TUSB1004 datasheet(23/53 Pages) TI

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7.3.3.2 Limited VOD

Limited VOD mode is used to set the actual VOD level and is used when TUSB1004 is configured in limited

redriver mode. In this mode the VOD is no longer a linear function of the input VID. For example, if the signal at

TUSB1004's input (VID) is at 600 mVpp then the TUSB1004's output VOD will be around 1000 mVpp (assuming

LINR_L3 is selected). The limited redriver mode is only supported on the SSRX1/2 transmitter. The TUSB1004

provides four different limited VOD settings. All four settings are available through register control.

Note

Limited redriver mode is disabled by default and can only be enabled by setting the

SSRX_LIMIT_ENABLE register. Once enabled, the VOD level for SSRX1/2 transmitters is controlled

by the USB_SSRX12_VOD register

7.3.3.3 Transmit Equalization (Limited Redriver Mode Only)

The TUSB1004 in limited redriver mode offers pre-shoot and de-emphasis controls for SSRX1/2 transmitter. The

TUSB1004 offers four pre-shoot levels and four de-emphasis levels. These levels can be changed by modifying

I2C registers.

SSRX1 transmitter equalization is controlled by TX1_PRESHOOT and TX1_DEEMPHASIS fields. When

SSRX_LIMIT_ENABLE = 1 and TX1_PRESHOOT_EN = 1, the TX1_PRESHOOT field selects between

four different pre-shoot levels. When SSRX_LIMIT_ENABLE = 1 and TX1_DEEMPHASIS_EN = 1, the

TX1_DEEMPHASIS field selects between four different de-emphasis levels.

SSRX2 transmitter equalization is controlled by TX2_PRESHOOT and TX2_DEEMPHASIS fields. When

SSRX_LIMIT_ENABLE = 1 and TX2_PRESHOOT_EN = 1, the TX2_PRESHOOT field selects between

four different pre-shoot levels. When SSRX_LIMIT_ENABLE = 1 and TX2_DEEMPHASIS_EN = 1, the

TX2_DEEMPHASIS field selects between four different de-emphasis levels.

Note

Transmitter equalization control is not supported in pin-strap mode.

7.3.4 USB 3.1 x2 Description

The TUSB1004 will operate as two independent USB state machines. The TUSB1004 is intended to be used

in applications that support USB stacked standard A connectors or two standard-A connectors that are in close

proximity to each other.

In pin-strap mode the TUSB1004 will enable both lanes for USB operation immediately following EN pin high. In

I2C mode, software must program register offset 0xD to a 0x03 and it also must program CTLSEL field (located

in offset 0xA) to a 1 for both lanes to be enabled for USB operation.

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TUSB1004

SLLSFL3 – APRIL 2022

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