http://uphotos.eepw.com.cn/soothmusic/pics/03660905292735246c4839a728d83912.jpg

摘要：该电路从3.3V电源并联驱动多达四个白光LED ，并调整总LED电流从1mA到106毫安在64个步骤，每一个为1dB 。

Maxim/Dallas > App Notes > AUTOMOTIVE DIGITAL POTENTIOMETERS DISPLAY DRIVERS

Keywords: portable power, white LEDs, logarithmic dimming, charge pump, digital potentiometer Jul 20, 2004

APPLICATION NOTE 3287
White-LED Driver Provides 64-Step Logarithmic Dimming

This circuit drives as many as four white LEDs in parallel from a 3.3V source, and adjusts the total LED current
from 1mA to 106mA, in 64 steps of 1dB each.


The circuit of Figure 1 is designed for portable-power applications that require white LEDs with adjustable,
logarithmic dimming levels. It drives as many as four white LEDs from a 3.3V source, and adjusts the total LED
current from 1mA to 106mA in 64 steps of 1dB each. The driver is a charge pump that mirrors the current ISET
(sourced from U3's SET terminal)