greenpowerZONE Products for the week of January 1, 2007
Maxim Integrated Products Says....
High-Efficiency, High-Power, Fast-Transient-Response LED Driver Controller is Tailored for Projection and Lighting Applications
Maxim Integrated Products introduced the MAX16818 high-efficiency LED-driver controller for projection and lighting applications, that utilize the next-generation of high-power light-emitting diodes (LEDs). The MAX16818 is the first LED-driver controller that enables Maxim's patent-pending technology for rapid LED-current transients of up to 20A/µs and 30kHz dimming frequency.
The MAX16818 pulse-width-modulation (PWM) controller provides high-output-current capability in a compact, lead-free package with a minimum number of external components. Average current-mode control, synchronous gate-drive circuitry, and a wide switching-frequency range make this device ideal for the energy-efficient driving of high-power LEDs in light sources for business, portable, and pocket projectors; home theater systems; rear-projection TVs; and automotive and industrial lighting fixtures.
The MAX16818 is suitable for use in synchronous and nonsynchronous step-down (buck) topologies, as well as in boost, buck-boost, SEPIC, and Cuk LED drivers. This device employs average-current-mode control, which optimizes the charge and on-resistance characteristics of MOSFETs, thus minimizing the need for external heat sinking, even when delivering LED current up to 30A. Its flexibility and small footprint make 5W to 200W driver designs possible with the industry's highest efficiency (up to 94%). True differential sensing enables accurate control of the LED current. A wide dimming range is easily implemented to accommodate an external PWM signal. An internal regulator enables operation over a wide input-voltage range of 4.75V to 5.5V, 7V to 28V, or higher with a simple external biasing device. The wide switching-frequency range available (up to 1.5MHz) allows for the use of small inductors and capacitors.
The MAX16818 features a clock output with 180° phase delay to control a second out-of-phase LED driver, which reduces the required size of the input and output filter capacitors and minimizes ripple currents. This device also offers programmable hiccup-mode overcurrent, overvoltage, and overtemperature protection.
EN-Genius Says...
Intended primarily for high-powered automotive lighting and putting watt-hungry video projectors on diets, the MAX16818 should also help make LED-based commercial and industrial area lighting much more practical and cost-effective. The driver/controller goes beyond the basics and offers several clever features including a very flexible PWM dimming scheme and second 180° phase delayed clock output to control a second out-of-phase LED driver that, depending on your design priorities, can help reduce input and output filter capacitors size or minimize ripple currents.
 By integrating all the bias and current control circuitry required to run up to 200 W worth of drive power plus all the necessary protection circuitry, Maxim has kept the cost of drive electronics in step with the steadily-declining cost (and steadily-improving quality) of HBLEDs while adding several innovative features. In doing so, they have taken a major step towards putting HBLEDs on an even footing with fluorescent tubes -- at least in applications where light quality, longevity and the ability to dim are important.
Of course many solid-state lighting applications will be replacements for incandescent bulbs which will require direct operation from a 120 Vac line, something that this device cannot do. But even if it does not immediately revolutionize lighting, it will certainly tame the heat and power problems of projection TVs and data projectors. I recently stumbled onto Toshiba's 1-lb, battery-powered TDP-FF1AU, data LED-based projector at the Digital Life show and it looks like the future to me. Even if the power savings (more than 80%) were not a consideration, the 10 k-hour lamp lifetime and small form factor that the solid-state light source makes possible tells me that we'll start seeing lots more LEDs in projectors and projection TVs. And I expect many of those HBLED arrays will also have a MAX16818 driving them.
The MAX16818 is available in both extended and automotive temperature ranges in Pb-free thermally-enhanced TQFN-28 with pricing starting at $1.59 in 1000-piece lots.
Data Sheet
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