3.4.2.2 USBB Host Interface

The USBB port can act as a USB device or USB host interface and can be accessed via the USB Type-C connector (J8).

Two resistors (R192 and R193) are placed on its power rail to form a voltage divider, converting 5V into 3.3V voltage that is then used to indicate the presence of a USB host to the MPU (USBB_VBUSDETECT_PC12).

Figure 3-35. USB-B Port Schematic
Table 3-25. USB-B J8 Connector Signal Descriptions
Signal Description Signal Name Pad Name Pin No. Pin No. Pad Name Signal Name Signal Description
Ground GND GND A1 B1 GND GND Ground
Not used Not connected TX1+ A2 B2 TX2+ Not connected Not used
Not used Not connected TX1- A3 B3 TX2- Not connected Not used
Port-B 5V power USBB_VBUS_5V VBUS A4 B4 VBUS USBB_VBUS_5V Port-B 5V power
Sideband use USBB_CC1 CC1 A5 B5 CC2 USBB_CC2 Configuration channel
Port-B data plus USBB_P D+ A6 B6 D+ USBB_P Port-B data plus
Port-B data minus USBB_N D- A7 B7 D- USBB_N Port-B data minus
Not used SBU1 SBU1 A8 B8 SBU2 SBU2 Not used
Port-B 5V power USBB_VBUS_5V VBUS A9 B9 VBUS USBB_VBUS_5V Port-B 5V power
Not used Not connected RX2- A10 B10 RX1- Not connected Not used
Not used Not connected RX2+ A11 B11 RX1+ Not connected Not used
Ground GND GND A12 B12 GND GND Ground
Table 3-26. USB-B PIO Signal Description
PIO Signal Name Shared Signal Description
PC12 USBB_VBUSDETECT_PC12 – VBUS detection

In Host mode, the USB Host port B is equipped with 500-mA high-side power switches to enable self-powered and bus-powered applications. The USBB_EN_5V_PC11 signal controls the current limiting power switch MIC2025, which in turn supplies power to a client device. As per the USB specification, bus-powered USB 2.0 devices are limited to a maximum of 500 mA, therefore the MIC2025 limits the current and indicates an overcurrent with the USBB_OVCUR_PC22 signal.

Figure 3-36. USB-B Port Power Switch Schematic
Table 3-27. USB-B Power Switch PIO Signal Descriptions
PIO Signal Name Shared Signal Description
PC11 USBB_EN_5V_PC11 – Power switch enable (active high)
PC22 USBB_OVCUR_PC22 – Indicates overcurrent (open drain)