7.4 Device Functional Modes

The TPS25820/21 is a Type-C controller with integrated power switch that supports all Type-C functions in a downstream facing port (DFP). It is also used to manage current advertisement and protection to a connected sink and active cable. The device starts its operation by monitoring the IN bus. When IN exceeds the undervoltage lockout threshold, the device samples the EN pin. A high level on this pin enables the device and normal operation begins. Having successfully completed its start-up sequence, the device now actively monitors its CC1 and CC2 pins for attachment to a sink. When a sink is detected on either the CC1 or CC2 pin the internal MOSFET starts to turn-on after the required de-bounce time is met. The internal MOSFET starts conducting and allows current to flow from IN to OUT. For the TPS25820 if Ra is detected on the other CC pin (not connected to sink), VCONN is applied to allow current to flow from IN to the CC pin connected to Ra. For a complete listing of various device operational modes refer to Table 2.