Patent ID: 7443276
Filing Date: 2008-10-28
Classification: H02M

Abstract:
1. A digital output circuit of a digital system for controlling a load, said digital output circuit comprising: an electromagnetic coupling device separating said digital output circuit into a system side and an output side, said electromagnetic coupling device comprising a system-side electromagnetic coupling element at said system side, and a first output-side electromagnetic coupling element and a second output-side electromagnetic coupling element, both at said output side, said system-side electromagnetic coupling element transfers an electrical signal of said system-side electromagnetic coupling element to a correspond electrical signal across said first and said second output-side electromagnetic coupling elements, and vice versa; a system-side driving circuit powered by an internal power source, said system-side driving circuit connected to said system-side electromagnetic coupling element, said system-side driving circuit having a digital control signal from said digital system and a clock signal as input, said system-side driving circuit having a feedback terminal from which said digital system samples a feedback signal corresponding an electrical status of said output side; and an output-side control circuit connecting to said first output-side electromagnetic coupling element in parallel, said output-side control circuit and said second output-side electromagnetic coupling element and said load series-connected between the positive and negative ends of a external power source and thereby forming a load circuit; wherein, when said digital system outputs an ON digital control signal, said system-side driving circuit causes said internal power source periodically applied to said system-side electromagnetic coupling element, said first output-side electromagnetic coupling element is thereby induced to generate a corresponding electrical signal, said electrical signal drives said output-side control circuit to make said load circuit conductive; and wherein, when said digital system outputs an OFF digital control signal, said system-side driving circuit disengages said internal power source and said system-side electromagnetic coupling element, said first output-side electromagnetic coupling element thereby cannot generates an electrical signal and said load circuit is open-circuited; and wherein, during when said digital system outputs an ON digital control signal and during the periods when said internal power source is not applied to said system-side electromagnetic coupling element, a feedback signal is induced across said system-side electromagnetic coupling element and is sampled by said digital system via said feedback terminal.