The SN74AVCH4T245-Q1 device uses two separate configurable power-supply rails, V_CCA and V_CCB. V_CCA accepts any supply voltage from 1.08V to 3.6V, and V_CCB accepts any supply voltage from 1.08V to 3.6V. The A port and B port are designed to track V_CCA and V_CCB respectively allowing for low voltage bidirectional translation between any of the 1.2-V, 1.5-V, 1.8-V, 2.5-V, and 3.3-V voltage nodes.

The output-enable (OE) input circuit is designed so that it is supplied by V_CCA, and all outputs are placed in the high-impedance state when the OE input is high. To put the outputs in the high-impedance state during power up or power down, the OE input pin must be tied to V_CCA through a pull-up resistor and must not be enabled until V_CCA and V_CCB are fully ramped and stable. The current-sinking capability of the driver determines the minimum value of the pull-up resistor to V_CCA.

V_CCA or V_CCB can be powered up first. If the SN74AVCH4T245-Q1 is powered up in a permanently enabled state, pull-up resistors are recommended at the input. This allows for proper or glitch-free power-up. For more information, refer to Designing with SN74LVCXT245 and SN74LVCHXT245 Family of Direction Controlled Voltage Translators/Level-Shifters application note.