(52) U.S. CI 323/284; 323/285
(58) Field of Classification Search 323/282 288,
323/351, 222, 224, 225, 268, 272; 363/16, 363/17, 20, 19,21.7 See application file for complete search history.
(56) References Cited
U.S. PATENT DOCUMENTS
5,959,441 A 9/1999 Brown 323/282
6,137,240 A 10/2000 Bogdan 315/307
6,215,288 Bl * 4/2001 Ramsey et al 323/224
6,313,616 Bl 11/2001 Deller et al 323/282
RE37,609 E * 3/2002 Bittner 323/272
6,366,070 Bl 4/2002 Cooke et al 323/284
6,396,252 Bl * 5/2002 Culpepper et al 323/285
* cited by examiner
Primary Examiner—Rajnikant B. Patel
(7'4) Attorney, Agent, or Firm—Grossman, Tucker, Perreault
& Pfleger PLLC
(57) ABSTRACT
A method includes starting a time count of a time interval at a start of a state change of a switch of a DC to DC converter; monitoring if the switch is in a skip mode; and disabling the skip mode in response to an expiration of the time interval so that the switch changes states at a frequency rate greater than an audible frequency for humans.
16 Claims, 11 Drawing Sheets
