SCES693G February 2008 – May 2021 SN74AVC4T774
The SN74AVC4T774 device uses two separate configurable power-supply rails, VCCA and VCCB. VCCA accepts any supply voltage from 1.1 V to 3.6 V and VCCB accepts any supply voltage from 1.1 V to 3.6 V. The A port and B port are designed to track VCCA and VCCB respectively allowing for low-voltage, bi-directional 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 VCCA and when the OE input is high, all outputs are placed in the high-impedance state. To ensure the high-impedance state of the outputs during power-up or power-down, the OE input pin must be tied to VCCA through a pullup resistor and must not be enabled until VCCA and VCCB are fully ramped and stable. The minimum value of the pullup resistor to VCCA is determined by the current-sinking capability of the driver.