± 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

13

TUSB542

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SLLSER3B – DECEMBER 2015 – REVISED JANUARY 2016

Product Folder Links: TUSB542

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Copyright © 2015–2016, Texas Instruments Incorporated

7.3 Feature Description

7.3.1 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.

7.3.2 De-Emphasis Control and Output Swing

The output differential drivers of the TUSB542 provide selectable De-Emphasis and output swing in order 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 2. The level of de-emphasis required in the system depends on the channel

length after the output of the re-driver. Figure 14 shows transmit bits with De-Emphasis.

Figure 14. Transmitter Differential Voltage in Presence of De-Emphasis

7.3.3 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.

7.3.4 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.