High-Efficiency Step-Up Current Regulator for LEDs

 

Part Number	Replacement	Explanation

Description

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The MAX1698 and MAX1698A are efficient drivers for white or color LEDs. They are ideal for large LED backlit displays in PDAs and laptop computers. Numerous benefits include greater simplicity, lower cost, higher efficiency, longer bulb life, and greater reliability when compared to fluorescent (CCFL) and electroluminescent (EL) lamps.

The MAX1698/MAX1698A are switch-mode boost controllers in which LED current, rather than output voltage, is regulated The devices drive series-connected LEDs with a controlled current that is measured with a typically 15Ω sense resistor, not an expensive fractional-ohm value. LED current control and dimming are accomplished with an adjust input (ADJ). For larger light output, multiple LED banks can be connected in parallel with up to 5W total output power.

The MAX1698A has a higher, and more accurately specified, CS current limit than the MAX1698 for higherpower applications of 5W or more. Both devices are supplied in a space-saving 10-pin µMAX package that occupies half the space of an 8-pin SO. An evaluation kit (MAX1698EVKIT) is available to speed designs.

MAX1698, MAX1698A: Typical Operating Circuit Enlarge+

Key Features

• Over 90% Efficiency
• Lossless, Adjustable LED Brightness
• Space-Saving 10-Pin µMAX Package
• Simpler, Lower Cost, More Reliable Compared to CCFL or EL Backlights
• Up to 5W Output Power

Applications/Uses

• Backlight for LCD Panels
• Battery-Powered Backlight Applications
• Cell Phones
• Handy Terminals
• PDAs