AN-1053 Constant current LED driver with SPI control

This design is a Constant Current LED Driver with SPI control. LEDs are current-driven devices whose brightness is proportional to their forward current. Forward current can be controlled in two ways. The first method is using the LED voltage and current curve to determine what voltage needs to be applied to the LED to generate the desired forward current. The second, preferred method of regulating LED current is to drive the LED with a constant-current source. The constant-current source eliminates changes in current due to variations in forward voltage. Preferably, the input power supply regulates the voltage across a current-sense resistor. The power-supply reference voltage and the value of the current-sense resistor determine the LED current.


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