LED driver with fast open circuit protection, short circuit compensation, and rapid brightness control response
US7550934B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 2, 2008 |
| Grant date | Jun 23, 2009 |
| Priority date | — |
| Expiry date | Apr 2, 2028 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02B20/30
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
An LED driver drives one or more strings of series-connected LEDs. A feedback voltage at a sense resistor is detected by an op amp, and the op amp controls the conductivity of a MOSFET in series with the LEDs to regulate the peak current. The MOSFET is also controlled by a PWM brightness control signal to turn the LEDs on and off at the PWM duty cycle. A boost regulator provides an output voltage to the string of LEDs. A divided voltage at the end of the string of LEDs is regulated by the boost controller to keep the divided voltage constant. When an LED becomes an open circuit, the boost regulator controller is immediately decoupled from the regulator's switching transistor. If an LED shorts, the boost regulator reduces its output voltage, and the duty cycle of the brightness control signal is automatically increased.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.