SPI voltage level translation

Question: Why two different SPI connection schemes are presented in the WirelessUSB datasheet?

 

Answer:

The reason for the different SPI hardware interfacing connection schemes in the WirelessUSB datasheet is that in tranmit-only battery powered device block diagram both devices are powered from the same 3V source and in the USB bridge transceiver block diagram the enCoRe device is powered from the USB connector (VBus ~5V source) and the WirelessUSB device is powered from 3V source (via LDO).