Output circuit having electronic overload protection activated by voltage drop across output transistor
US5896263A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 27, 1997 |
| Grant date | Apr 20, 1999 |
| Priority date | — |
| Expiry date | Jun 27, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03K17/0822
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
An output circuit has multi-stage protection circuitry for protecting against different fault current conditions. The protection circuitry operates by detecting voltage changes across the output transistor of the output circuit. The output circuit comprises first, second and third switching devices. The first switching device is connected to the output device and power conditions the output signal. The second and third switching devices override the output signal and turn off the first switching device when a magnitude of current through the first switching device exceeds predetermined magnitudes for predetermined amounts of time. A protection circuit is also disclosed which has a sensing device that senses a current flow condition by sensing a voltage drop produced across two terminals of the first power conditioning transistor, the two terminals being the terminals through which the current flows. Advantageously, the output circuit utilizes highly flexible two-stage protection circuitry. The protection circuitry separately identifies surge current and overcurrent conditions. In addition to the flexibility provided by the use of two-stage protection circuitry, flexibility is also …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.