The Infineon BBY5502VH6327XTSA1 is a single silicon varactor diode in a SC-79 / SOD-523 surface-mount package, designed for voltage-controlled tuning in RF circuits. Its key parameters are a peak reverse voltage of 16 V, a capacitance of 6.5 pF at 10 V and 1 MHz, and a capacitance ratio of 3 measured between 2 V and 10 V reverse bias (C2/C10). Typical applications include VCO tank circuits, bandpass filter tuning, and phase-locked-loop frequency adjustment in telecom infrastructure, automotive RF modules, and portable radios.
The capacitance ratio of 3 (C2/C10) means the diode's capacitance changes by a factor of three as the reverse bias swings from 2 V to 10 V. That directly sets the frequency tuning range of a VCO or filter.
16 V peak reverse — sizing the tuning supply
The 16 V peak reverse rating sets the maximum DC bias you can apply. In practice, you'll run the tuning voltage below that to leave headroom for ripple and temperature drift.
The SC-79 / SOD-523 package is a two-pin surface-mount case. The supplier device package is PG-SC79-2. It's a single diode, so the cathode is marked by a bar on the body.
It's a current-production Infineon part, so you can qualify it into new designs without worrying about a near-term phase-out.