POWER SUPPLY DEVICE WITH SIGNALING FACILITY

PROBLEM TO BE SOLVED: To solve the following problem associated with power supply devices that uses a transformer and the secondary side and the primary side of which are insulated from each other: to transfer a signal from the secondary side to the primary side, such an element as an insulating element must be added aside from the power supply device; therefore, components are concentrated on an insulated portion and the packaging density of a printed board cannot be made uniform. SOLUTION: The resistance value of a load connected to the secondary side, the number of turns on the secondary side, or the inductance of a smoothing coil is varied by a signal to be transferred. The current value on the primary side obtained as the result of the variation or the duty ratio or pulse width of the control pulse signal of a switch for connecting/disconnecting the primary current is detected to regenerate a signal. This makes it possible to transfer a signal from the secondary side to the primary side just by adding a very small number of components. COPYRIGHT: (C)2009,JPO&INPIT