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USB EZ-PD Type-C

New Contributor

I made a custom board consisting of a CYPD3125 controller.

The board shall be the preferred power supply to a tablet connected via USB type-c. In case the boards external supply is down the tablet shall power the board. So the board with the CYPD3125 must be either source or sink.

The firmware is based on the notebook project that has already all main functions.

Now the problem is that the producer FET is never turned on. I only measure ~150mV.

Does anyone have an idea?!

Please find the attached screenshot of the schematic.

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4 Replies
Moderator
Moderator

Hello,

The schematic looks fine. Please ensure that you are connecting to the tablet using a proper Type-C EMCA cable.

Could you please share the CC1, CC2, VBUS, VBUS_P_CTRL, VBUS_C_CTRL waveforms since the connection? Please also confirm that the firmware is default Host SDK firmware with changes only in the configuration such as source PDO fixed at 5V.

Please also attach the PD logs if any activity is seen.

 

Best Regards,
Sananya

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New Contributor

Hi Sananya,

thank you for your quick reply.

I do not use any cable. The board consists of a flexible part with type-c male connector that is directly plugged into the tablet. Does this cause any problems?

I use the default firmware. I just deleted/disabled the other PDOs except the 5V.

I have attached the screenshot of the osci. (Blue: CC1, Red: VBUS, Green: VBUS_C_CTRL, Yellow: VBUS_P_CTRL)

CC2 is exactly the same as CC1.

Best regards

Florian

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Moderator
Moderator

Hi Florian,

 

If you are using a male connector to connect to the tablet's Type-C receptacle, please ensure that only one CC pin is connected from CCG3 to the connector. This is because the EMCA cable would have provided a Ra termination on one of the pins so only the other CC pin would be used for the contract based on orientation. For your plug design, you could refer to the following schematic-https://www.cypress.com/documentation/reference-designs/ez-pd-ccg3-usb-type-c-charge-through-dongle

On the scope plots, I see VBUS going to 5V which isnt possible if the provider FET is turned off. Could you please confirm that the VBUS measurement is done at the Type-C connector i.e. after the FET?

Please also check if the 5V from supply is at the correct level before connecting to the tablet to ensure that the FET is not being turned off due to UVP fault. If possible, please provide the PD logs captured using the EZ-PD Analyzer utility or any other suitable analyzer.

 

Best Regards,
Sananya

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New Contributor

Hi Sananya,

right - i was able to solve this already by removing one CC Pin, but thank you for your reply.

There is one thing left:

I want to have priority on VBUS_P or better the producer path.

This means the producer path should be active as soon as VBUS_P is available. The DRP prefered role setting doesnt change here anything.

Best regards

Florian

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