Boost controller capable of step-up ratio control
US7307385B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 18, 2005 |
| Grant date | Dec 11, 2007 |
| Priority date | — |
| Expiry date | Jul 11, 2025 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05B45/59
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A charge pump circuit boosts a voltage of a battery so as to generate a drive voltage for an LED. A constant current circuit generates a constant current to feed through the LED. A monitoring circuit monitors a cathode potential of the LED, i.e., a voltage across the constant current circuit. A control circuit receives a result of monitoring from the monitoring circuit 110 and increases a step-up ratio of the charge pump circuit when the voltage across the constant current circuit drops below a minimum voltage that guarantees a constant current. The control circuit sets an externally requested constant current value in the constant current circuit. When a change from a large current to a small current is requested, the control circuit returns the step-up ratio of the charge pump circuit to 1.0.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.