Shutdown circuit and battery pack using same
US5574358A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 12, 1994 |
| Grant date | Nov 12, 1996 |
| Priority date | — |
| Expiry date | Dec 12, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG05F1/465
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
A current limited linear regulator including a pass transistor 56 is provided with a shutdown circuit 64 comprised of a shutdown transistor 90, base resistor 92, and zener diode 98. When a excessive load is placed on the regulator and the current level limit is reached, the output voltage begins to drop and the voltage drop V2 across the pass transistor 56 increases. When the voltage drop V2 across the pass transistor 56 is equivalent to the sum of the zener voltage of the zener diode 98 and the emitter-base junction bias voltage of the shutdown transistor 90, the transistor 90 switches a current into bias resistor 62 that prevents the control circuit from regulating the output, causing the pass transistor to become highly resistive and shut off. The shutdown circuit holds this condition until the offending load is effectively removed. The zener diode is chosen according to the power rating of the pass transistor 56 and the predetermined current level limit.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.