Patent ID: 6418222
Filing Date: 2002-07-09
Classification: H02H,H04M

Abstract:
A protection circuit comprising:input terminals arranged to be coupled to a source of electrical energy; output terminals arranged to be coupled to an output circuit to be protected; a variable impedance device coupled in a current flow path between said input and output terminals, and through which all current flowing into said input terminals from said source of electrical energy flows irrespective of the impedance state of said variable impedance device; an overcurrent bypass circuit coupled to receive said all current flowing through said variable impedance device and being operative to controllably cause a portion of said all current flowing through said variable impedance device to be diverted around said output circuit to be protected through a bypass path away from said output circuit; and a current flow sense circuit coupled to monitor current flow through a current flow path through said output circuit and being operative, in response to an overcurrent condition, to cause said overcurrent bypass circuit to controllably divert a first portion of said all current flowing through said variable impedance device to be directed through said bypass path away from said output circuit, while allowing a second portion of said all current flowing through said variable impedance device, and sufficient to operate said output circuit, to continue to flow through said current flow path and said output circuit.