USB Type-C DRP/DRD USB 2.0 without USB PD

The last USB 2.0 non-USB PD application available is the DRP/DRD. For non-USB PD applications, DRD and DRP are identical. A common example is a slower-speed laptop port that can send power in either direction – to charge or be charged, and act as either a host or a device. Another common application for this system type is tablets and smartphones. Figure 5 is an updated block diagram.

The only noticeable change from Figure 4 is adding the Rp/ Rd switch. A DRP/DRD can present itself as either a UFP or DFP. As a result, this design must have a method to pull the CC lines up with Rp or pull the lines down with Rd (default on a dead battery in order to charge), as shown in Figure 6. Notice how the switch can toggle between pulling the CC line up (in this case, with a current source to create a specific voltage across Rd), or pulling the CC line down to GND.

TI has a variety of devices that address DRP/DRD USB 2.0 without USB PD applications. These devices integrate the CC logic, Rp/Rd switch and – depending on the device – the VCONN switch.