Table 9-3. Design Parameters for 2.3-V to 4.3-V VBAT Supply With Low to Medium Loss System

PARAMETER

VALUE(1)

2.3 V to 4.3V

No

Edge and DC Boost

BOOST Level

Boost Level 0:

0-Ω

0

1.8 kΩ ±1%

1

3.6 kΩ ±1%

2

Do Not Install (DNI)

3

RX Sensitivity

RX_SEN Level

Medium RX

Sensitivity Level:

22 kΩ - 40 kΩ (27 kΩ typical)

Do Not Install (DNI)

Low

Do Not Install (DNI)

Do Not Install (DNI)

Medium

37.5 kΩ(2)

12.5 kΩ

High

(1)

These parameters are starting values for a low to medium loss system. Further tuning might be required based on specific host and/or

device as well as cable length and loss profile. These settings are not specific to a 2.3V-4.3V supply system could be applicable to 5V

supply system as well.

(2)

This resistor is needed for a VBAT supply (2.3V - 4.3V) to divide the voltage down so the RX_SEN pin voltage does not exceed 5.0V

9.2.2 Detailed Design Procedure

The ideal BOOST setting is dependent upon the signal chain loss characteristics of the target platform. The

recommendation is to start with BOOST level 0, and then increment to BOOST level 1, and so on. Same applies

to the RX sensitivity setting where it is recommended to plan for the required pads or connections to change

boost settings, but to start with RX sensitivity level Low.

In order for the TUSB217A to recognize any change to the BOOST setting, the RSTN pin must be toggled. This

is because the BOOST pin is latched on power up and the pin is ignored thereafter.

Note

The TUSB217A compensates for extra attenuation in the signal path according to the configuration of

the RX_SEN pin. This maximum recommended voltage for this pin is 5 V when selecting the highest

RX sensitivity level.

Placement of the device is also dependent on the application goal. Table 9-4 summarizes our recommendations.

Table 9-4. Platform Placement Guideline

PLATFORM GOAL

SUGGESTED TUSB217A PLACEMENT

Pass USB Near End Mask at the receptacle

Close to measurement point (connector)

Pass USB Far End Eye Mask at the plug

Close to USB PHY

Cascade multiple TUSB217As to improve device enumeration

Midway between each USB interconnect

Table 9-5. Table of Recommended Settings

BOOST and RX_SEN settings (1)for channel loss

Pre-channel cable length (Between USB

PHY and TUSB217A)

BOOST

RX_SEN

0-3 meter

Level 0

Medium or High

2-5 meter

Level 1

Medium or High

Post-channel cable length (Between

TUSB217A and inter-connect)

BOOST

RX_SEN

0-2 meter

Level 0

Medium or High

1-4 meter

Level 1

Medium or High

(1)

These parameters are starting values for different cable lengths. Further tuning might be required based on specific host and/or device

as well as cable length and loss profile.

TUSB217A

SLLSFK5 – JUNE 2021

www.ti.com

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