To avoid potentially damaging current caused by floating CMOS input-only pins, TI recommends that unused ASIC input pins be tied through a pullup resistor to its associated power supply or a pulldown to ground unless specifically noted otherwise in Section 4. For ASIC inputs with internal pullup or pulldown resistors, it is unnecessary to add an external pullup or pulldown unless specifically recommended. Note that internal pullup and pulldown resistors are weak and must not be expected to drive the external line. When external pullup or pulldown resistors are needed for pins that have built-in weak pullups or pulldowns, use the value specified in Table 4-11.

Unused output-only pins must never be tied directly to power or ground, but can be left open.

When possible, TI recommends that unused bidirectional I/O pins be configured to their output state such that the pin can be left open. If this control is not available and the pins can become an input, then they must be pulled up (or pulled down) using an appropriate, dedicated resistor.