| 摘要 |
PROBLEM TO BE SOLVED: To reduce ringing noise without increasing the number of parts in a printed circuit board which mounts a switching power supply. SOLUTION: A print pattern 5 has a spiral structure, one end of which is connected to an integrated circuit IC by a bonding wire 6, and the other end is connected to a solid ground GND by a point 7. The length of the print pattern 5 is lengthened by taking the spiral structure, and a low-pass filter is constituted by increasing a parasitic inductance between a source terminal of a synchronous rectification switch and an output capacitor Cout and by increasing a parasitic capacitance Cp with the solid ground GND. The ringing noise is reduced by the low-pass filter. COPYRIGHT: (C)2009,JPO&INPIT
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