1.57 GHz clock conditioner — what the PLL buys you
The LMK04001BISQE/NOPB is a Texas Instruments clock conditioner with an integrated PLL that cleans up jitter on reference clocks and synthesizes clean output frequencies up to 1.57 GHz. It accepts LVCMOS, LVDS, or LVPECL inputs and can deliver LVCMOS, 2VPECL, or LVPECL outputs, making it a protocol-agnostic bridge between different logic families on a mixed-signal board.
The supply range is 3.15 V to 3.45 V, a narrow window that keeps the internal VCO and PLL charge pump well-regulated — plan for a clean 3.3 V rail with <50 mV ripple.
2:7 fanout and divider/multiplier flexibility
The 2:7 input-to-output ratio lets one reference clock feed up to seven downstream devices while the divider and multiplier stages adjust the frequency. This is useful when a single oscillator must drive multiple FPGAs, SERDES, or ADCs at different clock rates — the PLL locks to the reference and the dividers generate the lower-speed copies.
48-WQFN with exposed pad — layout checklist
The exposed paddle is the primary thermal path and also serves as the ground return for the PLL — a solid connection here is non-negotiable for jitter performance.
No official second-source or pin-compatible cross-reference is listed, so the BOM is single-sourced to this TI part number.