3.3-V Low-Voltage Quadruple FET Bus Switch With 5-V Tolerant Level Shifter

The SN74CB3T3125 is a high-speed TTL-compatible FET bus 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 SN74CB3T3125 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 SN74CB3T3125 is organized as four 1-bit Bus Switches with separate output-enable (1OE, 2OE, 3OE, 4OE) inputs. It CAN be used as four 1-bit Bus Switches or as one 4-bit bus Switch When OE is low, the associated 1-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 1-bit 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 circuitry disables the outputs, preventing damaging current 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; the minimum value of the resistor is determ c7d ined by the current-sinking capability of the driver.
By Texas Instruments