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1. (WO2015045074) STEP-DOWN POWER SUPPLY CIRCUIT, POWER SUPPLY MODULE, AND STEP-DOWN POWER SUPPLY CIRCUIT CONTROL METHOD

Pub. No.:    WO/2015/045074    International Application No.:    PCT/JP2013/076135
Publication Date: Fri Apr 03 01:59:59 CEST 2015 International Filing Date: Fri Sep 27 01:59:59 CEST 2013
IPC: G05F 1/56
H02M 3/155
Applicants: FUJITSU LIMITED
富士通株式会社
Inventors: NAKAMOTO, Hiroyuki
中本 裕之
Title: STEP-DOWN POWER SUPPLY CIRCUIT, POWER SUPPLY MODULE, AND STEP-DOWN POWER SUPPLY CIRCUIT CONTROL METHOD
Abstract:
Provided is a step-down power supply circuit (20), comprising: a first PMOS transistor (37), a source thereof connected to a voltage input (151), and a drain thereof connected to a voltage output (152); a control circuit (21) which operates by a voltage of an internal voltage line (153), and controls the gate voltage of the first PMOS transistor (37); a comparator (23) which operates by the voltage of the internal voltage line (153), and changes the output from a first state to a second state when the voltage of the voltage input (151) falls; switch circuits (26, 27) which connect the voltage input (151) to the internal voltage line (153) when the output of the comparator (23) is in the first state, and which connect the voltage output (152) to the internal voltage line (153) when the output of the comparator (23) is in the second state; and cutout circuits (31, 38) which, when the output of the comparator (23) is in the second state, cut out a current backflow path from the voltage output (152) to the voltage input (151) via the first PMOS transistor (37).