Patent ID: 8184457

Claim:
A switch mode power supply ( 15 ), comprising: a rectifier ( 20 ) operable to generate a rectified supply voltage (V RS ) based on an in-line voltage (V LN ); a converter ( 50 ) in electrical communication with the rectifier ( 20 ) to convert the rectified supply voltage (V RS ) to a DC bus voltage (V DC ), wherein the converter ( 50 ) includes a transient voltage suppression device ( 52 ) operable to suppress the rectified supply voltage (V RS ) in response to an abnormal line condition of the switch mode power supply ( 15 ); wherein the converter ( 50 ) further includes an electronic switching device ( 51 ); and a transient voltage sensing device ( 16 ) operable to facilitate the electronic switching device ( 51 ) being driven to a nonconductive state in response to the abnormal line condition of the switch mode power supply ( 15 ); wherein the rectifier ( 20 ) includes a rectifier output capacitor (C 2 ) and the rectified supply voltage (V RS ) is generated across the rectifier output capacitor (C 2 ); wherein the converter ( 50 ) further includes a converter output capacitor (C 3 ) and the DC bus voltage (V DC ) is generated across the converter output capacitor (C 3 ); and wherein the transient voltage suppression device ( 52 ) includes a varistor (V 3 ) operable to facilitate an exchange energy from the rectifier output capacitor (C 2 ) to the converter output capacitor (C 3 ) based on the electronic switching device ( 51 ) being driven to the nonconductive state in response to the abnormal line condition of the switch mode power supply ( 15 ).