SIGNAL TRANSMISSION TRANSFORMER FOR SWITCHING POWER SUPPLY AND SWITCHING POWER SUPPLY DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a signal transmission transformer for switching power supply device in which adjustment of the inductance and the degree of coupling is facilitated, and to provide a switching power supply device with high safety.SOLUTION: A signal transmission transformer 22 includes concentric coil patterns 52(3)-52(6) formed on a conductor layer 52 in a multilayer substrate 50 on which a switching power supply circuit is configured by mounting circuit elements. A pair of closure patterns 52(2), 52(7) are provided on the outside conductor layers 52 sandwiching the coil patterns 52(3)-52(6), and formed so as to close at least one turn of the innermost of the coil patterns 52(3)-52(6) and the inside region thereof. When a current flows through any one of the coil patterns 52(3)-52(6), a part of magnetic flux generated in the inside region of one turn of the innermost is closed by the closure patterns. The closure patterns 52(2), 52(7) are connected to a stable potential.