2.5 F at 5.4 V — double-cell voltage in a single can
The SCMS22D255PRBB0 is a 2.5 F supercapacitor from the KYOCERA AVX SCM series, rated at 5.4 V with a 140 mOhm ESR at 1 kHz. That 5.4 V rating is double what a standard 2.7 V supercapacitor cell delivers, so you can run a single device where you'd otherwise need two cells in series — no balancing resistor network needed, and no voltage-divider losses eating into your hold-up energy. The 0%, +100% tolerance means the part ships with an actual capacitance anywhere from 2.5 F up to 5.0 F. For a backup-timing circuit that triggers at a fixed voltage threshold, the worst-case (2.5 F) sets the minimum hold-up time; the +100% headroom just gives extra margin on the high side without changing the circuit.
Through-hole radial can — board integration and rework
That's a standard through-hole footprint — the leads are thick enough to take a soldering iron without wicking the heat into the cell, and the can body is clearly marked so orientation is obvious under the hot-air station. It's a Bulk package, so you get loose parts in a tube or tray — no tape-and-reel handling concerns. For a bench prototype or a low-volume production run, that means you can hand-place and wave-solder without worrying about reel feed issues.
Temperature range and lifetime — what the ratings mean
The lifetime spec is 1000 hours at 65°C — that's the rated endurance at the maximum operating temperature. At lower temperatures the lifetime extends significantly; at 40°C ambient you can expect several years of continuous service. The 140 mOhm ESR at 1 kHz governs how much peak current the supercapacitor can deliver without excessive self-heating. For a pulse discharge of a few seconds, the voltage drop is I × ESR; a 1 A draw loses 140 mV to the internal resistance, which is manageable for most hold-up circuits. The ESR also sets the ripple-current heating — keep the RMS ripple below the self-heating limit for the ambient temperature.