DRV8320: Internal connection from VM pin to VDRAIN pin

Hello Nagata-san,

Let go check internally first.

My guess is yes. This device isn't designed to be a true split supply operation like the DRV835x. Feel free to review the app note for more questions :  

This is because the charge pump is still generated from VM which eventually goes to the gate drive circuitry (which is also monitored by VDRAIN). This means, I'd think there's some internal protection to make sure they don't drift too far apart. 

Anyways, give me some time to go confirm internally.

Edit: We assume the DRV8320 is enabled during this time. Is that correct?

Best,

-Cole

Cole,

Thank you for your information. 

The document you shared shows "Figure 1. DRV835x Charge Pump Architecture". It connects to VDRAIN but it may VM in my case because power supply for VM and VDRAIN  are separated. Then, I guess this information doesn't explain the path between VM and VDRAIN internally.

Is there at path from VCP to VDRAIN pin via ESD diode internally?

Regards,
Nagata.

Hello Nagata,

Sorry for not being more detailed. That app note shows what a true split supply looks like. In the case of the DRV832x, VM is connected to the charge pump which means VM (the primary supply for the DRV832x) affects the reading on VDRAIN (the primary supply for the power stage), where a split supply would use VDRAIN to generate the VCP to keep the dependencies separate.

To answer your original question, there is some leakage between VSHx and VM which can be seen at the VDRAIN because of the VDS monitoring circuit. 

Best,

-Cole

Cole,

Is it acceptable to split power supply which use both power supply for VM and VDRAIN even if there is  the leakage from VCP to SHx?
I'm afraid if device may get damage. 

Regards,
Nagata.