TPS65987EVM: No communication on CC lines

Martin Neumaier

Part Number: TPS65987EVM

We us a TPS65987 in GPIO mode to control a TUSB1046. If I connect a USB Stick to my design everything is working as expected, but there is no communication on the CC lines. If I connect the same stick to the TPS65987EVM there is a lot of communication on the CC lines.

Our main problem is, that the DP-Alt Mode is not detected. My CC analyzer only detects "Hard_Reset", if I connect a DP-Alt Mode device.

The schematic is more or less a copy of the TPS65987EVM and the TUSB1146EVM. It was checked by TI but I could send it to you as privat message

Thanks

over 4 years ago

0 Hari Patel1 over 4 years ago

TI__Genius 12700 points

Hi Martin,

How do you have your CC lines connected? Also, could you verify your PD is getting VIN_3V3?

For the DP-Alt Mode, I would also recommend checking the DisplayPort Alt Mode App Note and making sure the process described there is being followed.

Thank you,

Hari

0 Martin Neumaier over 4 years ago in reply to Hari Patel1

Prodigy 220 points

Hi Hari

The CC Lines are connected directly to the connector, just some protection diodes (TI TPD1E01B04). The detection of a USB device works, but only over Ra/Rd, FLIP works too, so I can confirm that the PD is getting VIN_3V3. I can also connect the Application Customization Tool over I2C2

Schematic of TPS65987 and connector below

0 Hari Patel1 over 4 years ago in reply to Martin Neumaier

TI__Genius 12700 points

Hi Martin,

I don't see any capacitors on the CC pins, I would recommend adding 220pF both CC pins. Also, are you only using this application to source 5V only and no sinking capabilities?

Is there a reason you did not connect VBUS1 and VBUS2 together?

I will look further into the schematic and provide additional feedback later this week.

Thank you,

Hari

+1 Martin Neumaier over 4 years ago in reply to Hari Patel1

Prodigy 220 points

We found it, VBUS1 and VBUS2 have to be connected

Thank

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TPS65987EVM: No communication on CC lines