RX+

RX-

TX+

TX-

LFPS

Controller

EQ

Driver

Receiver

/

Equalizer

DE

OS

Advanced

State Machine

GND

VCC

TUSB551

www.ti.com

SLLSEJ1A – MARCH 2014 – REVISED MARCH 2014

8 Detailed Description

8.1 Overview

When 5Gbps SuperSpeed USB signals travel across a PCB or cable, signal integrity degrades due to loss and

inter-symbol interference. The TUSB551 recovers incoming data by applying equalization that compensates for

channel loss, and drives out signals with a high differential voltage. This extends the possible channel length,

and enables systems to pass USB 3.0 compliance.

The TUSB551 advanced state machine makes it transparent to hosts and devices. After power up, the TUSB551

periodically performs receiver detection on the TX pair. If it detects a SuperSpeed USB receiver, the RX

termination is enabled, and the TUSB551 is ready to re-drive.

The device’s ultra low-power architecture operates at a 1.8V power supply and achieves enhanced performance.

The receiver equalizer has three gain settings that are controlled by terminal EQ: 3 dB, 6 dB, and 9 dB. The

equalization should be set based on amount of insertion loss in the channel before the TUSB551. Likewise, the

output driver supports configuration of De-Emphasis and Output Swing (terminals DE and OS). The automatic

LFPS De-Emphasis control further enables the system to be USB3.0 compliant.

The TUSB551 operates over the industrial temperature range of -40ºC to 85ºC in the 1.6mm x 1.6mm X2QFN

package.

8.2 Functional Block Diagram

8.3 Feature Description

8.3.1 Receiver Equalization

The purpose of receiver equalization is to compensate for channel insertion loss and inter-symbol interference in

the system before the input of the TUSB551. The receiver overcomes these losses by attenuating the low

frequency components of the signals with respect to the high frequency components. The proper gain setting

should be selected to match the channel insertion loss before the input of the TUSB551.

8.3.2 De-Emphasis Control and Output Swing

The differential driver output provides selectable de-emphasis and output swing control in order to achieve

USB3.0 compliance. The TUSB551 offers a unique way to adjust output de-emphasis and transmitter swing

based on the OS and DE terminals. The level of de-emphasis required in the system depends on the channel

length after the output of the re-driver.

Copyright © 2014, Texas Instruments Incorporated

Submit Documentation Feedback

9

Product Folder Links: TUSB551