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USB EZ-PD Type-C

nyoung
New Contributor

We have an issue in one of our designs where the CYPD3125 is not communicating with any host device. We had it working at one point with the power negotiation functioning as expected with CY4531 evaluation kit. After one good power up the CY4531 evaluation kit no longer functioned as expected. It will not power up our device or other off the shelf USBC products we verified work with other supplies. Even the USB flash demo will no longer work on the CY4531. Since then we have tried using a separate USBC power supply device. We have verified this supply works with other, off the shelf USBC devices. But our board will not power on.

All we see with the packet analyzer when attaching our board is the source sending out SOURCE_CAP messages. Our board's CCG3 never seems to respond to these. It also will inconsistently draw the current limit of the supply, 3A. Every few packets in the CY4500 analyzer output shows -3A on VBUS and no current otherwise.

We tried reworking the board to replace the CYPD3125 and still see the issue. We also tried plugging the board in while there was no CCG3 device on it and did not see any current draw with the analyzer, so we don't think there is a short on the board itself (unless there is a reason for the analyzer readout to not function with one side of the connection not having a CCG3). The firmware we are using was functional when the power negotiation worked once so we don't think that is a cause of failure. Plus the firmware does work on our other designs.

Any insight or support to help track down the problem would be greatly appreciated.

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1 Solution
PranavaYN
Moderator
Moderator

Hi,

This seems to be some hardware issue and probably after the VBUS FETs. Therefore you are not able to detect the issue when you remove CCG3. Please try out the following and let me know the results.

1. With CCG3 connected please measure voltage of VDDD, VCCD, VSYS and VDDIO pins.

2. If possible please replace the CCG3 on your board to a CY4531 board and program its default firmware and check if the IC works fine. This will help us isolate the issue either the board or the FW/ CCG3 internal configuration.

3. Do let me know if you are able to reprogram the CCG3 on the board.

Best regards,
Pranava

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2 Replies
PranavaYN
Moderator
Moderator

Hi,

This seems to be some hardware issue and probably after the VBUS FETs. Therefore you are not able to detect the issue when you remove CCG3. Please try out the following and let me know the results.

1. With CCG3 connected please measure voltage of VDDD, VCCD, VSYS and VDDIO pins.

2. If possible please replace the CCG3 on your board to a CY4531 board and program its default firmware and check if the IC works fine. This will help us isolate the issue either the board or the FW/ CCG3 internal configuration.

3. Do let me know if you are able to reprogram the CCG3 on the board.

Best regards,
Pranava

View solution in original post

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nyoung
New Contributor

The excessive draw is definitely after the FETs. I removed them and though CCG3 still didn't respond the excessive current went away. So our board is shorting somewhere unrelated to the Cypress chip. Additionally, while checking those four pins I realized we were missing a jumper to tie VDDD and VDDIO together. After I placed it the CCG3 began responding and negotiating power as expected. So our CCG3 issue has been resolved. Thanks

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