A single bit is used, and its output is restricted to two values (true of any single bit). Varying voltage values are represented by varying the time the bit is turned on (pulsed), using Pulse Width Modulation (PWM). A longer pulse represents a larger current value in the analog waveform, and a shorter pulse represents a smaller current value. In this way, the entire audio signal can be represented, using a single bit.

The obvious benefit is the elimination of the "zero cross error" that plagues multi-bit designs. Of course, there's a down side, too. 1-bit DACs require very fast clock speeds, which can be difficult to achieve. And they tend to be noisy compared to multi-bit designs. One solution to the 1-bit noise problem is the Delta Sigma design, where the 1-bit DAC's output is modulated to a much higher frequency than is actually needed in the end, and then the output of that process is averaged over time, obtaining high accuracy through the long-term average of a sequence of single bits. The result is a DAC that avoids both the zero cross error of multi-bit designs, and the noise problems of other 1-bit DACs.