TUSB321AI: Test board of TUSB321AI does not work

Colin Cook1

Part Number: TUSB321AI
Other Parts Discussed in Thread: TUSB321

Tool/software:

In thread TUSB321AI: TUSB321 configurations. I asked several question about the operation of the TUSB321AI. Thinking I understood everything, I built a small test board to verify.

This test board has a TUSB321AI and a single USB-C connector. Configured in DRP (Dual Roll mode)
I connected the boards with a USB-C cable. And powered one of them.

I expected the the one with power to configure as a DFP, and assert ID low. And the other board to configure as an UFP. I also expected that as I pulled the the cable and flipped it, that the DIR pin would change.

Nothing happens, DIR never changes, ID never changes. It's like the chip is not even there.

What did I do wrong?

I tired powering both boards, nothing at all. One of them should have asserted ID, and DIR should change as a flip the cable.

5 months ago

0 Vishesh Pithadiya 5 months ago

TI__Mastermind 38090 points

Hi Colin,

On thing I notice is that the PUP on the ID may be too strong at 4.7k. Try using a 200k here. The issue may be that ID cannot be not pulled low.

0 Colin Cook1 5 months ago in reply to Vishesh Pithadiya

Prodigy 100 points

I changed the ID resistor on both boards. No change. Neither one asserts ID.

0 Vishesh Pithadiya 5 months ago in reply to Colin Cook1

TI__Mastermind 38090 points

Hi Colin,

When no USB device is connected to the system do you see the CC1 and CC2 pins toggle? They should cycle between 0v and 5v in an 50-100us interval.

Are you able to capture this waveform?

0 Colin Cook1 5 months ago in reply to Vishesh Pithadiya

Prodigy 100 points

Yes, I do see CC1 and CC2 toggle with no cable attached. However, as soon as I attached the cable, CC1 and CC2 went to ground. I expected something in between.

I was examining the soldering of the part, and I can not be 100% sure all pads are making good contact, so I have sent the boards back to my CM for xray and reflow. That will take a bit.

Please do not close the ticket until I have more data.

0 Vishesh Pithadiya 5 months ago in reply to Colin Cook1

TI__Mastermind 38090 points

Hi Colin,
Sounds good. Let me know when you have more info regarding the soldering connections.

0 Vishesh Pithadiya 5 months ago in reply to Vishesh Pithadiya

TI__Mastermind 38090 points

any update?

0 Colin Cook1 5 months ago in reply to Vishesh Pithadiya

Prodigy 100 points

Just got back in town, hope to have repaired boards back from CM on Monday

0 Colin Cook1 5 months ago in reply to Colin Cook1

Prodigy 100 points

I got 2 reworked board, the ID did assert and DIR seemed to be changing based on flipping the cable. the low voltage was not that low however, I think I need to use even higher resistance on the DIR pullup.
This worked for all of 2 minutes until I noticed the bench PSU current shot up and the PCB got really hot. Now nothing works.
So back to square one to figure out what happened.
In the working case, I only powered one board, and it tuned on a power FET to feed power to the second board. When I powered both boards is when things went south. It should not have done that. And I don't know why yet. If you have any ideas, please let me know.

0 Vishesh Pithadiya 5 months ago in reply to Colin Cook1

TI__Mastermind 38090 points

Hi Colin,

At least we have the CC pins detecting a connection before things went south.

Colin Cook1 said:
the low voltage was not that low however, I think I need to use even higher resistance on the DIR pullup.

what was the low voltage seen here?

What was the PSU powering, are you able to test with a TUSB321 EVM?

Colin Cook1 said:
When I powered both boards is when things went south. It should not have done that. And I don't know why yet. If you have any ideas, please let me know.

How were both boards connected? What was the Vbus path between these boards?

0 Colin Cook1 5 months ago in reply to Vishesh Pithadiya

Prodigy 100 points

Pulled low DIR was still at 1V Changing pullup to 10K.

Both boards are identical and the full schematic is above. Externally, a USB-C cable connected them, and my bench support powered both.

Got 2 new boards and they seem to be functioning as expected. I still need to do more testing, connect some random devices and make sure they do not fry.

0 Colin Cook1 5 months ago in reply to Colin Cook1

Prodigy 100 points

Connected to power brick and was able to supply power to second board, attached a USB-C downstream device, and it received power. I do believe this is working enough as expected I can move on to a real project. Thanks.

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TUSB321AI: Test board of TUSB321AI does not work