8 Detailed Description

8.1 Overview

The TUSB217A is a USB High-Speed (HS) signal conditioner designed to compensate for ISI signal loss in a

transmission channel. TUSB217A has a patented design for USB Low Speed (LS) and Full Speed (FS) signals.

It does not alter the signal characteristics. HS signals are compensated. The design is compatible with USB

On-The-Go (OTG) and Battery Charging (BC) specifications.

Programmable signal gain through an external resistor permits fine tuning device performance to optimize

signals. This helps pass USB HS electrical compliance tests at the connector. Additional RX sensitivity, tuned by

external pull-up resistor and pull-down resistor, allows to overcome attenuation in cables. The TUSB217A allows

application in series to cover longer distances, or high loss transmission paths. A maximum of 4 devices can be

daisy-chained.

8.2 Functional Block Diagram

USB

TRANSCEIVER

High Speed

Compensation

USB

CONNECTOR

Low and Full

Speed Bypass

Status flags

OPTIONAL

PLD

ESD

PROTECTION

D2P

D2M

D1P

D1M

CD

ENA_HS

Copyright © 2018, Texas Instruments Incorporated

8.3 Feature Description

8.3.1 High-speed Boost

The high-speed booster (combination of edge boost and DC boost) improves the eye width for USB2.0 high-

speed signals. It is direction independent and by that is compatible to OTG systems. The BOOST pin is

configuring the booster strength with different values of pull down resistors to set 4 levels of boosts, alternatively

the boost level can be set via I2C register according to Section 8.4.6. Internal circuitry of the signal conditioner

reduces possible overshoot.

8.3.2 RX Sensitivity

The RX_SEN pin is a tri-level pin. It is used to set the equalization gain of the device according to system

channel inter-symbol interference (ISI) loss. RX equalization can be increased to compensate for the higher ISI

loss of the channel for example due to a long cable.

8.4 Device Functional Modes

8.4.1 Low-speed (LS) Mode

TUSB217A automatically detects a LS connection and does not enable signal compensation. CD pin is asserted

high but ENA_HS will be low.

8.4.2 Full-speed (FS) Mode

TUSB217A automatically detects a FS connection and does not enable signal compensation. CD pin is asserted

high but ENA_HS will be low

8.4.3 High-speed (HS) Mode

TUSB217A automatically detects a HS connection and will enable signal compensation as determined by the

configuration of the RX_SEN pin and the external pull down resistance on its BOOST pin.

CD pin and ENA_HS pin are asserted high when high-speed boost is active.

TUSB217A

SLLSFK5 – JUNE 2021

www.ti.com

10

Submit Document Feedback

Copyright © 2021 Texas Instruments Incorporated

Product Folder Links: TUSB217A