DRV8662: Abnormal waveform of DRV8662 with Load

Dear Sirs，

Do you know what's the problem with the DRV8662?

DRV8662‘s output is normal on condition of no piezo load,but output abnormal with piezo load

Attached are the waveform with and no piezo load!

SCH is same to the DRV8662EVM schematic

piezo load is 3.7uF

Gain1=Gain2=0

Please help.

Thanks.

Cherry Zhou：

Hi,

We've got the issue and escalated to e2e for more help as the link below, you could take a look at it:

https://e2e.ti.com/support/motor-drivers-group/motor-drivers/f/motor-drivers-forum/1123057/drv8662-abnormal-waveform-of-drv8662-with-load

,

Cherry Zhou：

Hi,

How does the boost voltage/PVDD look in this case? is the PVDD stable, or is it collapsing?

Our thought is that perhaps the boost cannot supply the necessary current. If that is the case you can try a few things, 

-decrease Rext,

-use larger boost inductor, 

-use larger capacitor at output of the boost

,

sandy.shixy Shi：

Hi cherry

I will check the boost voltage and try your advices right now

Thanks