4.7 µF at 50 V — the derating margin that keeps the rail clean
The TAJY475K050RNJ is a molded tantalum capacitor from KYOCERA AVX's TAJ series, rated at 4.7 µF with ±10% tolerance and a 50 V working voltage. On a 24 V or 28 V rail, the 50 V rating gives a 2:1 derating margin — the standard practice to keep the capacitor's failure rate below 1 FIT in avionics or satellite power supplies. The 1.2 Ohm ESR at 100 kHz sets the ripple current ceiling: at 50 °C ambient, the part can handle roughly 0.8 A ripple before self-heating pushes the core temperature past the 125 °C limit.
KYOCERA AVX continues to manufacture the TAJ series in the 2917 case code.
Molded case, 2917 footprint — board-fit checklist
The 2917 (7343 Metric) molded case measures 7.30 mm x 4.30 mm with a seated height of 2.00 mm max. The Y case code matches the standard 2917 land pattern per EIA-535-BAAC. The molded epoxy body is non-hermetic — for high-humidity environments (condensing, washdown), a conformal coat over the assembly is recommended to prevent silver migration at the terminations.
The capacitance change over temperature is ±10% typical across the range — within the stated tolerance band.