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:
May. 18, 2004
Filed:
Apr. 16, 2002
Seiko Instruments Inc., Chiba, JP;
Abstract
In a charge pump circuit, a constant current circuit is disposed between an input power supply and an output capacitor, when a power supply is started to turn on, the operation of the charge pump circuit is stopped, and the output capacitor is charged up to a given voltage by the constant current circuit, and thereafter the normal operation of the charge pump is started to limit the rush current. When the power supply is started, the operation is conducted by an oscillator circuit having a small duty ratio, and thereafter the control is replaced by the PFM control having the normal duty ratio, to thereby reduce the rush current as compared with that of the conventional PFM control. When the power supply is started, a pre-driver including a current limiting element is used to drive a driver, resulting in such an advantage that the rush current is reduced as compared with that driven by the conventional pre-driver.