I'm looking for a replacement for other manufacturer's H-bridge motor driver. I found DRV8870 which I though might work in my application (I'm driving a speaker with a PWM signal). I hacked together a prototype and it works, kind of. With a 230 kHz 50% PWM input, I see some strange jitter at the outputs and this sounds like noise on the speaker. The delay from input going high to output going high varies from 700 ns to 800 ns (at least, I checked about 10 rising edges). I know 230 kHz is slightly higher than the recommended maximum PWM frequency of 200 kHz, but this shouldn't cause jitter at the outputs, I think.
VM=12 V, VREF=3.3 V, RSEN=0 ohm. Both outputs go through a 68 uH inductor to an 8 ohm speaker with capacitors to GND from both speaker terminals.
Is DRV8870 "sampling the inputs" at some internal frequency, causing the jitter I'm seeing? If it is, then I'll have to keep looking for a suitable H-bridge.. the noise I hear on the speaker is too loud to be acceptable.
