Need help choosing amp design for project


2013-02-22 7:21 pm
I have a project where I need to drive a piezo motor. This motor has 4 phases and uses a sin-like waveform on each phase at up to 3 kHz. I am driving this from a microcontoller, and can either drive from a PWM signal, or a 0-5V DAC. I need the output to be 0-48V at a max of 3 kHz. For those unfamiliar with piezo elements, you can just consider them to be a capacitor, these particular motors have a capacitance of 240 nF. This is driven in series with a 10 ohm 0.5W resistor. Each phase should not exceed 0.25W, but 0.5W capacity would be good.

I am currently using a standard audio opamp circuit to drive the motors, but this is a very inefficient design. I would like to move to a class D amplifier or something similar to drive the motors.

The motors have very long wires, so one of the downsides to class D amps that I have read about is getting a lot of RF noise on the output stage from the switching signal.

Any input on what type of circuit I should use, chips, etc would be appreciated.

John Vickers