Patent ID: 8625251
Filing Date: 2014-01-07
Classification: H02M

Abstract:
1. An EMI capacitor discharger, comprising: a first input port and a second input port configured to receive an input AC signal; an EMI capacitor coupled between the first input port and the second input port; a bridge rectifier having a first input terminal, a second input terminal, and an output terminal, wherein the first input terminal is coupled to the first input port, the second input terminal is coupled to the second input port, and wherein the bridge rectifier provides a rectified signal at the output terminal; a zero crossing detector configured to monitor a zero crossing of the input AC signal, and to generate a zero crossing logic flag signal based thereupon; a regulator coupled to the output terminal of the bridge rectifier to receive the rectified signal, and wherein based on the rectified signal, the regulator provides a regulated signal; a timer having a first input terminal, a second input terminal, and an output terminal, wherein the first input terminal is coupled to the regulator to receive the regulated signal, the second input terminal is coupled to the zero crossing detector to receive the zero crossing logic flag signal, and based on the regulated signal and the zero crossing logic flag signal, the timer generates a timeout signal at the output terminal; a logic circuit having a first input terminal, a second input terminal, and an output terminal; wherein the first input terminal is coupled to the output terminal of the timer to receive the timeout signal, the second input terminal is coupled to the output terminal of the zero crossing detector to receive the zero crossing logic flag signal, and based on the timeout signal and the zero crossing logic flag signal, the logic circuit generates a control signal; and a discharge unit having a first terminal, a second terminal, and a control terminal, wherein the first terminal is coupled to the output terminal of the bridge rectifier, the second terminal is coupled to a floating reference ground, and the control terminal is coupled to the output terminal of the logic circuit to receive the control signal, to controllably discharge the EMI capacitor.