SN74CB3T3257

• Output Voltage Translation Tracks V_CC
• Supports Mixed-Mode Signal Operation On All Data I/O Ports
  • 5-V Input Down To 3.3-V Output Level Shift With 3.3-V V_CC
  • 5-V/3.3-V Input Down To 2.5-V Output Level Shift With 2.5-V V_CC
• 5-V Tolerant I/Os With Device Powered-Up or Powered-Down
• Bidirectional Data Flow, With Near-Zero Propagation Delay
• Low ON-State Resistance (r_on) Characteristics (r_on = 5 Typical)
• Low Input/Output Capacitance Minimizes Loading (C_io(OFF) = 5 pF Typical)
• Data and Control Inputs Provide Undershoot Clamp Diodes
• Low Power Consumption (I_CC = 20 µA Max)
• V_CC Operating Range From 2.3 V to 3.6 V
• Data I/Os Support 0 to 5-V Signaling Levels (0.8-V, 1.2-V, 1.5-V, 1.8-V, 2.5-V, 3.3-V, 5-V)
• Control Inputs Can be Driven by TTL or 5-V/3.3-V CMOS Outputs
• I_off Supports Partial-Power-Down Mode Operation
• Latch-Up Performance Exceeds 250 mA Per JESD 17
• ESD Performance Tested Per JESD 22
  • 2000-V Human-Body Model (A114-B, Class II)
  • 1000-V Charged-Device Model (C101)
• Supports Digital Applications: Level Translation, USB Interface, Memory Interleaving, Bus Isolation
• Ideal for Low-Power Portable Equipment

The SN74CB3T3257 is a high-speed TTL-compatible FET multiplexer/demultiplexer 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 SN74CB3T3257 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 SN74CB3T3257 is a 4-bit 1-of-2 multiplexer/demultiplexer with a single output-enable (OE)\ input. The select (S) input controls the data path of the multiplexer/demultiplexer. When OE\ is low, the multiplexer/demultiplexer is enabled, and the A port is connected to the B port, allowing bidirectional data flow between ports. When OE\ is high, the multiplexer/demultiplexer is disabled, 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.