Over-current protection circuit for voltage regulator
US4127885A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 21, 1977 |
| Grant date | Nov 28, 1978 |
| Priority date | — |
| Expiry date | Apr 21, 1997 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02H7/12
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A control transistor in the over-current protection circuitry of a voltage regulator is connected in a regenerative latch circuit with a complementary-conductivity auxiliary transistor, whereby conduction once initiated in said control transistor tends to be sustained. This avoids the tendency towards rapid oscillation between shut-down and power-up conditions in the over-current protection circuitry. The regenerative latch circuit loads the capacitor that supplies its sustaining current so heavily that the potential thereacross decays, the decay finally advancing to the point where regeneration halts. The resulting non-conduction of the control transistor permits the voltage regulator to attempt to resume the power-up condition. The present invention is an improvement in such a voltage regulator wherein circuitry is provided for rapidly recharging the capacitor for supplying sustaining current during this attempt. The recurrence of this cycle during short-circuit loading conditions leads to a relaxation oscillator mode of operation with the power-up duty cycle being sufficiently low that the components of the voltage regulator are kept from being damaged by overheating.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.