US 7,321,258 B2
Method and apparatus for controlling the charge of a bootstrap capacitor for non-synchronous type DC-DC converter
Shiah Siew Wong, Singapore (Singapore); and Guolei Yu, Singapore (Singapore)
Assigned to Matsushita Electric Industrial Co., Ltd., Osaka (Japan); and Panasonic Semiconductor Asia Pte., Ltd., Singapore (Singapore)
Filed on Jul. 29, 2005, as Appl. No. 11/193,666.
Prior Publication US 2007/0024261 A1, Feb. 01, 2007
Int. Cl. G05F 1/40 (2006.01)
U.S. Cl. 327—589  [323/288] 14 Claims
OG exemplary drawing
 
1. A method for controlling the charge of a bootstrap capacitor for non-synchronous type DC-DC converter, having a power transistor, the method comprising:
comparing a voltage across the bootstrap capacitor with a predetermined threshold level; and
turning on a secondary switch during off-time of said power transistor when the voltage across the bootstrap capacitor is lower than the predetermined threshold and when the light load condition is detected.