Method to protect gate-source elements of external power fETS from large pre-drive capacity
US5777502A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 7, 1996 |
| Grant date | Jul 7, 1998 |
| Priority date | — |
| Expiry date | Aug 7, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03K2217/0063
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A circuit (10) and method for protecting the gate-source elements of an FET includes a circuit (12, 13) for providing a pullup gate drive current to the gate-source elements. A voltage sensing circuit (45) senses a voltage on the gate-source elements to produce an indication if the voltage has exceeded a predetermined level. The voltage sensing circuit (45) has a zener diode (48) and a current mirror with first (52) and second (51) current flow paths. The zener diode (48) and the first flow path (52) are connected between the gate and a source of the FET. When a voltage between the gate and source of the FET exceeds the breakdown voltage of the zener diode (48) and one V.sub.gs in the current mirror, a current flows in the first flow path (52) producing a current flow in the second flow path (51). A circuit (20, 23, 62, 58, 60) reduces the pullup gate drive current in response to the current in the second flow path (51).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.