Phoenix - ON Semiconductor says its NCP5008 and NCP5009 white-LED drivers are among the first to accommodate external phototransistor feedback to provide automatic adjustment of LED brightness according to ambient light.
The drivers for the white LEDs, which are used to backlight color liquid-crystal displays in portable electronics, are also among the first to include a serial data pin specifically for adjusting LED brightness with a microcontroller.
These dc/dc boost converters operate in a current-loop control mode. They deliver up to 15 volts from a 2.7- to 6-V input and thus can drive up to four white LEDs in series, or up to 10 in various parallel arrangements. In operation, they reduce the LED current as the ambient light increases.
Both devices are offered in the Micro-10 package (5 x 3 mm). The NCP5008 is priced at 72 cents each and the NCP-5009 at 80 cents, both in 10,000-piece quantities.
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