SLLSF89A September 2018 – December 2018 TUSB217-Q1
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. if permissible. 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 1.
In order for the TUSB217-Q1 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.
The TUSB217-Q1 compensates for extra attenuation in the signal path according to the configuration of the RX_SEN pin. This pin is not 5 V tolerant and therefore when selecting the highest RX sensitivity level, the voltage level at RX_SEN pin must be less than 3.6V.
Placement of the device is also dependent on the application goal. Table 11 summarizes our recommendations.
|PLATFORM GOAL||SUGGESTED TUSB217-Q1 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 TUSB217s to improve device enumeration||Midway between each USB interconnect|
|BOOST and RX_SEN settings (1)for channel loss|
|Pre-channel cable length (Between USB PHY and TUSB217-Q1)||BOOST||RX_SEN|
|0-3 meter||Level 0||Medium or High|
|2-5 meter||Level 1||Medium or High|
|Post-channel cable length (Between TUSB217-Q1 and inter-connect)||BOOST||RX_SEN|
|0-2 meter||Level 0||Medium or High|
|1-4 meter||Level 1||Medium or High|