6 Detailed Description

6.1 Overview

TUSB542 is an active re-driver for USB 3.1 Gen1 applications; it supports Type-C applications, as well as

switching between two Hosts and one device (or vice versa). The device is a dual channel USB 3.1 Gen1

(5Gbps) re-driver supporting systems with USB Type-C connectors. The TUSB542 can be controlled through

the SEL, and is best controlled using an external Configuration Channel Logic or Power Delivery Controller to

properly mux the signals in Type-C applications.

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

inter-symbol interference. The TUSB542 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 3.1 compliance.

The TUSB542 advanced state machine makes it transparent to hosts and devices. After power up, the TUSB542

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

enabled, and the TUSB542 is ready to re-drive.

The TUSB542 operates over the industrial temperature range of –40°C to 85°C in the 2 mm x 2.4 mm X2QFN

package. The device ultra-low power architecture operates at a 1.8V power supply. The automatic LFPS

DeEmphasis control further enables the system to be USB 3.0 compliant. An advanced state machine inside

the device monitors the USB SS traffic to perform enhanced power management to operate in no-connect, U2,

U3 and active modes.

The USB Type-C connector is designed to allow insertion either upside-up or downside-up. The TUSB542

supports this feature by routing the AP signals to one of two output channels. The SEL input control defines the

way that the AP side signals is routed on the re-driver device side. Table 6-1 lists the active MUX configurations

based on the SEL input.

Table 6-1. USB SS MUX Control

SEL

Tx_Con_1

Rx_Con_1

Tx_Con_2

Rx_Con_2

H

TX_AP

RX_AP

GND

GND (1)

L

GND

GND (1)

TX_AP

RX_AP

(1)

Terminated through 50 K (minimum) resistors

The TUSB542 has flexible configurations to optimize the device using GPIO control pins. Figure 6-1 shows a

typical signal chain for mobile applications. Channel 1 is between Application Processor (AP) and TUSB542,

Channel 2 is between the TUSB542 redriver and the downstream device. The CNFG_A1 and CNFG_B1 pins

provide signal integrity configuration settings for channel 1, while CNFG_A2 and CNFG_B2 pins control the

operation of Channel 2 as listed in Table 6-2.

Flexible Cable + Sub-Board

Main Board

TUSB542

Ch. 1

Ch. 2

DE_CON

OS_CON

DE_AP

OS_AP

EQ_AP

EQ_CON

Figure 6-1. Typical Channels

The receiver (RX) of the device provides the flexibility of 0, 3, 6 and 9dB of equalization, while the transmitter

(TX) provides the options of 0, 3.5 or 6dB de-emphasis. The transmitter also supports output swing settings of

900 mV and 1.1V.

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TUSB542

SLLSER3F – DECEMBER 2015 – REVISED DECEMBER 2023

Copyright © 2023 Texas Instruments Incorporated

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Product Folder Links: TUSB542