RF synthesizer with VCO — what it does and where it fits
The Texas Instruments LMX2571NJKT is a PLLatinum™ RF frequency synthesizer with an integrated VCO, designed to generate clock signals up to 1.4 GHz from a crystal or clock input. It includes a PLL with bypass mode, which means the part can operate either as a closed-loop synthesizer or as a direct VCO — useful when you need to switch between locked precision and wideband modulation in the same design. The single-circuit device accepts two clock or crystal inputs and delivers two clock outputs, though the outputs are single-ended (no differential pair). Typical applications include wireless infrastructure, test equipment, and RF signal chains where a clean, programmable local oscillator is needed. The -40°C to 85°C temperature range covers most industrial and telecom enclosures, but not extended automotive or under-hood environments.
Supply rail tolerance — plan for a clean 3.3 V
The supply range is 3.15 V to 3.45 V.
Package and mounting — 36-WQFN with exposed pad
The LMX2571NJKT comes in a 36-lead WFQFN with an exposed pad (6x6 mm body). The exposed pad is the thermal and electrical ground path — it must be soldered to a PCB ground plane with adequate thermal vias. Reflow is the intended assembly method; hand-soldering this package on site is possible with a hot-air station and a fine-tip iron for the perimeter leads, but the pad underneath needs paste or a preform. No lab bench required, but a standard reflow profile is the reliable path. The part is surface-mount only; no through-hole variant exists.
Lifecycle and sourcing — active, no LTB pressure
The LMX2571NJKT carries an Active product status with ROHS3 compliance. If you are qualifying this into a new BOM, there is no imminent obsolescence risk to plan around.