600 mF at 8.1 V — sizing the hold-up bank
The SCMR18J604SRBA0 is a 600 mF supercapacitor rated at 8.1 V, part of KYOCERA AVX's SCM series. This capacitance and voltage combination suits it for short-term hold-up, power-fail buffering, and peak-power assist in circuits where a battery would be oversized or have limited cycle life. The 400 mOhm ESR at 1 kHz means the internal resistance is low enough to deliver a few amps of pulse current without the voltage sag eating into the downstream regulator's dropout margin. For a 1 A pulse, the IR drop is 0.4 V, leaving 7.7 V at the terminals — enough headroom for a 5 V rail.
Temperature envelope and lifetime — the real duty cycle
Rated for 1000 hours at 65°C, with an operating range of -40°C to 65°C. The lifetime figure is the endurance at the top temperature; at 45°C ambient the expected life roughly doubles per 10°C drop, so a 45°C application sees about 4000 hours before the capacitance drifts out of the -10%/+30% tolerance band. The -10%/+30% tolerance means the minimum capacitance at end of life is 540 mF, and the initial value can be as high as 780 mF. A hold-up time calculation should use the 540 mF floor to guarantee the minimum backup duration across production lots and temperature.
Active production — sourcing for the BOM line
The radial can with 0.531-inch (13.50 mm) lead spacing and PC pin termination fits standard through-hole footprints. The 24.00 mm x 8.00 mm body with a seated height of 19.50 mm requires 0.945 inches of board length — verify clearance against adjacent tall components.