AC ADAPTER WHICH CAPABLE OF REDUCING POWER AT NON-USE AND BATTERY DRIVEN-TYPE ELECTRONIC UNIT

摘要

PROBLEM TO BE SOLVED: To provide a superior AC adapter which is capable of reducing power at the time of non-use and a battery driving-type electronic unit which can use the AC adapter. SOLUTION: An AC adapter 10 is provided with a first conversion circuit 12 for converting inputted AC voltage into DC voltage having a first voltage level and outputting it to an output line, a switch 20 provided for the primary side of the first conversion circuit, a second conversion circuit 31 for converting inputted AC voltage into a second voltage level higher than the first voltage level and outputting it to the output line, and an AC adapter operation control circuit 32 for comparing the voltage level on the output line with a reference voltage which is higher than the first voltage level and lower than the second voltage level, turning on the switch when output voltage becomes less than reference voltage, and turning off the switch when output voltage exceeds the reference voltage. When the demand for power voltage does not exist on an electronic unit-side, voltage on the output line exceeds reference voltage and the operation of the first conversion circuit 12 is stopped.