The 3-state control gate is a 2-input AND gate with Active-Low inputs so that if either Output Enable (OE1 or OE2) input is HIGH, all nine affected outputs are in the high-impedance state. To ensure the high-impedance state during power up or power down, OE should be tied to Vcc through a pull-up resistor; the minimum value of the resistor is determined by the current-sinking capability of the driver.