USB PD operation overview
Oct 04, 2019| USB PD operation overview
The side that supplies power to the USB PD port is SRC, and the one that receives power is SNK. Between ports, only one of each PD connection is SRC and one is SNK. The SRC terminal (providing a pull-up resistor) on the default connection is also DFP and VCONN SRC. The SNK terminal (with pull-down resistor) connected at the same time is also UFP, not VCONN SRC.
The modes of SRC/SNK, DFP/UFP, and VCONN SRC can all be converted by PD Message. The ports that support both SRC and SNK are called DRP, and the ports that support DFP and UFP are called DRD.
The following sections describe high-level work to assume the roles of DFP, UFP, SRC, and SNK. These sections do not describe the state of work that is not allowed; but if a particular behavior is not described, it is likely that it is not supported by this standard.
6.1 SRC Operation
The difference in SRC operating status depends on the connection status:
·
In the connected state (connection without PD)
·
1. For a port of SRC_Only, the SRC will detect if the SNK is connected.
2. For the DRP port, it will switch to become SRC to complete the connection with SNK.
3. Set VBUS to vSafe5V on the SRC side.
·
Before the PD connection (no PD connection or PD negotiation has not been established)
·
1. Before issuing SRC_CAP, the SRC can detect the type of Cable on the connection and then change its notification capability based on the type of Cable detected.
(1) The SRC will attempt to communicate with the Cable Plug using the SOP’ Message. If the Cable Plug responds, it starts communicating with it.
(2) The default USB Type-C cable supports 3A, but we can get the capability of this cable by sending a SOP’ Message.
2. The SRC periodically advertises its power supply capability by sending SRC_CAP to the peer within each tTypeCSendSourceCap time.
Shenzhen Shenchuang Hi-tech Electronics Co., Ltd(SChitec) is a high tech enterprise which specialized in phone accessories production and sales. Our main products include travel chargers, car chargers, USB cables, power banks and other digital products.All products are safe and reliable, with unique styles.products pass certificates like CE,FCC,ROHS,UL,PSE,C-Tick,etc, If you are interested in, you can contact ceo@schitec.com directly.
Stay Charging Safely with SChitec