SLLSFB2 April 2020 TUSB1146
PRODUCTION DATA.
Configuring the TUSB1146 for the USB and DP downstream direction involves understanding the insertion loss (SDD21) of the pre-channel (XAB and XCD). The TUSB1146's DPEQ[1:0] pins and SSEQ[1:0] pins if GPIO mode ,or if I2C mode, SSEQ_SEL and DPEQx_SEL registers should be set to the level of the pre-channel insertion loss at 5GHz. A good rule of thumb for FR4 trace insertion loss at 5GHz is ~-1dB per inch. Using this rule of thumb, if the pre-channel for USB (XAB) is 8-inches, the TUSB1146 SSEQ should be programmed to -8dB. If the pre-channel insertion loss for DP (XCD) is 10-inches, then DPEQ should be programmed to -10dB. Refer to Table 8 for USB SSEQ settings and to Table 9 for DP EQ settings.