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The SN74CB3T16212 is a high-speed TTL-compatible FET bus-exchange switch, with low ON-state resistance (r_on), 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 V_CC. The SN74CB3T16212 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 SN74CB3T16212 operates as a 24-bit bus switch or as a 12-bit bus exchange that provides data exchanging between four signal ports. The select (S0, S1, S2) inputs control the data path of the bus-exchange switch. When the bus-exchange switch is ON, the A port is connected to the B port, allowing bidirectional data flow between ports. When the bus-exchange switch is OFF, a high-impedance state exists between the A and B ports.

This device is fully specified for partial-power-down applications using I_off. The I_off 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, each select input should be tied to GND through a pulldown resistor; the minimum value of the resistor is determined by the current-sourcing capability of the driver.