Undershoot Protection for Off-Isolation on
A and B Ports Up To −2 V
Bidirectional Data Flow, With Near-Zero
Propagation Delay
Low ON-State Resistance (ron)
Characteristics (ron = 3 Ω Typical)
Low Input/Output Capacitance Minimizes
Loading and Signal Distortion
(Cio(OFF) = 5 pF Typical)
Data and Control Inputs Provide
Undershoot Clamp Diodes
Low Power Consumption
(ICC = 3 μA Max)
VCC Operating Range From 4 V to 5.5 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 100 mA Per
JESD 78, Class II
ESD Performance Tested Per JESD 22
− 2000-V Human-Body Model
(A114-B, Class II)
− 1000-V Charged-Device Model (C101)
Supports Both Digital and Analog
Applications: USB Interface, Bus Isolation,
Low-Distortion Signal Gating

description/ordering information
The SN74CBT3125C is a high-speed TTL-compatible FET bus switch with low ON-state resistance (ron),
allowing for minimal propagation delay. Active Undershoot-Protection Circuitry on the A and B ports of the
SN74CBT3125C provides protection for undershoot up to −2 V by sensing an undershoot event and ensuring
that the switch remains in the proper OFF state.
The SN74CBT3125C 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.