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CISPR 25:2016 CEV Limits

Table 5 – Examples of limits for conducted disturbances – Voltage method

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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

Understanding CISPR 25 Voltage Method (CEV)

The voltage method in CISPR 25 is used to measure conducted disturbances on power supply lines of automotive components. Unlike the current probe method which measures common-mode current, the voltage method typically uses an Artificial Network (AN) or LISN (Line Impedance Stabilization Network) to measure the noise voltage directly.

Key Differences from Current Probe Method:

  • Measurement Unit: Limits are defined in dB(µV) instead of dB(µA).
  • Setup: Requires direct connection to the LISN RF port.
  • Application: Primary method for ensuring that component noise does not interfere with the vehicle's electrical system via power lines.

Note for Engineers: CISPR 25 Class 5 is the most stringent level, typically required for components located near sensitive radio receivers.