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:
Jul. 23, 1985
Filed:
Aug. 18, 1983
Philip A Hoffman, Towson, MD (US);
Solid State Chargers Research and Development Limited Partnership, Lutherville, MD (US);
Abstract
A battery charger which includes terminals for connection to an electric power source, an electrical charging circuit and an operative arrangement for connecting at least one rechargeable battery cell in series with the charging circuit across the terminals. The battery charger has a charging circuit which includes a first resistor, a second resistor, a third resistor and a rectifier, constituted by at least one diode, in series. A first transistor, which has a collector-emitter path and a base-emitter path, is operatively connected so that the base-emitter path is connected in parallel with the first resistor. A fourth resistor is provided, the fourth resistor being connected in series with the collector-emitter path of the transistor and the third resistor. In one species, a plurality of additional transistors, connected in Darlington configuration, includes a second transistor and a final transistor, each of the additional transistors having its collector connected to a circuit point between the third resistor and an electrode of the diode. The first transistor and the last transistor in the one species have their emitters connected via a current-limiting PTC fifth resistor which may act as a fuse. The first transistor and the second transistor have their respective collector and base conductively connected. In another species, a field effect transistor, preferably a MOSFET, is used instead of the Darlington configuration. The connection of the third resistor provides internal feedback. The fifth resistor, when in series with the first resistor in the base-emitter circuit, provides external feedback.