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The SN74CB3T16211 is a high-speed TTL-compatible FET bus 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 SN74CB3T16211 supports systems using 5-V TTL, 3.3-V LVTTL, and 2.5-V CMOS switching standards, as well as user-defined switching levels.

The I/O port of this device has a pullup current source that maintains the output voltage at V_CC when the device is ON, and the input is greater than or equal to V_CC – 1. Because of the pullup current source, the output voltage level may be less than V_CC when the operating frequency is low and the I/O port is connected to a pulldown resistor. In order to maintain the output voltage at V_CC, a pullup resistor must be connected to V_CC instead of a pulldown resistor to ground.

The SN74CB3T16211 is organized as two 12-bit bus switches with separate output-enable (1OE, 2OE) inputs. It can be used as two 12-bit bus switches or as one 24-bit bus switch. When OE is low, the associated 12-bit bus switch is ON, and the A port is connected to the B port, allowing bidirectional data flow between ports. When OE is high, the associated 12-bit bus 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 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, OE should be tied to V_CC through a pullup resistor; the minimum value of the resistor is determined by the current-sinking capability of the driver.