Darlington connected switch having base drive with active turn-off
US4891532A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 8, 1988 |
| Grant date | Jan 2, 1990 |
| Priority date | — |
| Expiry date | Nov 8, 2008 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03K2217/0036
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A Darlington connected switching circuit (20) having a bipolar driver transistor (22) and at least one driven transistor (24) having a rapid and reliable turn-off characteristic with low losses suitable for use in power applications such as inverters. The collector to emitter potential of the at least one driven transistor is sensed by a comparator (26) to produce an output signal for controlling the conduction of minority carriers from the base of the driven transistor in response to sensing that the emitter to collector potential has become greater in magnitude than a reference potential (Vref) applied to the comparator. The reference potential is chosen to be at least a function of the switching characteristic of the driven transistor. Appropriate selection of the reference potential applied to the comparator insures that the driver transistor is sufficiently turned off to prevent false turn-offs under light load conditions while additionally ensuring that the at least one driven transistor is rapidly turned off after the driver transistor has been turned sufficiently off to prevent possible false turn-offs.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.