DRV8245-Q1: Does the digital interface requires any protection?

Vel Murugan

Part Number: DRV8245-Q1

Hi All,

We designed a board using DRV8245HQRXZRQ1 (Hardware Variant) and connected both SPI lines and hardware PWM control lines to the MCU.
Occassionally we see the MCU got damaged or 3.3V power circuitry got damaged.
We suspect that that SPI & other hardware PWM lines may require an isolation, but we are not very sure.

Note: Functionality-wise we don't see any issue at the moment, but random failure raise a concern to us. We have observed around 5 board failures out of 20 boards tested so far

So, like to confirm whether any isolation circuit required to be added between MCU and this driver IC operating with +24V poer supply.
Attached the schematic and if any review feedback, we are welcoming..

Regards,
Vel Murugan

over 1 year ago

0 Shinya Morita over 1 year ago

TI__Mastermind 44895 points

Hi,

Thank you for your questions. Let me reply to you within 24hours.

regards

Shinya Morita

0 Shinya Morita over 1 year ago in reply to Shinya Morita

TI__Mastermind 44895 points

Hi ,

Thank you for your questions. Could you provide your customer's name and application use case(e.g door handle, Mirror folding etc)

Pins you are connecting to MCU's SPI is MODE/ITRIP/SR/DIAG. Those pins provide voltage/sourcing current to external resisters to measure the external resister value.

This action happens right after nSLEEP 20-40us pulse inserted.

Your MCU could be damaged by this activity.

And DRVOFF pin has internal pull up to VDD(5V).

I have attached my schematic review.

regards

Shinya Morita

240521_DRV8245Q1_schematic_review.pptx

0 Vel Murugan over 1 year ago in reply to Shinya Morita

Prodigy 30 points

Hi Shinya Morita,

Thanks a lot for your review comments. It helped us to understand the possile root cause of the issue.

DRVOFF pin has internal pull up to VDD(5V), but our MCU is operating with 3.3V, so the IO line connecting to DRVOFF pin is 3.3V. How should I drive the DRVOFF pin from the 3.3V MCU?. Do i need to use a MOSFET as like open-drain by connecting its drain pin to DRVOFF, gate pin to MCU IO and source pin to GND?.

Does operating the remaining IO from the 3.3V has any issues?

0 Vel Murugan over 1 year ago in reply to Vel Murugan

Prodigy 30 points

Further on datasheet, i see that DRVOFF pin has an internal pullup to VDD but reverse current blocked. What does it mean?
i am assuming the device ha an internal pull up but it is isolated, so it shouldn't impact the 3.3V MCU IO connected to DRVOFF pin. Please check with the design team and clarify..