关键词: 低噪声；开关电源；多路输出；噪声抑制；尖峰；电磁辐射

Abstract: The low-noise requirement of switching power supply (SPS) is becoming more and more common, and the power demand is also growing in high-precision electronic systems. According to the noise source and its characteristics of SPS, it is possible to achieve the output of low noise by comprehensive utilization of multiple noise suppression measures. In this paper, a low-noise design of SPS with multiple outputs is introduced emphatically, and the low-noise design of fundamental converter and its peripheral circuit is analyzed. Then, the noise suppression scheme in regard of switching transistor, rectifier, transformer radiation, layout, wiring, outgoing line and common-mode noise is adopted. Finally, a practical circuit is trial-produced by using the scheme, and the results show that the design has met the expected requirements.

Key words: low noise; switching power supply; multiple outputs; noise rejection; spike; electromagnetic radiation