6.3 Feature Description

6.3.1 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 TUSB542 receiver. The receiver overcomes these losses by providing gain

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

setting should be selected to match the channel insertion loss before the receiver input of the TUSB542.

6.3.2 De-Emphasis Control and Output Swing

The output differential drivers of the TUSB542 provide selectable de-emphasis and output swing to achieve

USB3.1 compliance, these options are configurable by means of 3-state control pins, and its available settings

are listed on the Table 6-2. The level of de-emphasis required in the system depends on the channel length after

the output of the re-driver. Figure 6-2 shows transmit bits with de-emphasis.

± 0.5 V

0 V

0.5 V

0ps

200ps

400ps

600ps

800ps

1000ps

1200ps

DE = 0 dB

DE = ± 3.5 dB

DE = ± 6 dB

DE = ± 6 dB

DE = ± 3.5 dB

DE = 0 dB

Transition Bit

Consecutive Bits

Transition Bit

Consecutive Bits

VTX-DIFF-PP

Figure 6-2. Transmitter Differential Voltage in Presence of De-Emphasis

6.3.3 Automatic LFPS Detection

The TUSB542 features an intelligent low frequency periodic signaling (LFPS) controller. The controller senses

the low frequency signals and automatically disables the driver de-emphasis, for full USB3.1 compliance.

6.3.4 Automatic Power Management

The TUSB542 deploys RX detect, LFPS signal detection and signal monitoring to implement an automatic power

management scheme to provide active, U2/U3 and disconnect modes. The automatic power management is

driven by an advanced state machine, which is implemented to manage the device such that the re-driver

operates smoothly in the links.

6.4 Device Functional Modes

6.4.1 Disconnect Mode

The Disconnect mode is the lowest power state of the TUSB542. In this state, the TUSB542 periodically checks

for far-end receiver termination on both TX. Upon detection of the far-end receiver’s termination on both ports,

the TUSB542 will transition to U0 mode.

6.4.2 U Modes

6.4.2.1 U0 Mode

The U0 mode is the highest power state of the TUSB542. Anytime super-speed traffic is being received, the

TUSB542 remains in this mode.

6.4.2.2 U2/U3 Mode

Next to the disconnect mode, the U2/U3 mode is next lowest power state. While in this mode, the TUSB542

periodically performs far-end receiver detection.

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TUSB542

SLLSER3F – DECEMBER 2015 – REVISED DECEMBER 2023

Copyright © 2023 Texas Instruments Incorporated

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Product Folder Links: TUSB542