The SN74CB3T3383 is a high-speed TTL-compatible FET bus-exchange switch with low ON-state resistance (ron), allowing for minimal propagation delay. The device fully supports mixed-mode signal operation on all data I/O ports by providing voltage translation that tracks VCC. The SN74CB3T3383 supports systems using 5-V TTL, 3.3-V LVTTL, and 2.5-V CMOS switching standards, as well as user-defined switching levels (see Figure 1).
The SN74CB3T3383 is organized as a 10-bit bus switch or as a 5-bit bus-exchange with enable (BE)\ input. When used as a 5-bit bus-exchange, the device provides data exchanging between four signal ports. When BE\ is low, the bus-exchange switch is ON, and the select input (BX) controls the data path. When BE\ is high, the bus-exchange switch is OFF, and a 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. The device has isolation during power off.
To ensure the high-impedance state during power up or power down, BE\ should be tied to VCC through a pullup resistor; the minimum value of the resistor is determined by the current-sinking capability of the driver.