[muRata] EMC Solutions: Noise Suppression Examples

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Minimizing the GND’s noise level is important in the interface cable connection. The PCB’s GND and metal case are screwed together to form a low-impedance connection at high frequency.

EMI filters are installed in the interface cable connection. Note that the CD-ROM drive may not operate on some computers if large-capacitance or large-inductance EMI filters are used.

Noise Emission Status
Noise Suppression Model

Installing EMI Filters on the Headphone Output Port
Installing EMI Filters on the Clock Line
Installing EMI Filters on Bus Lines
Installing EMI Filters on Oscillator Output
Installing EMI Filters on Interface Cable Ports
Installing EMI Filters on the DC Power Supply Input and Line

Noise suppression on the Power Supply connector line using the
NFM41PC204F1H3 (Chip Solid EMIFIL®, 0.2 µ F)

Before installing the EMI filter			High frequency noise stemming from the CPU or memory inside the CD-ROM drive is conducted to the AC adapter cable through the power supply line and emitted from the cable. When the NFM41PC204F1H3 (Chip Solid EMIFIL®, 0.2 µ F) is installed on the power supply connector line, noise level is suppressed by 4 to 5 dB. Generally, the power supply input uses an electrolytic capacitor or the like for decoupling. However, it cannot suppress high frequency noise satisfactorily. Using a three-terminal capacitor with a high capability for high frequency noise suppression is most effective.
After installing the EMI filter