7 Application and Implementation

Note

Information in the following applications sections is not part of the TI component specification,

and TI does not warrant its accuracy or completeness. TI’s customers are responsible for

determining suitability of components for their purposes, as well as validating and testing their design

implementation to confirm system functionality.

7.1 Application Information

There are many USB applications in which the USB hubs or controllers have a limited number of USB I/Os. The

TS3USB221E can effectively expand the limited USB I/Os by switching between multiple USB buses to interface

them to a single USB hub or controller. The TS3USB221E can also be used to connect a single controller to two

USB connectors.

7.2 Typical Application

TS3USB221E

2-channel

SPDT

VCC

S

OE

D+

D-

GND

System

Controller

USB Port 1

USB Port 2

0.1 F

μ

0.1 F

μ

3.3 V

USB

Controller

Switch

Control Logic

2D+

2D-

1D+

1D-

Figure 7-1. Simplified Schematic

7.2.1 Design Requirements

Follow the design requirements of the USB 1.0, 1.1, and 2.0 standards.

TI recommends that the digital control pins S and OE be pulled up to VCC or down to GND to avoid undesired

switch positions that could result from the floating pin.

7.2.2 Detailed Design Procedure

The TS3USB221E can be properly operated without any external components. However, TI recommends to

connect any unused pins to ground through a 50-Ω resistor to prevent signal reflections back into the device.

www.ti.com

TS3USB221E

SCDS263E – SEPTEMBER 2009 – REVISED JULY 2024

Copyright © 2024 Texas Instruments Incorporated

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Product Folder Links: TS3USB221E