Piezoelectric actuators offer many benefits over traditional solenoid counterparts. Piezoelectric actuators are more precise, power efficient, and smaller in general when compared to solenoid actuators. One challenge with piezoelectric actuators is that the piezoelectric actuators operate over a very wide voltage range. Driving voltages of more than 60V are not uncommon, and can easily reach hundreds of volts. The OPAx596 operate with a supply voltage of up to 85V.

In this design example, the OPAx596 are used to provide a 100V_PP signal to control a high-voltage piezoelectric actuator (see also Figure 7-1). The piezoelectric actuator can be modeled as a large capacitor when operated at less than the resonant frequency. The piezoelectric actuator is treated as a floating load driven by two op amps of the OPAx596. The outputs of the op amps are set to be 180° out-of-phase to essentially double the voltage seen by the actuator load.

The signal voltage of the digital-to-analog converter is applied a 10V/V gain by the OPAx596. A simple voltage divider provides a 2.5V reference to level shift the output to create a unipolar driving voltage. An isolation resistor improves phase margin and stability. Add a small 10Ω R_ISO at the output of the OPAx596.