MAXIM Integrated Products, represented in Australia by Arrow Electronics , has released the MAX8595/MAX8596 36V step-up dc-dc converters. They power up to eight LEDs in a series at 25mA.
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 noncompensated designs, users have to limit the LED current at room temperature. This requires more LEDs to get the desired brightness to a level low enough to ensure safety at higher temperatures.
1MHz current-mode PWM operation allows for a small inductor and output capacitor while minimising ripple on the input supply/battery. Efficiency is 86%. The input voltage range is 2.6V to 5.5V. While competitive products require two resistors and a capacitor to adjust brightness, the MAX8595/MAX8596 provide flexible dimming control with an analogue or digital PWM input without additional components. Other dc-dc converter features include internal soft-start to reduce in-rush current, low input ripple and a 0.3μA shutdown current to maximise battery life.
Both devices are available in 3mm x 3mm, eight-pin TDFN packages screened for -40ºC to +85ºC operation. The devices are pin-to-pin compatible with the MAX1561 and MAX1599.