The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 19, 1999
Filed:
Nov. 28, 1997
Yokogawa Electric Corporation, Tokyo, JP;
Abstract
A switching power supply apparatus wherein a main converter turns 'on' and 'off' a DC current applied to a primary winding of a main transformer using a main switching element and outputs a main output voltage to the secondary side after rectifying and smoothing current induced in a secondary winding; an error amplifier generates an error voltage between the main output voltage and a first reference voltage; a PWM control circuit outputs an on-off control signal for the main switching element so that the error voltage is minimized; a photo coupler receives the error voltage and provides an output to the PWM control circuit; an over-voltage protection circuit generates an over-voltage protection signal when the main output voltage exceeds a second reference voltage; an on-off circuit outputs either a high level potential or a common level potential depending on whether the power is to be turned 'on' or 'off'; a shut down latch circuit outputs a shut down signal when the over-voltage protection signal represents an over-voltage state; and a shut down implementation circuit holds the input voltage to the photo-coupler at a value which suppresses input to the photo-coupler when a signal from the on-off circuit specifies power off or when the shut down signal from the shut down latch circuit is effective; whereby only a single isolator is required in the apparatus.