DRV8880: IC non operational/damaged while varying the Vref

Sreenath Chatterjee

Part Number: DRV8880
Other Parts Discussed in Thread: STRIKE

Hello Team,

We have been working on the operation of this IC for the purpose of driving a stepper motor(NEMA 17). We also wanted to make sure that we are varying the Vref of the driver using a potentiometer rated at 10K.
While testing and varying the potentiometer the stepper motor was working fine for about 10 Sec and then we were never able to operate the motor. We even tried varying the Pot but it was only showing same resistance(0.637 Ohm) in whatever wiper position.

After changing to a new IC the driver started working and is running at evey varying resistance. But when we tried soldering back the old IC it didn't work. As per the datasheet the IC has internal Overcurrent / Thermal Shutdown / Undervoltage, in this case the IC should disable itself and resume when in normal condition. But straight away the IC got damaged even with this protections.

If possible we would like to know the possible causes for this type of senario.

Testing Parameters -

Vref - 10K pot with 3.3V
VCC - 12V
Thermal Pad - 2 Layers GND + Heatsink

Thanks & Regards,
Sreenath C.

over 2 years ago

0 Ryan Kehr over 2 years ago

TI__Guru 55605 points

Sreenath,

It appears to me that somehow the VREF pin was damaged. This can occur with an ESD event. Where you wearing wrist strap and following proper ESD bench practices while varying the resistance of the potentiometer?

Even with on-chip protections, the device can't handle a direct ESD strike on pins. The internal protections are more on the output side of the device to protect main driver FETs.

Regards,

Ryan

0 Sreenath Chatterjee over 2 years ago in reply to Ryan Kehr

Prodigy 10 points

Hi Ryan,

For the following operation we used a regular screwdriver with minus head that matched the size of the POT. Also because the screwdriver was rubber-insulated, it appears that the ESD would not be passing to the POT or the Vref Pin.
Hope you got my point.

Regards,
Sreenath C.

0 Ryan Kehr over 2 years ago in reply to Sreenath Chatterjee

TI__Guru 55605 points

Sreenath,

Sounds like you did everything right including wearing a wrist strap. Somehow the device was damaged and I don't know what else could have caused it.

Is the new device working well?

Regards,

Ryan

0 Sreenath Chatterjee over 2 years ago in reply to Ryan Kehr

Prodigy 10 points

Hey Ryan,

Yes it's been somewhile and the new device is working without any flaw.

Regards,

Sreenath C.

0 Ryan Kehr over 2 years ago in reply to Sreenath Chatterjee

TI__Guru 55605 points

Sreenath,

Let me know if any further issues arise.

Regards,

Ryan

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DRV8880: IC non operational/damaged while varying the Vref