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Type-C Spec. Note(二)
Including: functional signal definition, discovery, and configuration process and PD;
According to the pin definition, Type-C signals includes :
USB 3.1 SS ; USB 2.0 D+/D-; CC channel; SBUs; GND ;VBUS; VCONN;
VBUS: USB CABLE BUS POWER. 当CC channel上的source与sink连接建立后，source才会提供VBUS power；
VCONN: 没有用作CC 通讯的CC pin，由Source提供，用来为PLUG供电；
SBU: 不需要连接，或<950K 下拉至GND；
The maximum allowable cable IR drop for ground (including ground on a captive cable) shall be 250 mV and for VBUS shall be 500 mV through the cable to the cable’s maximum rated VBUS current capacity. When VCONN is being sourced, the IR drop for the ground shall still be met considering any additional VCONN return current.
Type-C receptacle VBUS pin 只有在sink连接后才能提供power，当sink断开连接也要断开power。未连接sink时，要求如下：
VCONN may be removed under some circumstances as described in Table 4-3. VCONN may also be sourced by USB TypeC receptacles that do not utilize the SSTX and SSRX pins。
VCONN的电压特性如下表, 注意最小值可能为2.7V；
