The LMK5C22212A has two reference inputs, two digital PLLs (DPLL), two analog PLLs (APLLs) with integrated VCOs, and twelve output clocks. APLL1 uses an ultra-high performance BAW VCO (VCBO) with a very high quality factor, and thus minimizes dependency on the phase noise or frequency of the external oscillator (XO) input clock. TI's VCBO technology reduces the overall solution cost to meet the free-run and holdover frequency stability requirements. An XO, TCXO, or OCXO must be selected based on system holdover stability requirements. APLL1 can be controlled by the corresponding DPLL1, allowing the APLL1 domain to be locked to the DPLL1 reference input for synchronous clock generation. The DPLL2/APLL2 similarly can be locked to the same referenced input as DPLL1 or locked to a separate reference input to create another synchronization domain. Each APLL can select a reference from either XO port or another APLL divided clock. The DPLL can select a synchronization input reference from reference inputs INx or align to another APLL domain by selecting feedback from a cascade dividers.

The DPLL reference input mux supports automatic input selection based on priority and reference signal monitoring criteria. Manual input selection is also possible through software or pin control. The device provides Hitless Switching between reference sources with proprietary phase cancellation and phase slew control for superior phase transient performance. The Reference Input Monitoring block monitors the clock inputs and performs a hitless switchover or holdover when a loss of reference (LOR) is detected. A LOR condition is detected upon any violation of the threshold limits set for the input monitors, which include frequency, missing and early pulse, runt pulse, and 1PPS (pulse-per-second) detectors. The threshold limits for each input detector can be set and enabled per reference clock input. The Tuning Word History monitor feature determines the initial output frequency accuracy upon entry into holdover based on the historical average frequency when locked, thereby minimizing the frequency and phase disturbance during a LOR condition.

The LMK5C22212A has twelve outputs with programmable output driver types, allowing up to twelve differential clocks or a combination of differential and single-ended clocks). Up to four single-ended 1.8V or 2.65V LVCMOS output clocks (each from _P and _N outputs from OUT0 and OUT1) can be configured with ten differential output clocks. Each output clock derives from one of two APLL/VCO domains through the output muxes. Output 0 (OUT0) and Output 1 (OUT1) are the most flexible and can select the source from the XO, reference input, or any APLL domain. A CMOS 1PPS output can be supported on Outputs 0 (OUT0) and Output 1 (OUT1). The output dividers have a SYNC feature to allow multiple outputs to be phase-aligned. Zero-Delay Mode (ZDM) can also achieve a deterministic phase alignment between a clock from DPLL1 or DPLL2 presented to OUT0 and the selected reference input. An alternate ZDM feedback path is available on OUT10 for DPLL1 and OUT4 for DPLL2.

To support IEEE 1588 PTP secondary clock or other clock steering applications, the DPLL supports DCO mode with less than 1ppt (part per trillion) frequency resolution for precise frequency and phase adjustment through software or pin control.

The device is fully programmable through I²C or SPI and supports start-up frequency configuration with factory preprogrammed internal ROM pages. A programmable EEPROM Overlay, which allows POR configuration of registers related to APLL and output configuration, provides flexible power up output clocks. The DPLL configuration is not set by EEPROM values, but initialized based on the ROM Page Selection, and fully programmable using the serial control interface. Internal LDO regulators provide excellent PSNR to reduce the cost and complexity of the power delivery network. The clock input and PLL monitoring status are visible through the GPIO status pins and interrupt registers readback for full diagnostic capability.