DRV8353: SDO always output 0xff

Cherry Zhou

Part Number: DRV8353

Hi Team,

The customer use DRV8353RS in motor control system, trying to read from address 04h, but the output from MISO is always 0xffff, vbuck is OK, output signals also OK. They use 4 GPIOs to connect to DRV8353 SPI pins, trying to control DRV8353 by SPI interface, but SDO always output 0xff, could you please help to check is there any problem in schemetic and final signal?

For the first waveform, yellow is nSCS, blue is clock.
For the second waveform, yellow is clock and blue is MOSI
There is no need for the third waveform because MISO is always high.

Could you help check this case? Thanks.

Best Regards,

Cherry

over 2 years ago

0 Akshay Rajeev Menon over 2 years ago

TI__Mastermind 23536 points

Hey Cherry,

Is the device getting enabled well before you read the spi signals? Are you waiting for tWake before sampling?

Also I checked the register 4h

All the default values are 1 so maybe try writing a different setting with 0s in it to see if the devices is reading and writing properly.

Best,
Akshay

0 Cherry Zhou over 2 years ago in reply to Akshay Rajeev Menon

TI__Mastermind 22235 points

Hi Akshay,

Thank you for the support.

Yes, DRV8353RS is enabled, and the customer waited a long time (more than 10us) after system start and then keep on reading DRV8353RS register by spi. They also tried other registers, like 01h, 05h, but it still got all high output.

Thanks and regards,

Cherry

0 Akshay Rajeev Menon over 2 years ago in reply to Cherry Zhou

TI__Mastermind 23536 points

Hey Cherry,

Thanks for the update. The twake for this device is 1ms.

It seems like there might be some issue with the order in which the signals are being sent/read. I suggest consulting section 8.5 of the DS for SPI timings

Is the PVDD voltage stable during this event? Has the customer tested our EVM for this device, since that would be useful design and evaluation tool.

Best,
Akshay

0 Cherry Zhou over 2 years ago in reply to Akshay Rajeev Menon

TI__Mastermind 22235 points

Hi Akshay,

Twake is 10ms not 10us, sorry for the typo.

When the customer tested the third board, the SPI communication was successful. The first two boards were the brand new board and the drv8353 burned down board( which was replaced then). The first two boards may be hardware issues or the timing of the drive is critical which is unsure so they will dig into it.

Is there any suggestion for improvement on the above waveforms?

Thanks and regards,

Cherry

+1 Akshay Rajeev Menon over 2 years ago in reply to Cherry Zhou

TI__Mastermind 23536 points

Hey Cherry,

Thanks for the clarification. It is likely that the board damage could be a potential reason for the SPi issue seen.

What did the customer change in the third design to prevent he burn down observed in the first two boards?

Please check out the common debug FAQ on tips on MOSFET damage and overheating.

https://e2e.ti.com/support/motor-drivers-group/motor-drivers/f/motor-drivers-forum/1176539/faq-quick-guide-to-debugging-common-issues-in-bldc-motor-drivers

Please check out the following guide for tips on layout. This can help reduce ground noise seen in the waveforms.

https://www.ti.com/lit/an/slva959b/slva959b.pdf

Best,

Akshay

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DRV8353: SDO always output 0xff