DRV2700 EVM Output circuit as follows:
My set up as follows:
Test wavefrom as follows:(no load): CH2:OUT1 CH3: OUT2
my question:
The noise for output waveform causes the buzzer to produce a different sound during the on time.
Whether the output waveform can be modified by modifying the filter. The circuit as follows,Or there are other ways to solve.
Hey Hsu,
Are you controlling the DRV2700EVM with Piezo Control Console with your input signal coming from the PWM of the MSP430? Or do you have an external analog input? An external analog input bypasses the input filter on the EVM.
The input filter on the EVM is actually the filter shown in section 8.2.2 of the User Guide.
The current filter has an attenuation of about -22 dB at 2.5 kHz (by looking at figure 21). If you use the filter you suggest in figure 18, that still has an attenuation of around -18 dB at 2.5 kHz, so that will help but you could consider modifying the filter even more and have the corner frequency be closer to 2.5 kHz. Modifying the input filter will change the output waveform.
Hello,
If you change the two 3.3k resistors to 1k then the corner frequency will be closer to 3.3kHz. But after further consideration, the noise probably originates from the single ended output implementation rather than the input filter. If you use the differential output configuration as shown below in figure 14, then the output signal should be less noisy.
Hope that helps!
