SNOAA88 June   2022 LDC3114 , LDC3114-Q1

 

  1.   Abstract
  2.   Trademarks
  3. 1Introduction
    1. 1.1 Inductive Sensing
    2. 1.2 EMI
  4. 2CISPR 25 Requirements
    1. 2.1 Radiated EMI Testing
      1. 2.1.1 Test Setup
      2. 2.1.2 Test Results
    2. 2.2 Conducted EMI Testing
      1. 2.2.1 Test Setup
      2. 2.2.2 Test Results
  5. 3Summary
  6. 4References

2.2.2 Test Results

The first test done is to get a baseline of the EVM without the sensor coil included. The baseline test shown in Figure 2-11 only has the EVM with the battery connected.

GUID-20220412-SS0I-BXCG-XNLM-TVTL6TFKCB3K-low.png Figure 2-11 Conducted Test Baseline

Next, a 7-MHz sensor coil is attached to the EVM and the test is run again, see the results in Figure 2-12.

GUID-20220412-SS0I-X0QV-QQ98-K2H796TVHLTB-low.png Figure 2-12 Conducted Test With 7-MHz Sensor Coil

The added sensor coil has a significant impact on the test performance but the test still passes. A similar result also occurs when the coil is replaced with a 12.6-MHz coil, see Figure 2-13.

GUID-20220412-SS0I-JCRD-LB13-XQBHGPJZT45W-low.png Figure 2-13 Conducted Test With 12.6-MHz Sensor Coil

The frequency of the spikes in the test data increased as the coil frequency increased. Because of this, the coil frequency is an important part of the design when considering other EMI noise sources or any keep-out-regions for the system requirements.