The SN74CBT3345C is a high-speed TTL-compatible FET bus switch with low ON-state resistance (ron), allowing for minimal propagation delay. Active Undershoot-Protection Circuitry on the A and B ports of the SN74CBT3345C provides protection for undershoot up to 2 V by sensing an undershoot event and ensuring that the switch remains in the proper OFF state.
The SN74CBT3345C is organized as an 8-bit bus switch with two output-enable (OE, OE\) inputs. When OE is high or OE\ is low, the bus switch is ON, and the A port is connected to the B port, allowing bidirectional data flow between ports. When OE is low and OE\ is high, the bus switch is OFF and the high-impedance state exists between the A and B ports.
This device is fully specified for partial-power-down applications using Ioff. The Ioff feature ensures that damaging current will not backflow through the device when it is powered down.
To ensure the high-impedance state during power up or power down, OE\ should be tied to VCC through a pullup resistor and OE should be tied to GND through a pulldown resistor; the minimum value of the resistor is determined by the current-sinking/current-sourcing capability of the driver.