EMI Suppression Filters (EMC and Noise Suppression)Investigation of noise conditions

Measures to suppress noise are implemented as follows based on the investigation results.

Measures were implemented that focus on the suppression of normal mode noise.
→ Insert an LPF near the power connector. (Measure to suppress noise over all frequencies)
[Example] Inductor: LQH5BPZ4R7NT0 + capacitor: GCM188R71E105KA49

The following methods are effective measures for suppressing the noise of a step-down DC-DC converter.
→ Attach a shield to the circuit substrate. (Measure to suppress noise up to 20 MHz)

→ Insert a common mode choke coil (CMCC) immediately next to the power connector. (Measure to suppress common mode noise at 20 MHz or more)
[Example] PLT5BPH5013R1SN

→ Insert an LPF near the power connector. (Measure to suppress normal mode noise at 20 MHz or more)
*This method can be used together with the above measures to suppress conducted noise.

The following methods are effective measures for suppressing the noise of a step-down DC-DC converter.

→ (1) Insert an LPF near the power connector. (Measure to suppress noise over all frequencies)
[Example] LQH5BPZ4R7NT0 + GCM188R71E105KA49

→ (2) Insert a CMCC near the power connector. (Measure to suppress noise at 10 MHz or more)
[Example] PLT5BPH5013R1SN

→ (3) Attach a shield to the circuit substrate. (Measure to suppress noise up to 20 MHz)

→ (4) Insert a CMCC immediately next to the power connector. (Measure to suppress noise at 20 MHz or more)

→ (5) Insert an LPF near the power connector. (Measure to suppress noise at 20 MHz or more)
*Measures (4) and (5) can be used together with measures (1) and (2) above.