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:
Apr. 28, 1998
Filed:
Sep. 05, 1996
Lee E Leppo, Tallmadge, OH (US);
Telxon Corp., Akron, OH (US);
Abstract
A monitoring circuit for a Li-Ion battery pack charging apparatus is disclosed. The monitoring circuit modifies charging time for a Li-Ion battery pack inserted in the charging apparatus to compensate for temperature effects on the charging current input to the battery pack. In one embodiment of the monitoring circuit, a comparator is utilized to compare a voltage across the battery pack, V.sub.charge, to a set point voltage value, V.sub.sp. The set point voltage value, V.sub.sp, is taken off a temperature sensor circuit comprising a voltage divider circuit. The voltage divider circuit includes at least one thermistor in a ground connected leg of the divider. In a second embodiment of the monitoring circuit of the present invention, a differential amplifier is coupled to opposite ends of a low resistance sensor resistor. The sensor resistor is coupled between charging circuitry and the Li-Ion battery pack to be charged. The voltage differential across the resistor, V.sub.sensor, is amplified by a gain of the differential amplifier. A gain adjusted differential voltage, V.sub.gsensor, is compared by a microprocessor to a set point voltage value, V.sub.sp. The set point voltage value, V.sub.sp, is generated by a temperature sensor circuit. The temperature sensor circuit includes a voltage divider circuit and the set point voltage value, V.sub.sp, is taken off the voltage divider which includes at least one thermistor in a ground connected leg of the divider.