Power Electronics

Step-up DC-DC LED Drivers

Maxim Integrated Products’ new MAX8595/MAX8596 are 36-V step-up dc-dc converters that power up to eight LEDs in a series at 25 mA. The MAX8596 automatically adjusts its output current based on the ambient temperature so that it delivers the maximum recommended LED current (based on the derating curves of popular white LEDs) at all temperatures.

In non-compensated designs, users have to limit the LED current at room temperature—and therefore use more LEDs to get the desired brightness—to a level low enough to ensure safety at higher temperatures. With the MAX8596, the LED current reduces automatically at higher temperatures. Consequently, the user can safely run higher currents at room temperature and use up to 33% fewer LEDs, saving cost and space.

Fast 1-MHz, current-mode PWM operation allows for a small inductor and output capacitor while minimizing ripple on the input supply/battery. Efficiency is a high 86%. The input voltage range is 2.6 V to 5.5 V. While competitive products require two resistors and a capacitor to adjust brightness, the MAX8595/MAX8596 provide flexible dimming control with an analog or digital PWM input without additional components. Both devices are available in space-saving 3-mm × 3-mm, 8-pin TDFN packages screened for the –40°C to +85×C temperature range.

For more information, visit www.maxim-ic.com.

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