Patent · US Active

Adaptive switch mode LED driver

US8334662B2 · kind B2 · utility

39Cited by

6References

26Claims

0Family size

Assignee

iWatt Inc. · US

Inventors

Xuecheng Jin · Palo Alto, US
Yu-Cheng Chang · Taipei, TW
Yang Li · Santa Clara, US
Maofeng Lan · Palo Alto, US
John William Kesterson · Monterey, US
Xiaoyan Wang · Milpitas, US
Chenghung Pan · Palo Alto, US

Key dates

Filing date	Sep 11, 2009
Grant date	Dec 18, 2012
Priority date	—
Expiry date	Mar 2, 2031

Classification

Technology area (CPC Y)Emerging Cross-Sectional Technologies
CPC primaryY02B20/30
WIPO fieldElectrical machinery, apparatus, energy
WIPO sectorElectrical engineering

Abstract

An adaptive switch mode LED driver provides an intelligent approach to driving multiple strings of LEDs. The LED driver determines an optimal current level for each LED channel from a limited set of allowed currents. The LDO driver then determines a PWM duty cycle for driving the LEDs in each LED channel to provide precise brightness control over the LED channels. Beneficially, the LED driver minimizes the power dissipation in the LDO circuits driving each LED string, while also ensuring that the currents in each LED string are maintained within a limited range. A sample and hold LDO allows PWM control over extreme duty cycles with very fast dynamic response. Furthermore, fault protection circuitry ensures fault-free startup and operation of the LED driver.

Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.