SLLSFB2 April 2020 TUSB1146
PRODUCTION DATA.
In Fixed EQ operation, a single EQ setting is used for all possible devices inserted into the USB-C receptacle (with or without USB cable). It is recommended to set TUSB1146 EQ[1:0] pins if GPIO mode, or EQ1_SEL and EQ2_SEL if I2C mode to about 4db to 5dB greater than loss of the post channel (MIN(XEF, XGH)). For example, if post channel is 0.5 inches, then assuming -1dB per inch at 5GHz, EQ1_SEL and EQ2_SEL should be programmed to 4.5 to 5.5dB. It is recommended to perform USB3.1 Rx JTOL long and short channel tests to optimize the setting. Depending of the USB 3.1 Host, a single EQ setting which satisfies both the long and short channel tests may not be possible. If this is the case, then it is recommended to use Fast AEQ mode.