Power delivery

USB C is able to provide up to 20V @ 5A

CC pin is used for the “USB Power Delivery 2.0” single wire comms protocol.

This protocol allows for much more than just power negotiations, it unlocks the advanced capabilities of the USB Type-C cable.

PD messaging occurs completely independently of USB data and is used for port-to-port negotiation of power roles, voltage level, maximum supplying current capability, data roles, and Alternate Modes. Port-to-powered cable communication is also handled by USB PD.

Available Voltages

USB-C power supplies always support 5V. The provision of other voltages is optional and the most commonly are: 3.3V, 5V, 9V, 12V, 15V, 20V.

EPR adds 28V, 36V and 48V to the standard for up to 240W.

To get a voltage other than 5V you have to implement USB PD (Power Delivery) communication using the CC line. So if your device only wants 5V it is safe to assume a USB-C connection will always give it 5V regardless of its other voltage capabilities.

Comms spec

DFP is the Bus Master and initiates all communication.

300k Baud rate

All messages are 32-bit 4b/5b encoded Bi-phase mark coded (BMC).

CRC32 error detection + message retries

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