Question
Do I need an external pull up resistor on the SDO pin if the Busy Indicator
feature is not required?
Answer
No. An external pull up resistor is only required if the Busy Indicator feature
is used. When the Busy Indicator feature is used the SDO pin goes from
three-state to active low at the EOC point. To ensure this change can be
detected by the input to a controller the pull up resistor ensures the
three-state condition is seen as a high level at the controller.