A Comparison of SMD and Through-Hole Components on Conducted Noise Emission

Switched-mode DC-DC converter circuits create quite challenging electromagnetic compatibility problems. Additionally, the design preferences directly affect the EMC performance of the circuits. The study focuses on the conducted noise emissions of the same Boost converter circuits constructed with two different types of assembly technologies, Through-Hole and SMD. For this purpose, two Boost converter circuits using the same integrated circuit, LT1070, were designed by using Through-hole and SMD assembly technologies. The conducted emission measurements were taken according to Class B of EN 55032 standard requiring measuring the noise emission in the frequency range between 150 KHz and 30 MHz. The results obtained from measurements show that the emission amplitude at 160 kHz for Boost converter constructed with Through-Hole components is higher than the standard requirement while the converter constructed with SMD components meets the standard at the same frequency. The conducted emission amplitudes of both Boost converter at 200 KHz and 240 KHz cannot meet the requirements of the standard, but the peak values for SMD-based circuit are higher than the emission amplitudes of Boost converter constructed with Through-Hole components at the same frequencies. Because of failing both circuits on the tests of En 55032 standard, a low-pass π type filter was designed. After adding the π filter to the Boost converter circuits, the conducted emission values have met the standard requirements in all frequency range. The efficiency of the designed filter completely suppresses the noise all frequency range of EN 55032, from 150 KHz to 30 MHz