SN74CB3Q3125_15 Datasheet, PDF (8/26 Pages) Texas Instruments – Quadruple FET Bus Switch

SN74CB3Q3125
SCDS143C – OCTOBER 2003 – REVISED JUNE 2015
8 Detailed Description
www.ti.com
8.1 Overview
The SN74CB3Q3125 device is a high-bandwidth FET bus switch utilizing a charge pump to elevate the gate
voltage of the pass transistor, providing a low and flat ON-state resistance (r_on). The low and flat ON-state
resistance allows for minimal propagation delay and supports rail-to-rail switching on the data input/output (I/O)
ports. The SN74CB3Q3125 device also features low data I/O capacitance to minimize capacitive loading and
signal distortion on the data bus. Specifically designed to support high-bandwidth applications, the
SN74CB3Q3125 device provides an optimized interface solution ideally suited for broadband communications,
networking, and data-intensive computing systems.
The SN74CB3Q3125 device 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 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 circuitry prevents damaging
current 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.
A
B
V_CC
Charge
Pump
EN⁽¹⁾
Figure 4. Simplified Schematic, Each FET Switch (SW)
8.2 Functional Block Diagram
2
1A
1
1OE
3
SW
1B
5
2A
4
2OE
6
SW
2B
9
3A
10
3OE
8
SW
3B
12
4A
13
4OE
11
SW
4B
8
Submit Documentation Feedback
Copyright © 2003–2015, Texas Instruments Incorporated
Product Folder Links: SN74CB3Q3125