200 MHz PLL clock generator in a 4x4 mm LFCSP
The ADF4001BCPZ is a phase-locked loop (PLL) clock generator from Analog Devices, built for RF synthesis applications where a clean, stable clock is needed from a lower-frequency reference. It accepts CMOS or TTL inputs and delivers a single clock output at frequencies up to 200 MHz. The 2:1 input-to-output ratio means the chip can select between two reference sources or divide the PLL output internally — useful when the system has a primary and a backup oscillator.
The wide supply range lets the ADF4001BCPZ run directly off a 3.3 V or 5 V rail without a local LDO. That saves a regulator and a couple of bypass caps on the BOM, but the trade-off is that the PLL charge-pump current and loop-filter component values need to be recalculated if the supply voltage changes between designs. Industrial temperature grade qualifies the part for outdoor and factory-floor environments where the ambient can hit 85 °C — common in telecom base stations, motor drives, and instrumentation.
Active production — no obsolescence risk
It ships in a tray — the 20-LFCSP (4x4) package is a standard 4 mm × 4 mm QFN-style footprint with an exposed pad that must be soldered to a thermal land on the PCB for rated heat dissipation.
Package and footprint notes for layout
The 20-WFQFN exposed-pad package has a 0.50 mm pitch. The centre pad is the primary thermal path — the PCB land pattern should include a grid of thermal vias to a ground plane, and the pad must be connected to the ground plane (or the appropriate supply rail) per the datasheet recommendation. Differential input and output capability means the reference and the PLL output can be routed as differential pairs, which helps reject common-mode noise on long board traces or through connectors.