SNAS750B November 2020 – March 2021 LMK5C33216
PRODUCTION DATA
Figure 9-2 shows the PLL architecture implemented in the LMK5C33216. APLL1 with integrated LC VCO (VCO1) can be used as a clock generation domain. APLL1's numerator in feedback N divider can be controlled by DPLL1. APLL2 with integrated LC VCO (VCO2) can generate another additional clock domain. APLL2's numerator in feedback N divider can be controlled by DPLL2. The third channel consists of a digital PLL (DPLL3) and analog PLL (APLL3) with integrated BAW VBCO (VCO3).
The DPLL is comprised of a time-to-digital converter (TDC), digital loop filter (DLF), and programmable 40-bit fractional feedback (FB) divider with sigma-delta-modulator (SDM). The APLLs are comprised of a reference (R) divider, phase-frequency detector (PFD), loop filter (LF), fractional feedback (N) divider with SDM, and VCO.
Each DPLL has a reference selection mux that allows the DPLL to be either locked to another APLL's VCO domian (DPLL Cascaded, except APLL2) or locked to the reference input (Non-Cascaded) providing unique flexibility in frequency and phase control across multiple clock domains..
Each APLL has a reference selection mux that allows the APLL to be either locked to another APLL's VCO domain (APLL Cascaded) or locked to the XO input (Non-Cascaded).
Do not cascade one VCO output to both the DPLL reference and APLL reference of the same DPLL/APLL pair.
Each APLL has a fixed 40 bit denominator controllable by the DPLL. When operating an APLL without the DPLL, a programmable 24 bit denominator is also available allowing an APLL to cascade between frequency domains with 0 ppm frequency error.
Any unused DPLL or APLL should be disabled (powered-down) to save power. Each APLL's VCO drives the clock distribution blocks via their respective VCO post-dividers. If the post-divider setting is 1 for VCO3, the post-divider is bypassed and VCO3 feeds the output clock distribution blocks directly.
The following sections describe the basic principles of DPLL and APLL operation.. See Section 9.4.2 for more details on the PLL modes of operation including holdover.