Patent ID: 8213147
Filing Date: 2012-07-03
Classification: H02H

Abstract:
1. An over-current protection circuit having a first state and a second state, the over-current protective circuit comprising: in the first state: a first transistor having a first control node, wherein, when the first transistor is on, it connects a first supply voltage to an output that draws a load current through the first transistor; a second transistor having a second control node, wherein the second transistor outputs a scaled mirror current of the load current; a control circuit having first and second inputs; the first input connected to a reference input, the control circuit having a control output connected to the first and the second control nodes; a sense circuit that compares the scaled mirror current to a predetermined threshold, wherein when the predetermined threshold is not reached, an output of the sense circuit activates a switch assembly that connects a first signal to the control circuit second input, wherein the control output drives the first and the second transistors on; wherein when the predetermined threshold is reached, the over current protection circuit assumes the second state, wherein when in the second state: a feedback loop exists where the scaled mirror current connects to the sense circuit, the output of the sense circuit now activates the switch assembly to connect a feedback signal, generated from the scaled mirror current, to the control circuit second input signal, wherein the control output drives the first and second switches into an analog condition, wherein the load current and the scaled mirror currents are lowered until the feedback signal matches the reference input.