DRV2700: DRV2700 gets hot and die! Schematic and Layout is like the EVAL board

Maximilian Pohl said:

Part Number: DRV2700

Hello,

i have a big problem with my DRV2700 piezo driver circuit. Some are working fine and some are not.

Even complete new assembled pcbs have this problem.

Connect the DRV2700 to 5V without enable pin high, everything is as expected. But as soon in set the enable pin high,  the DRV2700 gets very fast very hot.
I only have 15V on the output (should be 100V)

I tried lower Vout settings with the same result. I have almost the same layout as the one on the eval board.

Any known issue with the DRV2700 or any other ideas? i am struggling here.

Thank you, best regards

Max

Hi, Maximilian,

Do you have same results when you remove the components from the output? I mean, if you leave the OUT+ and OUT- outputs floated, do you have the same behavior?

Best regards,
Luis Fernando Rodríguez S.

Hi Luis,

yes i tested it. It is the same. (tested it on both new and old one).
The chip kills itself in the first second i enable it.

best regards

Max

Hi, Max,

Thank you for your response.

Could you try with another test? Could you try adding to the analog inputs some AC-coupling capacitors like C16 and C19 of the EVM schematic:

https://www.ti.com/lit/ug/slou403c/slou403c.pdf#page=25

As far as I understand, the boost converter requires of these capacitors in order to achieve the common-mode voltage. In addition, could you try leaving the analog inputs floated as well (no signal through these AC-coupling capacitors)?

Best regards,
Luis Fernando Rodríguez S.

Hi Luis,

thank you for your fast support.

I removed R8,R11,R11 and C8 to let the analog inputs floating.

I am not shure that AC-coupling caps will work for me. i want to use the DRV2700 with a DC signal (DAC output)

Now i have 10V on the output but 0,7Amps from the 5V supply.

Best regards

Max

Hi Luis,

i just noticed that i have connected the Pin 9 (NC) to GND.
Because this is shown in the datasheet (Layout Example Section).
But on the Eval -Schematic this pin is floating, could this be an issue? But why is it in the datasheet?

I think it is the same issue like you already disscused a few month ago:

Best regards

Max

Hi, Max,

This could be definitely an issue. Did you have better results if you remove the NC pin from GND?

Best regards,
Luis Fernando Rodríguez S.

Hi, Max,

Excuse me, do you have a feedback on this? Did you get better results if you remove the NC pin from GND?

Best regards,
Luis Fernando Rodríguez S. 

Hi Luis,

thanks for your help. I didnt had time yet to test it. Hopefully tomorrow i will test it.
I will inform you about the result.

Best regards

Max

Hi, Max,

Please let us know if you have additional details on this. We will be glad to provide additional support.

Best regards,
Luis Fernando Rodríguez S.