Switch circuit having excess-current detection function
US6011416A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Nov 19, 1997 |
| Grant date | Jan 4, 2000 |
| Priority date | — |
| Expiry date | Nov 19, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02H3/0935
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A microcomputer 4 responds to an instruction signal to turn the load L on or off to control the FET 2 through the drive circuit 5. The microcomputer 4 samples an electric current I.sub.L which is supplied through the A/D converter 6 and which flows in the load L at every predetermined sampling time T.sub.S and subjects the sampled electric current I.sub.L to a comparison with a known rated current value I.sub.R for the load L. When I.sub.L .gtoreq.I.sub.R is satisfied, the microcomputer 4 starts counting energizing time T. When the accumulated value of I.sub.L .times.T.sub.S is enlarged to a predetermined value S.sub.O, the microcomputer 4 turns the FET 2 off. When the detected electric current I.sub.L is larger than an upper limit I.sub.O (>I.sub.R) determined previously, the microcomputer 4 immediately turns the FET 2 off through the drive circuit 5.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.