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USB-C Power Delivery Sink (CYPD3177)

wolfgangfriedrich

A USB-C PD Sink up to 20V 5A based on the Cypress CYPD3177 USB PD Controller

 

Edit: NEW Rev 4 now available. Important improvement with a 2nd switch to select the current! New FETs have a Rds_on of only 9.5 mOhm, which cuts the dissipation almost in half and keeps the board cooler, even with 5 A current draw.

 

 

USB-C PD offers the option to negotiate power delivery from a compatible power supply. This board plays the role of a sink device, enabling any device to be powered from a USB power supply. Any type of power connector can be attached through a 2-pin screw terminal or directly soldered into the PCB for a lower profile.

The voltage can be set to 5V, 9V, 12V, or 20V and  current can be set to 1A, 2A, 3A, or 5A.

BCR stands for Barrel Connector Replacement, the term is invented by Cypress, the manufacturer of the controller chip in use here.

 

Details

 

 

This board has the goal to replace random power adapters with a standardized way to use a USB-C power delivery (USB PD) adapter instead. For regular operation, no programming or software configuration is involved with this design. All options are set through the switches or resistor values. If needed an I2C interface to a microcontroller is available, to access status and control registers. This part of the board is separated through a break-off tab (mouse bites) and can be snapped off. I made the conscious design decision to not add a USB-A connector option at the output end. I did not want to build a device, that is capable of putting more than 5V on the VBUS pin of a regular USB cable and potentially destroy the device that is plugged in. A heatshrink tube can protect the board in a permanent installation.

 

This is a set and forget device. Set your current and voltage needs before plugging the device to your USB-PD source and enjoy the power at the output. This is not a power supply to change voltage and current during operation.

 

All Features:

  • USB-C PD Power Delivery Sink
  • Selector switch S1 for 5V, 9V, 12V, or 20V
  • Selector switch S2 for 1A, 2A, 3A, or 5A
  • Max current 5A, settable in 250mA steps through resistor options
  • Red LED to indicate failed power request
  • I2C telemetry interface to controller chip
  • Snap off option for telemetry interface
  • For fixed voltage, the switch can be replaced by wire jumper
  • Small form factor to be heat shrinked as part of the power cable
  • Size 53mm x 15.4mm (without telemetry interface)
  • Height 12mm with screw terminal and switch, 6mm without.
  • 3" (7.5cm) heatshrink tube for protected installation
  • 2oz copper to safely handle 5A
  • Lead free RoHS compliant

 

Design Information

 

New FETs with lower Rds_on (and another FET)

 

Selecting the right FET

 

Schematic attached below and available here:

 

https://hackaday.io/project/168762-usb-c-power-delivery-sink-bcr/files

 

 

 

Full disclosure

This board is for sale in my Tindie Store.

I sell on Tindie

 

Attachments:
SC USBC-Sink_ver4.pdfSC USBC-Sink_ver4.pdf
Anonymous
  • in reply to jancumps

    The caps on CC are a recommendation from Cypress in their reference design, the extra pull-up I found during my integration testing.

    And there are also an extra pull-up and zener diode between gate and source at the new FETs to protect them and not exceed the max gate-source voltage.

    The new FETs are for better temperature management. At 5A there is power dissipation of almost 0.5W per FET, which I wanted to spread between 2 packages. They still get very hot at 5As that some temperature management is recommended. 4A is the limit for still air operation. I found even better FETs with lower Rds-on but in an ugly package, a Rev 3 is probably coming in the near future.

    And I am way behind on documentation.

  • in reply to wolfgangfriedrich

      wrote:

    ...

    All is updated with rev 2 files now.

    New FETs, additional caps on the CC lines and an extra pull-up on the flip.

    What made you do these changes? Border cases where these components improved the design?

  • in reply to jancumps

    Thank you very much, this is very helpful. And I learnt something today, so I can go home now. Oh, I am home already, YAY for Heritage day in Canada.

  • in reply to wolfgangfriedrich

      wrote:

     

     

    And yes, this is a shameless self-plug, I hope somebody will find it useful and wanted to get it out there.

    When you edit a post (link in the right margin) , you'll find an "attach" link at the bottom of your post.

    Click it, and you can upload documents.

    Save after you've attached them (you can attach more than 1 doc).

  • in reply to jancumps

    That is good detective work. HaD.io is where this project started.

    All is updated with rev 2 files now.