Forum Post: RE: question on DRV2605 PWM Input?

Nancy,

Thanks for evaluating the DRV2605!

Yes, the PWM input mode on the EVM is closed loop, because we assumed if you use an LRA that would want to use closed loop operation.  That means we useautomatic resonance tracking all the time which is why the frequency does not change when you change the input.

The open-loop mode is not directly available on the EVM, but can be enabled by changing the settings inside the DRV2605 IC.  There is a bit in the register map that sets open and closed loop operation for LRAs.  If you are in open loop, then the input frequency should be 128 x the output frequency. 

Thanks,
Brian