POWER SUPPLY CIRCUIT, POWER SUPPLY SYSTEM, AND PORTABLE TERMINAL DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a power supply device capable of stably supplying a power supply voltage without damaging the stability of a circuit as a power supply destination.SOLUTION: A power supply circuit (1) includes: an input terminal (PIN) to which a voltage is supplied; a linear regulator (10) which drops and outputs an input voltage (VBAT); a monitoring part (12) which monitors the voltage supplied to the input terminal; a detection part (13) which detects that the voltage supplied to the input terminal is less than a reference value on the basis of the monitor result of the monitoring part; and a control part (11) which controls the supply of the input voltage to the linear regulator. The control part blocks the supply of the input voltage to the linear regulator when the detection part detects that the voltage supplied to the input terminal is less than the reference value.