SNAS783C June 2020 – February 2021 LMX2820
PRODUCTION DATA
Lock detect gives a rough indication of whether or not the PLL is in lock. There are two general types of lock detect supported: calibration status and indirect vtune. The calibration status lock detect starts low when the VCO begins cailbration. If LD_VTUNE_EN=1, then an additional 4xLD_DLY phase detector cycles is added to this delay. The indirect vtune lock detect works by creating an indirect internal voltage that is intended to mimic the actual voltage at the VTUNE pin. When this voltage goes out of range, the Vtune lock detect is low. The calibration status and Vtune lock detect can be combined as well. In situations where the VCO calibration is bypassed, such as full assist mode or instant calibration, then this lock detect serves just the Vtune function.