| 摘要 |
PROBLEM TO BE SOLVED: To prevent conversion efficiency from being lowered even if a load current is reduced by constituting a switching element of a plurality of MOSFETs through which an output current is passed. SOLUTION: In a synchronous rectification step-down converter, a semiconductor switch QP is formed by connecting drains and sources of n transistors Qp1 to Qpn and a board in common and connecting divided gate terminals with a P-channel MOSFET gate drive circuit 1 independently. N-channel MOSFETs Qn1 to Qnn constitute a semiconductor switch QN wherein the respective gate terminals are connected with a N-channel MOSFET gate drive circuit 2 and drains and sources thereof are connected in common with a diode D for commutation. Load determining signals Vload outputted from a load determining circuit 5 switch the transistors Qp1 to Qpn and Qn1 to Qnn switches an enable state wherein the turn-on/off of each individual transistor is controlled to a disable state wherein the transistors are kept off. COPYRIGHT: (C)2004,JPO |
