TD = Turbo Diesel
TDC = Top Dead Centre
TDI = Turbo Direct Injection (A turbo charged direct injected diesel engine)

TIV = Thermactor Idle Vacuum Valve
TKS = Throttle Kicker Solenoid

TPI = Tuned Port Injection
TPP = Throttle Position Potentiometer

TPS = Throttle Position Sensor
TPT = Throttle Position Transducer

TSP = Throttle Solenoid Positioner

TV = Throttle Valve
TVS = Thermal Vacuum Switch

TWC = Three Way Catalyst
TWC+OC = Three Way + Oxidation Catalytic Converter

V = Volts
VAC = Vacuum
VAC = Volts Alternating Current

VAF = Volume Airflow
VAF = Vane Airflow Sensor
VCC = Viscous Converter Clutch

VCM = Vehicle Control Module

VDC = Volts Direct Current
VIN = Vehicle Identification Number

VR = Voltage Regulator
VS = Vehicle Sensor
VSS = Vehicle Speed Sensor

VVC = Variable Valve Control

VVT = Variable Valve Timin
WOT = Wide Open Throttle

Christian Rosu


Battery Voltage Dropout

In EMC &quot;dropout&quot; means Battery drops to 0V. FMC1278R3 (CI 260) is an example of various combinations

In EMC "dropout" means Battery drops to 0V. FMC1278R3 (CI 260) is an example of various combinations of such battery voltage dropouts. The problem is that no automotive battery can really drop its output to 0V for say 5 seconds as well as for 50 ms without to blowout a fuse.

 Therefore the only way to simulate correctly a “battery drop to 0V” is to disconnect DUT's B+ line from battery. The test equipment offers such capability to momentarily disconnect the battery during “voltage dropout” simulating a “0V” like condition, practically no current through supply lines to DUT.

This involves the use of PFM200N + VDS200Q + AutoWave to generate the CI 260 type of pulses. PFM200N acts like a very fast switcher disconnecting its output from DUT. So far only FCA (CS.00054) figure it out to ask “open condition” during “0V” battery voltage dropouts. 

In EMC we use the wording “voltage dip” to describe a momentary battery voltage drop (e.g. 4.5V) below minimum supply voltage (e.g. 9V). Obviously in this scenario the Battery B+ line is not disconnected from DUT during the “voltage dip to 4.5V” of 100ms.


Christian Rosu Feb 17, 2021

DUT Activation & Monitoring Software

12. January 2021 15:51 by Christian in EMC/EMI, EMC TEST PLAN, Test Methods
The DUT Performance Functional Verification&amp;nbsp;is based on a bench test software that does not acc

The DUT Performance Functional Verification is based on a bench test software that does not account for EMC specific considerations and is normally performed prior and following each EMC test method.

Using the same Activation & Monitoring Method and Pass/Fail Criteria for ENV and EMC is not practical. DUT’s functions must be grouped in “operating modes” that are in line with the scope of EMC Test Method. When assessing the level of RF emissions we want the DUT to exhibit the highest level of noise possible as in vehicle. During RF Immunity evaluation we expect the following from a good activation/monitoring software:

  • Capability to activate and have realistic data traffic on all I/O lines as well as individual I/O lines.
  • Electrical Transients or RF coupled in supply voltage and I/O lines may not always trigger repeatable anomalies. Therefore we need a visible flag/indicator to immediately stop the actual EMC test method process for anomaly thresholding (e.g. level vs frequency). As we reduce applied stress level the DUT’s behavior may change, then at some point the anomaly should disappear.
  • The same DUT operating mode may be feasible for one or more EMC test methods but definitely not for the entire test list. We need capability to configure what functions belong to each operating mode including live monitoring method. Log files are not useful during test, we still need them following the test for troublesooting. 
  • All functions must resemble vehicle intent usage. Not all I/O lines will be active simultaneously in vehicle. Therefore do not use unrealistic I/O cables scenarios to facilitate testing since this can generate false current loops and other issues.
  • The functions used by DUT activation & Monitoring Software are not meant to assess complaince to USB, E-Net, LVDS standards.

 Keep in your mind that:

  1. Electrical Transients on supply lines can hard reset the MCU (e.g. dips/dropouts). Is there a test in your monitoring software that captures such condition?  Any other anomaly is not relevant once a hard reset occurs.
  2. Do you have a function to verify that there is no memory loss following inadvertent hard/soft reset?
  3. The RF can be coupled in both supply lines and I/O lines resulting in data traffic interruptions leading to a soft reset. Is there a monitoring function to capture such event?
  4. If CAN bus is used in a design I would consider at minimum two critical errors: CAN BUSOFF & DTC SET. What we normally use is a pass fail criteria that can be adjusted such that is possible to determine if the anomaly occurs with every data transmission attempt or it happens only each 100/1000 attempts.

DUT support software

Do not waste time/money to tweak operating modes during EMC validations. In many EMC labs the cost for one hour of ALSE chamber is $500 regardless to how you spend this time. The operating mode must be pre-selected, yet adjustable if needed during troubleshooting. The "anomaly found" visual indicator is used by EMC test operator to stop the actual EMC test software. If we have a time stamp in log files, there is no need to stop the activation/monitoring support software.

DUT Activation Dwell Time

All functions within the same operating mode must be completed and repeated every 2 seconds. We call these 2 seconds Dwell Time, and it can make a huge difference in test duration and cost. For a 2-second dwell time and only one Operating Mode you can expect RF Immunity in ALSE chamber to last 4-5 days (one shift). For a 4-second dwell time it may last practically 8-9 days and so on. Bottom line, if the initialization of Load Simulator or DUT is time consuming it will cost a fortune to re-initialize following each incident/anomaly. Hard/soft reset must always be the last resort to resume operation. The goal is to minimize the number of operating modes and DUT orientations.

Types of DUT support software 

  • Load Simulator EMC support testing software with specific sections for each Operating Mode.
  • Load Simulator Functional/Parametric verification testing done before and after each Test Method.
  • Full DUT Functional/Parametric testing before and after full EMC validation that is not typically done using the EMC Load Simulator but rather EOL like testers.

 DUT Operating Mode

Ideally is to include in Operating Modes only those DUT functions that are active while driving the vehicle. Functions used for diagnostics at the car dealer shop are not relevant. The worst case scenario is when vehicle is in Run Mode (speed >0) but we also have to simulate the Standby Mode (speed = 0) and Sleep Mode (current consumption < 1 mA).

Christian Rosu, Jan 12, 2021