What is it?

This is a breakout board for the FUSB302BMPX chip, which is a USB Type-C and USB Power Delivery controller. I've designed it to be as simple and unopinionated as possible, so it can be used in many applications.

Code

Watch this space :) working on my own library but it isn't ready for prime time yet. You can find plenty of existing examples out on the internet though.

How to use?

Description of each signal-

VBUS - USB power pin. Connected straight to the connector, no load switches involved- This is so you can bring your own switch- there are a lot of choices (nothing, single MOSFET, back to back MOSFET, load switch IC, a bidirectional DC/DC converter). The FUSB302B was designed for up to 20V operation, however I believe it may be possible to use it in EPR operation with some circuit modifications, but I've not tested this myself.

DSCHG - VBus discharge pin. USB Type-C and PD sources are "VBus cold"- Vbus should only be present when a sink is attached (as opposed to Type-A ports, which are Vbus hot). As such, it's helpful to have a circuit to actively discharge Vbus (as opposed to a passive bleed resistor, which may take too long and/or use too much power. The breakout features both). Specifically, the PD spec says Vbus must discharge to vSafe5v (5.5V max) within tSafe5V (275ms) and to vSafe0V (0.8V max) within tSafe0v (650ms max).

VDD - Power supply pin for the FUSB302B. Should range from 2.7V to 5.5V. Also used for the on-board I2C pullups, though these can be disabled by cutting a solder jumper on the back side of the board, if you wish to use your own logic level.

SDA/SCL - I2C interface. Up to 1Mhz (Fast Mode Plus) clock rate. Worth noting that PD timing requirements are strict enough that, depending on the speed of your MCU and/or firmware, 1MHz I2C can be useful to avoid problems, so check your config!

INT - Interrupt pin. FUSB302B pulls this low when it needs attention from the MCU.

VCONN - VConn source supply pin. Should range from 3.0V to 5.5V. FUSB302B can mux this supply onto the correct CC pin to power the eMarker in a cable's plug. Required by some, but not all source ports (see Section 4.4.3 of the Type-C spec)

CC1/CC2 - Configuration Channel pins, broken out for your probing pleasure :) It probably doesn't make sense to connect any external circuitry to these.

SBU1/SBU2 - Sideband Use pins. These are best known for their use in Alt Modes like DisplayPort, or Thunderbolt/USB4- but you probably aren't getting any of that done with this breakout's USB 2.0 only receptacle. They do still have some use though- Debug Accessory Mode is probably the most applicable.

D+/D- - USB 2.0 data pins. These are what they say on the tin :) USB Low Speed and Full Speed aren't too picky about signal integrity, but you should take care if you're hooking up a High Speed interface.

What's with those weird pads?

This breakout is designed for the FUSB302 as it comes in a hobbyist friendly QFN package. However, it is also available in a WLCSP form, and other pin compatible controllers exist (such as TUSB422, RT1711). Since these WLCSP packages require very advanced ($$$) PCB processes, the breakout is designed to accommodate these controllers using an interposer board. If you are especially interested in these controllers, get in touch :)