8.3.5 Pullup Resistors on I/O Lines

Each A-port I/O has an internal 10-kΩ pullup resistor to V_CCA, and each B-port I/O has an internal 10-kΩ pullup resistor to V_CCB. If a smaller value of pullup resistor is required, an external resistor must be added from the I/O to V_CCA or V_CCB (in parallel with the internal 10-kΩ resistors). Adding lower value pullup resistors will effect V_OL levels, however. The internal pullups of the TCA9406 are disabled when the OE pin is low.