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:
Dec. 23, 1997
Filed:
May. 03, 1996
Sergiu Silvian, La Crescenta, CA (US);
Pacesetter, Inc., Sylmar, CA (US);
Abstract
The on time of a flyback converter is controlled without the need for a current-sensing resistor. Under one approach, an internal battery resistance R.sub.B is used as a substitute for the current-sensing resistor. The battery voltage V.sub.B decreases as a function of current drain from the battery due to the internal impedance. Charging control circuitry causes the on time to be terminated when the battery voltage V.sub.B falls below a predetermined reference voltage V.sub.R, where V.sub.R =V.sub.B1 -.DELTA..DELTA.V.sub.B. V.sub.B1 represents the battery voltage before charging is commenced, and .DELTA.V.sub.B represents the drop in battery voltage from V.sub.B1 when the battery current drain exceeds a predetermined maximum current. Under another approach, the charging control circuitry regulates the time out period t.sub.on1 =K/V.sub.B, where K is a predetermined constant, such that it is 10-15 percent longer than the on time t.sub.on.