Charge pump drive circuit for a light emitting diode
US7271642B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 27, 2005 |
| Grant date | Sep 18, 2007 |
| Priority date | — |
| Expiry date | Feb 2, 2026 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02B20/30
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
Through operated alternately between a charging phase and a discharging phase, a charge pump converts an input voltage source into a drive voltage for being supplied to a light emitting diode. A current setting unit determines a reference current. A current regulating unit has a current regulating terminal and a feedback detecting terminal. The current regulating terminal is coupled to the light emitting diode so as to control a current flowing through the light emitting diode to be proportional to the reference current. The feedback detecting terminal provides a feedback signal representative of a current regulation characteristic voltage. Based on a difference between the feedback signal and a reference voltage source, an error amplifier generates an error signal. A variable resistance unit is coupled between the input voltage source and the charge pump for adjusting a variable resistance in response to the error signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.