Introduction
The USB-C Sink board is a USB-C to XT30 adapter designed to deliver up to 100W (20V 5A) of power to a drone during stationary debugging and testing.
For more on design decisions, see the engineering documentation at USB-C Sink.
Core Functions
This device was built to function in auto-run mode, meaning that the end user can simply connect the USB-C port to a source and have a power to a load connected through the XT30. The board uses the USB-PD (Power Delivery) protocol to arbitrate its voltage and current with the source device.
NOTE: There are multiple board variants that arbitrate different voltage values. Check the silkscreen at the back of the board to view which voltage has been configured (circled with a marker).
The 20V and 12V boards are configured with a minimum of 3A and maximum of 5A current. This means that your source (wall power adapter) needs to be able to deliver the voltage circled on the silkscreen and a minimum of 3A current. This information is likely visible in fine print on the adapter.
LEDs
To summarize the LED notes in the schematic:
When the Green LED is ON, the sink device is functioning and delivering power to the load.
When the Red LED is ON, the sink device has failed to negotiate a USB PD contract with the PD-compatible source device. This mean the source device may be unable to fulfill the voltage and/or current requirements of the USB-C Sink. This LED will not turn on when the source is not designed for USB-PD.
When the Blue LED is ON, the USB-C connector has been flipped (and is therefore using the CC2 pin for arbitration). This is does not affect the functionality of the device.
I2C Test Points
The TPS25730 can provide debug and diagnostic information through the interface. NOTE: The arbitrated voltage of the device is NOT configurable over I2C.
There is a chance that the pull-up resistors for the bus have not been placed during assembly (DNPed). Please verify that they have been soldered before attempting to use the I2C bus.
Schematic
Resources