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I was wondering about a minimal device (sink) design with USB C connector. In this case, where the device will only accept 5V and not further, I think a USB C controller is not mandatory. But I dont know how to terminate the CC1 and CC2 lines in order for the host (power provider) to know that the only available pdo level is 5V/2A. I have found this source but its not straight forward to me: https://www.silabs.com/community/mcu/8-bit/knowledge-base.entry.html/2016/09/26/what_s_the_role_ofc-kQYe

I would appreciate all help.

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  • \$\begingroup\$ Does this link help? \$\endgroup\$ – Finbarr Aug 13 at 16:35
  • \$\begingroup\$ Not quite. While I get the CC connection part (and I assume is the same for other cc line), then I dont know to where is the second part connected on the connector (with Ra resistor). Besides, this table provides information on how can the device check the host capabilities. I kind of need the way around. \$\endgroup\$ – Bremen Aug 13 at 20:07
  • \$\begingroup\$ That's not how USB works. The host/source/downstream facing port says what it's capable of providing and the device/sink/upstream port chooses what it wants from what's available. If it only wants 5V it just doesn't ask for anything higher. \$\endgroup\$ – Finbarr Aug 14 at 7:41
  • \$\begingroup\$ @Finbarr thanks for answer. This seems ok, as a device I can ask for anything. But the thing is i still dont know what capacity 5V charger was connected (or a PC). \$\endgroup\$ – Bremen Aug 14 at 13:55
  • \$\begingroup\$ Yes, you do - the value of pullup resistor Rp tells you. By measuring the voltage on your pulldown resistor Rd you can determine the DFP's capability. \$\endgroup\$ – Finbarr Aug 15 at 14:06

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