The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Nov. 01, 2011
Filed:
Oct. 29, 2009
Yong LI, Campbell, CA (US);
Carrie Seim, Campbell, CA (US);
Junjie Zheng, Santa Clara, CA (US);
John W. Kesterson, San Jose, CA (US);
Liang Yan, Milpitas, CA (US);
Clarita Poon, Pleasanton, CA (US);
Fuqiang Shi, Cupertino, CA (US);
Yong Li, Campbell, CA (US);
Carrie Seim, Campbell, CA (US);
Junjie Zheng, Santa Clara, CA (US);
John W. Kesterson, San Jose, CA (US);
Liang Yan, Milpitas, CA (US);
Clarita Poon, Pleasanton, CA (US);
Fuqiang Shi, Cupertino, CA (US);
iWatt Inc., Los Gatos, CA (US);
Abstract
Adaptive multi-mode digital control schemes that improve the light-load efficiency (and thus the overall average efficiency) in switch-mode power converters without causing performance issues such as audible noises or excessive voltage ripples. Embodiments include a switch-mode power converter that reduces current in the power converter using a second pulse-width-modulation (PWM) mode before reaching switching frequencies that generate audible noises. As the load across the output of the power converter is reduced, the power converter transitions from a first PWM mode in high load conditions to a first pulse-frequency-modulation (PFM) mode, then to a second PWM mode, and finally to a second PFM mode. During the second PFM mode, the switching frequency is dropped to audible frequency levels. Current in the power converter, however, is reduced in the second PWM mode before transitioning to the second PFM mode. Therefore, the power converter produces less or no audible noise in light load conditions where the switching frequency drops to audible frequency levels, while achieving high efficiency across varying load conditions.