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EMC
Index | CISPR 25 ECE R10 EN 55032 / CISPR 32 FCC Part 15
CEV CEC RE

CISPR 25:2016 CEV Limits

Conducted Emission – Voltage Method (Table 5)

This table compiles the Conducted Emission (CEV) voltage method limits (corresponding to Table 5) for automotive components per CISPR 25, including complete data for Class 1-5, suitable for EMC pre-compliance and certification reference.

Limit Visualization Curve
Class:
Filter Table by Class:
Levels in dB(µV). Scroll horizontally to view more.
Service / Band
Frequency MHz
Class 5 Class 4 Class 3 Class 2 Class 1
Peak QP Avg Peak QP Avg Peak QP Avg Peak QP Avg Peak QP Avg
BROADCAST
LW 0.15 to 0.30 70 57 50 80 67 60 90 77 70 100 87 80 110 97 90
MW 0.53 to 1.8 54 41 34 62 49 42 70 57 50 78 65 58 86 73 66
SW 5.9 to 6.2 53 40 33 59 46 39 65 52 45 71 58 51 77 64 57
FM 76 to 108 38 25 18 44 31 24 50 37 30 56 43 36 62 49 42
TV Band I 41 to 88 34 - 24 40 - 30 46 - 36 52 - 42 58 - 48
MOBILE SERVICES
CB 26 to 28 44 31 24 50 37 30 56 43 36 62 49 42 68 55 48
VHF 30 to 54 44 31 24 50 37 30 56 43 36 62 49 42 68 55 48
VHF 68 to 87 38 25 18 44 31 24 50 37 30 56 43 36 62 49 42

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Test Setup & Technical Overview

Detailed engineering guide for Conducted Emissions (CEV) by Voltage Method / LISN Method

Technical Overview: Voltage Method vs. Current Probe

The voltage method (CEV) and current probe method (CEC) are complementary techniques for assessing conducted emissions on power supply lines. While the current probe method (CEC) measures the noise currents, the voltage method (CEV) directly measures the disturbance voltage at the terminals of the Equipment Under Test (EUT).

The LISN/AN (Line Impedance Stabilization Network) acts as a standardized interface, providing a defined RF impedance. CEV is the primary regulatory compliance method for ensuring that component-level emissions do not conduct back into the vehicle's low-voltage electrical distribution system, whereas CEC is more focused on harness radiation characteristics.

Test Configuration & LISN Isolation

For a valid CEV measurement, the EUT is placed on a non-conductive, low-dielectric support 50 mm above the ground plane. A Line Impedance Stabilization Network (LISN) or Artificial Network (AN) is inserted in the power lines.

The LISN isolates the EUT and the measuring receiver from RF noise present on the external power supply, while offering a stable 50 Ω impedance for high-frequency signals. The wiring harness between the EUT and the LISN must be kept to 200 mm.

Interpretation of Limits (Class 1-5)

CISPR 25 specifies five limit classes to accommodate different vehicle environments and installation configurations:

  • Class 5: The most stringent class, typically mandated by OEMs for safety-critical components (ADAS, steering, braking) or devices located near sensitive radio antennas.
  • Class 4 & 3: Applied to standard body electronics, powertrain control units, and infotainment displays.
  • Class 2 & 1: The least severe limits, reserved for simple, transient, or non-critical loads (e.g., seat adjusters, window motors) that present minimal risk to the vehicle's RF receivers.