Input protection circuit of a handheld electric device
US6816348B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 29, 2002 |
| Grant date | Nov 9, 2004 |
| Priority date | — |
| Expiry date | Oct 5, 2022 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02H11/006
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
An input protection circuit is provided for protecting internal circuitry of a handheld electric device. The internal circuitry has a positive input node and a ground node. The input protection circuit includes a power socket having a positive input node and a ground node, a bipolar junction transistor (BJT), a metal-oxide semiconductor (MOS) transistor for controlling the on and off states of the BJT, and an overvoltage protective circuit. An emitter of the BJT is electrically connected to the positive input node of the power socket, and a collector is electrically connected to the positive input node of the internal circuitry. When a reverse DC voltage or a DC voltage exceeding a threshold inputs from the power socket, the overvoltage protective circuit will turn off the MOS transistor, thereby turning off the BJT to prevent damages of the internal circuitry.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.