DRV8714-Q1: SDO

Ivy Jin

Part Number: DRV8714-Q1

Tool/software:

Hi team,

Could you please help review below customer's question and give some comments? Thanks!

The customer's SBC shares CLK, SDO, SDI signal lines with DRV8714S-Q1. The customer thinks that the SDO pin of DRV8714-Q1 will incorrectly pulls the SDO down when there is a no chip select signal, resulting in MCU and SBC communication anomaly, eventually resulting in SBC to constantly reset the MCU.

The customer has verified as follows, they removed the resistor between the SDO pin of the DRV8714-Q1and the shared SDO wire, replaced it with a switch that is set to closed;

Waveform 1： the SDO pin of DRV8714-Q1 will incorrectly pulls the SDO down when there is a no chip select signal, resulting in MCU and SBC communication anomaly.

Waveform 2： Switch off, shared SDO line signal OK, SBC no longer resets the MCU, and the MCU can send the message normally.

Thank you!

Regards,

Ivy

8 months ago

0 Keerthivasan Kumanan 8 months ago

TI__Genius 15685 points

Hi Ivy,

Does this occur on all the boards. Can they desolder the resistors to all the SPI lines and jump in SPI lines from another MCU or the EVM and then monitor the SPI lines.

Best,

Keerthi

0 Ivy Jin 8 months ago in reply to Keerthivasan Kumanan

TI__Expert 3835 points

Hi Keerthi,

This problem does not occur on all boards. At present, the customer found that the 3pcs board will replicate this problem, and the problem is sporadic, not every time. The customer has done A-B-A exchange validation and the issue follows these three 8714 chips.

Regards,

Ivy

0 Ivy Jin 8 months ago in reply to Keerthivasan Kumanan

TI__Expert 3835 points

Hi Keerthi,

Could you please help review their schematic and check if they have any design issues? Thanks!

Regards,

Ivy

0 Keerthivasan Kumanan 8 months ago in reply to Ivy Jin

TI__Genius 15685 points

Hi Ivy,

Can they solder down the bad IC onto an EVM and see if they can replicate the issue on the EVM. Just trying to rule out any board dependencies.

Best,

Keerthi

0 Murugavel4637 8 months ago in reply to Keerthivasan Kumanan

TI__Mastermind 35465 points

Hi Ivy,

While the customer is checking the suspect IC with an EVM, could you please confirm the following? DRV8714 has specified DVDD and in active mode while this test was done. Why is the chip select signals in the both the scope shots are showing digital noise?

Regards, Murugavel

0 Ivy Jin 8 months ago in reply to Keerthivasan Kumanan

TI__Expert 3835 points

Hi Keerthi,

I will let the customer to do the EVM test then feedback to you.

Regard,

Ivy

0 Ivy Jin 8 months ago in reply to Keerthivasan Kumanan

TI__Expert 3835 points

Hi Keerthi,

Because the DRV8714-Q1 on the EVM board is 56pin VQFN(RVJ) package, but the chip that customer used is 40pin VQFN(RHA) package, so they can't check the IC issue based on the EVM. Do you have any other way to verify the possibility of this problem? Thanks.

Regards,

Ivy

0 Keerthivasan Kumanan 8 months ago in reply to Ivy Jin

TI__Genius 15685 points

Hi Ivy,

Can you check the following suggestions from Murugavel:

DRV8714 has specified DVDD and in active mode while this test was done. Why is the chip select signals in the both the scope shots are showing digital noise?

As well as can you remove the connection to the SBC and then check the SPI lines to DRV to see if it still occurs.

Best,

Keerthi

0 Ivy Jin 8 months ago in reply to Keerthivasan Kumanan

TI__Expert 3835 points

Hi Keerthi，

OK, I will let the customer to do the related tests.

Thanks.

Regards,

Ivy

0 Keerthivasan Kumanan 8 months ago in reply to Ivy Jin

TI__Genius 15685 points

Hi Ivy,

I will wait for update.

Best,

Keerthi

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DRV8714-Q1: SDO