Products, Materials & Tools | Aug 29, 2007

High-Power, High-Efficiency HB LED Driver with Rapid Current Pulsing Is the First to Drive Common-Anode LEDs

Maxim Integrated Products (NASDAQ: MXIM) introduces the MAX16821 high-power, synchronous high-brightness LED (HB LED) driver that has rapid current pulsing and is the first to drive common-anode LEDs. Its patent-pending, rapid-current-pulsing LED technology meets the demanding requirements of projection applications, thus making it ideal for front-projection, rear-projection TV (RPTV), and pocket-projector applications that require very fast LED dimming capabilities.

Additionally, the unique, innovative driver architecture of the MAX16821 allows HB LEDs to be mounted in the common-anode configuration, a necessary requirement for truly efficient thermal management that reduces system integration and assembly costs.

Key features: 
• Up to 30A Output Current
• True-Differential Remote Output Sensing
• Average Current-Mode Control
• 4.75V to 5.5V or 7V to 28V Input-Voltage Range
• 0.1V/0.03V LED Current-Sense Options Maximize Efficiency (MAX16821B/MAX16821C)
• Thermal Shutdown
• Nonlatching Output Overvoltage Protection
• Low-Side Buck Mode with or without Synchronous Rectification
• High-Side Buck and Low-Side Boost Mode with or without Synchronous Rectification
• 125kHz to 1.5MHz Programmable/Synchronizable Switching Frequency
• Integrated 4A Gate Drivers
• Clock Output for 180° Out-of-Phase Operation for Second Driver
• -40°C to +125°C Operating Temperature Range

The MAX16821 also features a unique pin configuration capability that allows the device to be operated in either synchronous buck or synchronous boost mode. Synchronous buck and synchronous boost modes allow the LED driver to operate at very high efficiencies, a performance requirement that is particularly important in high-power applications such as automotive exterior lighting and emergency lighting systems.

The wide switching frequency range (125kHz to 1.5MHz) allows small inductors and filter capacitors to be used in applications such as pocket projectors where system designers are faced with extremely tight space constraints. For systems requiring multiple drivers, the MAX16821 also features a clock output with 180° phase delay that can control a second, out-of-phase LED driver. This feature can be used to minimize LED current ripple, thereby reducing the size and cost of the input and output filter capacitors even further.

The highly integrated MAX16821 operates from 5.4V to 28V with an LED current-sense voltage of 0.03V, providing the lowest dissipation of power. (Other current-sense voltage versions are also available.) Additional features include programmable hiccup, overvoltage protection, reverse current limit, and an output-enable function. The MAX16821 operates over the automotive temperature range of -40°C to +125°C and is available in a tiny, lead-free, 5mm x 5mm x 0.8mm, 28-pin TQFN package with an exposed pad. Prices start at $1.82 (1000-up, FOB USA). For additional informatio visit .

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