Other Parts Discussed in Thread: DRV2700,
Hello, I'm experimenting with the DRV2700EVM-HV500 evaluation board to understand if i can drive a piezolectric actuator with a DRV2700.
The actuator requires voltages up to 500V and the circuit seemed to be perfect. The actuator capacity is about 200nF.
The problem is that the high voltage output exibhits a huge amount of ripple (50Vpp with only about 20V setpoint!!!) with no load (with only the stock 1nF capacitor mounted on the PCB). If the capacitive load increases the ripple decreases, changes in frequency, but remains quite high. You can actually hear the noise from the piezoelectric element which vibrates at that frequency. Is this evaluation board broken in some way or it's a limitation of the flyback configuration of the DRV2700 ?
I run tests both with DC and arbitrary waveform output with the same results. I tried different types of capacitive loads, from 1nF to 300nF.
The ripple is higher at lower output voltages and lower capacitive loads.
Here the waveforms relatives to 10%, 50% and 90% duty cycle of input signal for 2nF and 200nF capacitive loads.
2nF, 10% duty-cycle input signal:
2nF, 50% duty-cycle input signal:
2nF, 90% duty-cycle input signal:
200nF, 10% duty-cycle input signal:
200nF, 50% duty-cycle input signal:
200nF, 90% duty-cycle input signal:
