4.7 µF at 35 V — the bulk decoupling sweet spot
This TAJC475M035HNJ is a molded tantalum capacitor from the TAJ series, rated 4.7 µF at 35 V with ±20% tolerance. The 35 V rating gives headroom on a 12 V or 24 V rail — the derating rule of thumb (50 % of rated voltage for solid tantalum) still leaves 17.5 V of margin, covering most 12 V bus transients without exceeding the safe operating area. For a 100 kHz buck converter output, the ripple current through this cap is limited by self-heating: at 2.2 ohm, a 500 mA RMS ripple produces 0.55 W of internal dissipation — enough to raise the part temperature 10-15 °C above ambient. Keep the RMS ripple below 400 mA if the board sits in a 85 °C environment.
The molded package (2312 / 6032 metric) is a standard footprint for surface-mount assembly on FR-4 or polyimide boards.
No pin-compatible successor exists because the TAJ series is the current mainstream molded tantalum family; the C case size (6.00 mm x 3.20 mm x 2.80 mm) is a standard JEDEC footprint shared with other vendors, so a second-source cross is straightforward if needed.