What the 1.08 GHz PLL buys you in a clock tree
The LMK04131SQX/NOPB is a single-circuit PLL clock conditioner from TI's PLLatinum family, rated to 1.08 GHz maximum frequency. That ceiling covers most RF and high-speed serial datapath clocks — 10G Ethernet reference, FPGA transceiver lanes, ADC/DAC sampling clocks — without needing a separate frequency multiplier stage upstream. The 2:6 input-to-output fanout ratio means it accepts two reference inputs (LVCMOS, LVDS, or LVPECL) and distributes six cleaned-up clock outputs in the same differential or single-ended formats. On a mixed-signal board, that saves a separate fanout buffer and keeps the jitter budget tight across all loads.
Package and rework reality
Housed in a 48-lead WFQFN with exposed pad (7x7 mm WQFN), the part sits on a thermal land that must be soldered to a PCB copper plane for both heat sinking and ground return. Reworking this package under hot air is straightforward if the board has a bottom-side preheat zone. The 0.5 mm pitch QFN leads are visible at the edges for inspection, and the centre pad wets through a solder paste stencil opening about 50% of the pad area — too much paste and the part floats, too little and the thermal connection opens under temperature cycling.
Active production — no LTB pressure
Supply voltage is a tight 3.15 V to 3.45 V rail — not a wide-range 3.3 V part. The board's 3.3 V rail must stay within that window under load; a switching regulator with 2% set-point accuracy and 50 mV ripple keeps the PLL's internal VCO from pulling frequency on the supply noise.