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 DescriptionSignal NamePad NamePin No.Pin No.Pad NameSignal NameSignal Description
GroundGNDGNDA1B1GNDGNDGround
Not usedNot connectedTX1+A2B2TX2+Not connectedNot used
Not usedNot connectedTX1-A3B3TX2-Not connectedNot used
Port-B 5V powerUSBB_VBUS_5VVBUSA4B4VBUSUSBB_VBUS_5VPort-B 5V power
Sideband useUSBB_CC1CC1A5B5CC2USBB_CC2Configuration channel
Port-B data plusUSBB_PD+A6B6D+USBB_PPort-B data plus
Port-B data minusUSBB_ND-A7B7D-USBB_NPort-B data minus
Not usedSBU1SBU1A8B8SBU2SBU2Not used
Port-B 5V powerUSBB_VBUS_5VVBUSA9B9VBUSUSBB_VBUS_5VPort-B 5V power
Not usedNot connectedRX2-A10B10RX1-Not connectedNot used
Not usedNot connectedRX2+A11B11RX1+Not connectedNot used
GroundGNDGNDA12B12GNDGNDGround
Table 3-26. USB-B PIO Signal Description
PIOSignal NameSharedSignal Description
PC12USBB_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
PIOSignal NameSharedSignal Description
PC11USBB_EN_5V_PC11–Power switch enable (active high)
PC22USBB_OVCUR_PC22–Indicates overcurrent (open drain)