DRV8256PEVM: DRV8256PEVM: Wrong ic? 0.5A “AIFS”?

Hi BB,

The device on the EVM should be correct. This by be an issue with the GUI. Have you tried measuring the current of the load? the device should be able to go higher than 0.5A FS. If not, please let me know.

Pablo Armet said:

The device on the EVM should be correct.

Should be, or IS correct? (“Should be” doesn’t sound very confident)  

Yes, I have measured the load. The motor driver runs fine under 0.5A but will not run above.

I have uninstalled and reinstalled the GUI software, but the issue persists. 

Thank you Pablo, I appreciate the help. 

Hi bb,

Can you measure the VREF voltage on the VM? What is the value?

VREF to GND  = 0.99VDC (this seems low...?)

VM to GND = 24VDC (this is what I am externally supplying) 

Hi bb,

There seems to be something wrong with the VREF voltage. It should be 3.3V.

Can you remove the resistor R23 and connect an external 3.3V supply on VREF. See if that allows you to drive the motor at higher currents.

I am not sure if we are trending in the right direction here.. 

R23 was removed. External 3.3V supply was applied on VREF.

Now the motor will not run at all (even under 0.5 amps), I have no voltage on the output pins, and the fault light is illuminated.

Hi BB,

I think this requires me to go to the lab and do the test myself with an EVM. Could be an issue with the EVM. Please give me about 24 hours to do the test. I'll respond back to you with my test results.

Thank you Pablo, I look forward to your results. 

Hi BB,

I was unable to go to the lab today to get do the test. I will go to the lab when I come back from holiday on 9/6

Hi BB,

I was not able to make it to the lab yesterday. Apologies for that.

We've received another similar post to yours regarding the wrong IC being populated on the DRV8256PEVM. We are currently investigating this to figure out if all boards have this problem. Looking more carefully at the images you attached, it looks like the IC populated is not the DRV8256P. The marking is of a pre-production part which was not removed from inventory when the final production part was released.

Please give us some more time to understand this problem and we will reach out to you soon

Thank you very much for the update, I look forward to your findings.

Would you be able to send me a DRV8256PEVM with the production ic so I can bench test it?

Hi BB,

Let me discuss this internally. I will get back to you soon.

Sounds like a plan. Thank you Pablo. 

BB,

Thank you for your patience.  I am working with Pablo on this.

Regards,

Ryan

Hi BB,

Just want to give you an update. I ordered a few EVMs from our warehouse and I will test them tomorrow. I will let you know my results.