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:
Oct. 24, 2000
Filed:
Jan. 22, 1999
Barry K Kates, Austin, TX (US);
John Cummings, Round Rock, TX (US);
Dell Computer Corporation, Round Rock, TX (US);
Abstract
A limiting circuit for controlling overshoot in a charge current in a battery recharging system includes a current amplifier receiving input indicative of charge current in a rechargeable battery circuit and generating a current error signal, a voltage amplifier receiving input indicative of charge voltage in the rechargeable battery circuit and generating a voltage error signal, and a power amplifier receiving a first signal indicative of power in a switching voltage regulator and a second power signal indicative of power in the rechargeable battery circuit, and generating a power error signal. The limiting circuit compares the voltage error signal, the current error signal, and the power error signal to determine the error signal having the greatest value, and generates an input signal to a pulse width modulation comparator. The limiting circuit also includes an internal current source, a first transistor coupled to the current amplifier, a second transistor coupled to the voltage amplifier; and a third transistor coupled to the power amplifier. The first transistor, the second transistor, and the third transistor are coupled to the internal current source to determine the error signal having the greatest value. To prevent reverse current flow in the switching voltage regulator, a low current comparator receives a signal indicative of the current flowing in the switching voltage regulator, and generates an output signal. A transistor receives the output signal from the low current comparator, and generates a signal to maintain the current flowing in the switching regulator circuit above a threshold value.