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We are developing for a CCG3PA in a dual-role hub type product.
Currently, I am seeing about 100 – 300 ms power-down time on usb-c power when we switch between a tablet powering the bus vs the tablet being powered from the bus. I know that FRS is available on other CYPD chips, but not the CCG3PA. But, is there anything we can be doing to speed-up that turn around time? We are hoping to keep USB peripherals that are connected to the hub alive during the change in power direction. Thanks for any help.
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Hello Justin,
When the dock is powering the tablet and the power is removed from the dock then there will be a power shutdown which is expected, because the CCG3PA will put up a dead battery termination and then the PD contract is re-established.
But when the CCG3PA is powered externally when the power is being drawn from the tablet, the CCG3PA should initiate a PR_SWAP to the port partner to become a source. Do you see the same behavior on different devices. Please do let me know which firmware you are using for the CCG3PA chip.
Best Regards,
Yatheesh
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Hello,
Do you have the cc logs for this. If yes please do share it.
Can you please let me know which firmware you are using. Is it an example firmware or a custom one.
Best Regards,
Yatheesh
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Thanks Yatheesh. Below is a link to my EZ-PD Analyzer capture.
At 0 I plug a USB-C tablet into the powered dock. The tablet starts charging.
At 25 I un-power the dock with the tablet still plugged into the dock. At this point, the tablet starts powering the dock.
At 45 I re-power the dock. At this point, the tablet stops outputting power and then starts charging.
https://drive.google.com/open?id=124AdYcaSO5ndD851zsrldqUiXfctUPuA
When power is flipped, I see about a 100 - 300 ms down-time on the USB-C power bus. This causes any peripherals on the dock to re-enumerate, which is not desirable.
Thanks for any help!
Justin
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Hello Justin,
When the dock is powering the tablet and the power is removed from the dock then there will be a power shutdown which is expected, because the CCG3PA will put up a dead battery termination and then the PD contract is re-established.
But when the CCG3PA is powered externally when the power is being drawn from the tablet, the CCG3PA should initiate a PR_SWAP to the port partner to become a source. Do you see the same behavior on different devices. Please do let me know which firmware you are using for the CCG3PA chip.
Best Regards,
Yatheesh