Overcurrent sense circuit
US5559500A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 9, 1995 |
| Grant date | Sep 24, 1996 |
| Priority date | — |
| Expiry date | Mar 9, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R31/40
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An overcurrent is detected with small power consumption and at a high level of accuracy. A first transistor section 3 comprised of one NPN transistor 31 and a second transistor section 4 comprised of four NPN transistors 41-44 having the same characteristics as those of the transistor 31 are connected across a current sense resistor 2, with their emitters connected to the resistor 2. The transistors 31 and 41-44 have their bases commonly connected, with a voltage applied between their base and emitter by a voltage application unit 5, and have their collectors connected to transistors 61 and 62 which form a current mirror circuit. Once a bandgap voltage, .DELTA.V.sub.BE, i.e., a voltage difference between the base-emitter voltages of the transistor sections 3 and 4, is determined, the current density ratio of both the transistor sections 3 and 4 is determined, which is used to detect an overcurrent.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.