1 Features

1• Output Voltage Translation Tracks VCC

• 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 VCC

– 5-V/3.3-V Input Down to 2.5-V Output-Level

Shift With 2.5-V VCC

• 5-V-Tolerant I/Os With Device Powered Up or

Powered Down

• Bidirectional Data Flow, With Near-Zero

Propagation Delay

• Low ON-State Resistance (ron) Characteristics

(ron = 5 Ω Typical)

• Low Input/Output Capacitance Minimizes Loading

(Cio(OFF) = 4.5 pF Typical)

• Data and Control Inputs Provide Undershoot

Clamp Diodes

• Low Power Consumption (ICC = 20 μA Max)

• VCC 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

• Ioff 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)

2 Applications

• Supports Digital Applications: Level Translation,

USB Interface, Bus Isolation

• Ideal for Low-Power Portable Equipment

3 Description

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 Typical DC Voltage-Translation

Characteristics).

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 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 VCC through a

pullup resistor; the minimum value of the resistor is

determined by the current-sinking capability of the

driver.