US 6,982,882 B2
High voltage charging circuit for charging a high voltage capacitor
Yi-Shan Chu, Hsinchu (Taiwan); Ming-Nan Chuang, Hsinchu (Taiwan); and Yuan-Wen Chang, Hsinchu (Taiwan)
Assigned to Leadtrend Technology Corporation, Hsinchu (Taiwan)
Filed on Aug. 17, 2004, as Appl. No. 10/919,301.
Claims priority of application No. 92130231 A (TW), filed on Oct. 30, 2003.
Prior Publication US 2005/0094419 A1, May 05, 2005
Int. Cl. H02M 3/335 (2006.01)
U.S. Cl. 363—21.01 8 Claims
OG exemplary drawing
 
1. A high voltage charging circuit for charging a high voltage capacitor, comprising:
a direct current power source for outputting a large current with a low voltage value;
a transformer for transforming the large current with a low voltage value into a small current with a high voltage value for output;
a diode for inputting the small current with a high voltage value and then outputting the small current with a high voltage value to the high voltage capacitor to charge the high voltage capacitor;
a power transistor; wherein when the power transistor is turned on, the transformer transforms the large current with a low voltage value but does not output the large current with a low voltage value; when the power transistor is turned off, the transformer stops transforming the large current with a low voltage value and outputs the large current with a low voltage value;
an activation control circuit for controlling an ON time period of the power transistor; and
an inactivation control circuit for controlling an OFF time period of the power transistor; wherein
the activation control circuit and the inactivation control circuit control the ON time period or the OFF time period of the power transistor by controlling a positive output signal from a positive end of a flip flop.