In automotive and other lighting applications, it is often desirable to dim interior lighting. Using a mechanical potentiometer to perform this function would waste power, be relatively inefficient, and raise concerns about durability. In contrast, the design in this application note leverages user familiarity with up/down cellular phone controls, implementing an up/down light-dimming control that uses a low-cost digital potentiometer (digipot). Using a digipot not only avoids the inefficiency and mechanical durability concerns of a mechanical potentiometer; it actually conserves power and increases efficiency.