8.1.2 Low-Power Optimization

The LMH1228 IN0 CTLE operates in either AM1 Adaptive Mode or AM0 Manual Mode. When operating in AM1, the LMH1228 uses HEO/VEO Lock Monitoring as a key parameter to achieve lock. HEO/VEO Lock Monitoring determines the CTLE boost setting that produces the best horizontal and vertical eye opening after the CTLE. Once AM1 adaptation is complete and the LMH1228 asserts CDR lock at the optimal IN0 CTLE setting, HEO/VEO Lock Monitoring is no longer required to maintain lock. Therefore, HEO/VEO Lock Monitoring can be disabled by setting CTLE/CDR Reg 0x3E[7] = 0'b after lock is declared. Disabling HEO/VEO Lock Monitoring optimizes power dissipation, reducing the overall power by approximately 25 mW.

When operating in AM0, the LMH1228 does not use HEO/VEO Lock Monitoring, because the IN0 CTLE setting is set manually by the user. In AM0, HEO/VEO Lock Monitoring can be disabled at any time.