Digital Potentiometer that doesn't step?

Aaron Wall

I have a specific idea that requires a good way of controlling the brightness of a led with the ability to instantly adjust to the desired brightness.

Right now I have an AD5220 controlling a NPN transistor that controls the ground side of the led. It works, but requires steps in the form of pulses, so it has to be stepped to the desired resistance. This process takes too long, the potentiometer can fall behind if the rate of change needed exceeds how fast the potentiometer can be steeped. What I need is a chip that can change to the desired resistance by receiving a serial signal, such as a value up to 256, and goes right to that setting.

Does anyone have a good solution to this problem?
Or another approach that would achieve the same goal?

Thanks,

-Aaron

dev/null

One option is to use a shift register (or several of them daisychained) like 74HC595 with different resistors connected to the outputs. This would allow you to step to whatever resistor value you wanted. You need the same amount of pins (three) for this solution, and the 74HC595 is really cheap.

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