The CEDRAT TECHNOLOGIES SA75A is a high-frequency PWM switching amplifier purpose-designed for driving piezoelectric actuators — capacitive loads that present unique challenges to conventional linear amplifiers. Using a topology optimized for capacitive impedance, the SA75A recovers energy stored in the piezo element during discharge cycles, reducing total power consumption by up to a factor of 10 compared to equivalent linear amplifiers.

What operating modes does SA75A support?

In open-loop (Servo Off) mode, the amplifier applies a fixed voltage gain of 20 to the input signal — a -1V to +7.5V control input produces a -20V to +150V output. In closed-loop (Servo On) mode, the SA75A works with CEDRAT's SG75 strain gauge conditioner or ECS75 eddy current sensor conditioner and UC45/UC65 digital servo controllers to provide position or force feedback control of the piezo actuator. The BNC input connector (50Ω impedance) accepts standard function generator or DAQ card signals.

How does the protection system handle fault conditions?

Three independent protection circuits guard the amplifier and actuator: output voltage clamps at +170V/-30V prevent overvoltage damage to the piezo element; output current limiting at ±25A peak handles momentary capacitive inrush without nuisance tripping; and thermal protection shuts down if amplifier or actuator temperature reaches 80°C. All fault conditions latch — recovery requires an intentional OFF-ON sequence on the A7 switch, preventing automatic restart into a persistent fault. Short-circuit protection covers both load-side and transistor-side faults.