The EVM has a built-in USB interface based upon the MSP432E401Y (U3) to allow the GUI, from the host computer, to communicate with the PMIC. The supply voltage required by the MSP432E401Y is generated automatically by the TLV7103318 (U6) device which provides 3.3 V and 1.8 V from USB power, VBUS. These voltages are available for supplying VIO_IN for the PMIC (selectable from J30). Two SN74GTL2003 level shifters (U8, U9) are used in order to support the use case of the PMIC VIO_IN of 1.8 V (the MCU IO will always be 3.3 V). It is important to note that the 3.3 V used for the MCU and the VIO_IN, MCUVCC, is different from the 3.3 V, 3V3V, provided to the PMIC through U13.

The TS3A5018RSVR switch is used to apply the pullup resistors for I2C communication with the MSP432E401Y. If the EVM is not a master (J37) or if SPI communication is used (J7, SPI_EN) then the pullups are not applied. The application of the pullup resistors is for I2C mode only and is only intended for one board in a stack-up application. Note: in the stack-up configuration only one board can have a valid VBUS voltage on the board. This means that the master board can have a connected USB cable supplying VBUS or that VSYS can be connected to VBUS through J15, see Table 3-6.

The EVM has 4 LEDs to indicate board power, on or off, and some select PMIC GPOs status. The signals are listed in Table 3-10.