SNLS477B October 2014 – November 2018 DS90UB948-Q1
The user can program the AEQ circuit with the minimum AEQ level setting used during the EQ adaption. Using the full AEQ range will provide the most flexible solution, however, if the channel conditions are known and an improved deserializer lock time can be achieved by narrowing the search window for allowable EQ gain settings. For example, in a system use case with a longer cable and multiple interconnects creating a higher channel attenuation, the AEQ would not adapt to the minimum EQ gain settings. In this case, starting the adaptation from a higher AEQ level would improve lock time. The AEQ range is determined by the AEQ_CTL2 register 0x45 where the ADAPTIVE_EQ_FLOOR_VALUE determines the starting value for EQ gain adaption. The maximum AEQ limit is not adjustable. To enable the minimum AEQ limit, OVERRIDE_AEQ_FLOOR and SET_AEQ_FLOOR bits in the AEQ_CTL1 register must also be set. The setting for the AEQ after adaption can be readback from the AEQ_STATUS register 0x3B.