Battery and current reversal protect circuit
US6628489B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | May 31, 2001 |
| Grant date | Sep 30, 2003 |
| Priority date | — |
| Expiry date | Jul 21, 2021 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02J7/0034
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A circuit and method are shown for battery reversal protection. The circuit includes a first transistor that buffers a bulk terminal of a protected transistor from an input terminal for receiving a power supply voltage. A second transistor is coupled to both the input terminal of the circuit and an output terminal of the circuit and detects when the power supply voltage falls below an output voltage at the output terminal and, responsive thereto, switches off the first transistor to isolate the bulk terminal of the protected transistor from the input terminal. Another aspect of the invention provides current reversal protection using a third transistor that also detects when the power supply voltage falls below an output voltage at the output terminal and, responsive thereto, conducts current from the output terminal to the gate terminal of the protected transistor. In yet another aspect of the invention, a bulk of the third transistor is coupled to a low current circuit to provide current to the low current circuit from the output terminal when power at the input terminal is interrupted. Because of low current demands on the transistors of the protection circuit, small area transi…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.