Power supply apparatus
AssigneeMatsushita Electric Industrial Co., Ltd.
InventorsTsutomu Nakanishi, Tsuneo Tsuji
Life of this patent
Estimating the term…
Abstract
In a power supply apparatus having voltage doubler rectifier circuit (5) connected to secondary winding (1B) of transformer (1), diode (13) is connected between transistor (3) and primary winding (1A) of transformer (1). By detecting an AC voltage at a junction point between primary winding (1A) of transformer (1) and diode (13) thereby performing over-voltage protection, the difference between the maximum operating voltage and the no-load operating voltage is decreased and the voltage during no-load operation is lowered and thus small-sized power supply apparatus and peripheral equipment can be provided.
Claims3
A power supply apparatus comprising:
- a transformer having a primary winding and a secondary winding;
- a first DC power source connected with one terminal of said primary winding of said transformer;
- a diode having its anode connected with the other terminal of said primary winding of said transformer;
- a switching element connected between the cathode of said diode and the ground;
- a voltage doubler rectifier circuit connected with said secondary winding of said transformer;
- a current detector for detecting a DC current from said voltage doubler rectifier circuit;
- a control circuit for controlling said switching element in accordance with an output from said current detector;
- an AC voltage detector connected in parallel between a junction point between the anode of said diode and the other terminal of said primary winding of said transformer and the ground;
- and
- a limiter for controlling said switching element when the output of said AC voltage detector exceeds a predetermined voltage value thereby limiting voltage of said secondary winding of said transformer.
Dependencies are inferred from the claim text.