Keysight Type-C Connectivity Solution User Guide 41N7016A Type-C Low Speed Test Fixture 4Significance and Values of Rp, Rd, and Ra Termination Resistors in the USB Type-C Connector:A downstream facing port (DFP), such as a host computer, exposes pull-up terminations, Rp, on itsCC pins (CC1 and CC2). An upstream facing port (UFP), such as a peripheral, exposes pull-downterminations, Rd, on its CC pins. The purpose of Rp and Rd terminations on CC pins is to identify theDFP to UFP connection and the CC pin that will be used for communication. To do this, the DFPmonitors both CC pins for a voltage lower than its unterminated voltage.The N7016A low speed fixture has a fixed Rd value of 5.1 kΩ for the UFP connection and a fixed Rpvalue of 56 kΩ for the DFP connection. For simulating the VCONN connection, the Ra value is fixed at1 kΩ.The following table provides the values used for the DFP’s Rp based on the current sourcingcapability of the type-C port and the voltage that is connected to the Rp.The type-C cable needs to expose a pull-down termination, Ra, on its VCONN pin to signal to theDFP that it needs power. The DFP must be able to differentiate between the presence of Rd and Rato know whether there is a UFP attached and where to apply VCONN. The DFP is not required tosource VCONN unless Ra is detected.DFP Advertisement Resistor Pull-up to4.75 V - 5.5 VResistor Pull-up to3.3 V ± 5%Default USB power 56 kΩ ± 20% 36 kΩ ± 20%1.5A at 5 V 22 kΩ ± 5% 12 kΩ ± 5%3.0A at 5 V 10 kΩ ± 5% 4.7 kΩ ± 5%Minimum Impedance Maximum ImpedanceRa 800 Ω 1.2 kΩ
