Feb 23 2008
Catalyst Semiconductor, Inc. a supplier of analog, mixed-signal and non-volatile memory semiconductors, announced it has received a patent for a unique step-down switching regulator circuit architecture applicable to step-down regulators for driving high brightness LEDs. The patent, titled "LED current bias control using step-down regulator" (patent number 7,323,828), was developed to simplify the design of high brightness LED lighting in emerging household, commercial and automotive lighting applications.
The patent is embedded in the Company's new line of inductor-based, step-down LED drivers, which bridge the gap between the two traditional choices for LED driver design: simple-to-use, but power-hungry linear regulators; and switching regulators, which offer lower power dissipation, but are more complex and difficult to implement. The new patent enables a simpler, smaller, more cost-effective and far more power-efficient "green" LED driver alternative to linear regulators.
"When using this new step-down switching scheme, the designer simply selects a control resistor and the patented switching regulation scheme provides an inherently stable and accurate LED bias across a wide range of voltage operating environments without the complicated equations or calculations associated with alternative LED switching regulators," stated Anthony Russell, Catalyst's Power Management Director and co-inventor of the patent.
Traditional switching regulators operate in both Continuous Conduction Mode (CCM) and Discontinuous Conduction Mode (DCM), making them intrinsically complex. Catalyst's patented step-down switching regulator architecture operates at the precise intersection between CCM and DCM, the point Catalyst calls Crossover Conduction Mode (XCM), to offer a simpler and more power-efficient solution. Catalyst's XCM architecture enables efficient operation over a wide range of high voltage system supplies, versus linear regulators which operate efficiently over a very small supply voltage range. Additionally, the XCM operation offers unconditional stability and eliminates the need for high-power current sense resistors and associated interface pins, reducing size, complexity and cost.
The first product to incorporate Catalyst's step-down switching regulator architecture is its CAT4201, a high-efficiency 7W buck LED driver optimized for driving high-brightness, 350mA LEDs at up to 94 percent efficiency.