SLLSFB2 April 2020 TUSB1146
PRODUCTION DATA.
Fast Adaptive EQ will distinguish between a short and long channel and select a pre-determined EQ setting based on which channel is detected. Fast AEQ is available in both GPIO and I2C mode but it is highly recommended to use this feature when TUSB1146 is configured in I2C mode. In I2C mode Fast AEQ is enabled when AEQ_MODE = 0 and AEQ_EN = 1.
The EQ setting used for short channel should be programmed into EQ1_SEL and EQ2_SEL registers. It is recommended to program these registers about 1dB to 2dB more than the loss of post channel (MIN(XEF, XGH)). For example, if post channel is 0.5 inches, then assuming -1dB insertion loss per inch at 5GHz, EQ1_SEL and EQ2_SEL should be programmed to 1.5 to 2.5dB. It is recommended to perform USB3.1 Rx JTOL Short channel test to find the optimal short channel setting.
The EQ setting used for long channel should be programmed into LONG_EQ1 and LONG_EQ2. It is recommended to program these registers about 4 to 5dB more than the loss of post channel (MIN(XEF, XGH)). For example, if post channel is 0.5 inches, then assuming -1dB per inch at 5GHz, LONG_EQ1 and LONG_EQ2 should be programmed to 4.5 to 5.5dB. It is recommended to perform USB3.1 Rx JTOL Long channel test to find the optimal long channel setting.