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Basically I want to add USB-C ports to my projects so I can use them to draw power.

From what I understand I need to put two 5.1 kOhm resistors between CC1/CC2 and ground. Would this allow the consumer device to pull up to 3A from the host, or would be limited?

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  • \$\begingroup\$ Are you making a USB-C provider, or device/consumer? \$\endgroup\$ Jun 5, 2019 at 21:17

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If you are making UFP (Upstream Facing Port), which means "consuming device", you need 5.1k pull-downs on both CC wires. The max current to take is determined by provider (host) capability, which is "advertised" by means of PULL-UPs on host/provider side. If the pull-up is 56k, no more than 500/900 mA can be taken by consumer. If PU=22k, then the load can be up to 1.5A. If the PU=10k, the port can source up to 3 A. It is a responsibility of device to measure the voltage on its pull-down resistors, determine the source capability, and restrict its consumption in accord.

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  • \$\begingroup\$ thanks man, you made it it clear to me. Essentially Rd are always 5.1k resistors and the consuming device needs to comply so that not to draw more that the advertised source capability :) \$\endgroup\$
    – TnF
    Jun 6, 2019 at 5:49
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    \$\begingroup\$ 56k indicates USB legacy power, which could be limited to 100mA from a bus powered hub, or over an amp from a USB Battery Charging Specification supply. \$\endgroup\$ Feb 26 at 8:35

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