Patent ID: 8599182
Filing Date: 2013-12-03
Classification: G09G

Abstract:
1. A power sequence control circuit, receiving an input positive voltage and an input negative voltage, for providing an output positive voltage and an output negative voltage to a driver, comprising: a voltage pull-up stage, having a first terminal coupled to the input positive voltage, a second terminal coupled to a node, and a control terminal receiving a feedback of the output positive voltage; a voltage pull-down stage, having a first terminal coupled to the node, and a second terminal coupled to the output negative voltage; and a current limit switching unit, having a first terminal receiving the input positive voltage, a second terminal outputting the output positive voltage, and a control terminal coupled to the node, wherein the second terminal is only coupled to the control terminal of the voltage pull-up stage and an external device that receives the output positive voltage, wherein when the output negative voltage decreases, the voltage pull-down stage pulls down a control voltage at the node, and when the control voltage is lower than an enabling threshold, the current limit switching unit conducts immediately upon the output negative voltage decreasing to a level and causing the control voltage lower than the enabling threshold, thus to transmit the input positive voltage as the output positive voltage being identical to the input positive voltage, wherein before the current limit switching unit is conducted, the output positive voltage remains at an initial voltage level, wherein the input negative voltage and the input positive voltage are at voltage levels varying in input time sequence but not at fixed voltage levels.