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:
Sep. 19, 1989
Filed:
Feb. 06, 1989
Jerzy Borkowicz, Whitburn, CA;
Northern Telecom Limited, Montreal, CA;
Abstract
A solid state switching device allows independent control of the latching and holding currents, and has particular application to telephone systems. The holding current may be set at a high level so as to return the switching device to the off-state without a large reduction in the current to the circuit embodying the switching device, whereas the latching current may be set at a low level to reduce the heat dissipation in the device just prior to the transition from the latching state to the holding state. The device, which may be implemented in either linear technology or with discrete components, is a thyristor structure defined by npn and pnp bipolar transistor devices each having its base connected to the collector of the other. Each transistor device has a resistance between its base and emitter, and in the case of at least one of the transistor devices that resistance varies with the voltage on the collector of the associated transistor device.