The DC-coupled DAC input is used in applications when the user might need to drive the output at a constant DC level. A typical application for th the DC-coupled DAC input is for piezo pneumatic valves. A benefit to this application circuit is that all of the inputs, including power, are at a very low voltage while keeping the high-voltage piezo load separated. This feature allows easy implementation into systems and to help separate or isolate the high voltages loads from the critical controls.

Piezoelectric materials have a certain voltage that debias the piezo phenomenon. To prevent this debiasing from occurring, limit the input using a controlled input signal. As a backup measure, place a Zener diode to restrict the input.

Figure 8-13 DC-Coupled DAC Input