KEMET is one of the few passive-component manufacturers that covers almost every capacitor technology under one roof — tantalum, multilayer ceramic (MLCC), aluminum electrolytic, film, polymer electrolytic and supercapacitors — and extends into inductors, EMI filtering and sensors. After joining the YAGEO group in 2020, it operates as "KEMET – A YAGEO Company", offering multiple reliability grades for the same technology family: commercial, automotive (AEC-Q200), COTS, military (MIL-PRF) and space. That is exactly its core value proposition: one requirement, several technology routes to choose from.
This article walks through the KEMET product family map, then drills into 22 popular part numbers that are frequently quoted in power supply designs — 18 standard tantalum parts (T491 series), 3 polymer tantalum parts (T520/T521 series) and 1 MLCC.
Tantalum Capacitors (MnO₂ solid tantalum) Representative series include T491 (industrial/automotive), T492 (military, CWR11 style per MIL-PRF-55365/8), T493/T494/T495 (low-ESR / COTS grades) and T498 (150°C automotive option). Key strengths: high reliability, wide temperature range (−55°C to +125°C) and low leakage current. Typical roles: power filtering, decoupling and energy storage.
Polymer Tantalum Capacitors (KO-CAP) Representative series: T520/T521 (general-purpose low ESR) and T530/T550 (ultra-low ESR, below 10mΩ). The conductive polymer cathode replaces MnO₂, delivering milliohm-level ESR, excellent capacitance retention at high frequencies and high ripple current capability — ideal for DC-DC output decoupling and high-frequency, high-current rails.
Multilayer Ceramic Capacitors (MLCC) Covers C0G, X7R, X5R dielectrics, plus high-voltage, automotive AEC-Q200, Open Mode and Flexible termination variants. Highest volumetric efficiency; used for high-frequency bypassing, resonant circuits and decoupling.
Aluminum Electrolytic / Aluminum Polymer Standard electrolytic, hybrid, snap-in and AO-CAP (aluminum polymer, e.g. A798). Suited to bulk capacitance, high-voltage bus rails and the input stage of power supplies.
Film Capacitors DC-Link, pulse and safety-certified AutoFilm series for new energy, EV, inverters and isolation applications.
Supercapacitors (ENYCAP) FT / FCS / FS series for backup power, peak power assist and energy harvesting.
Inductors / EMI / Sensors Power inductors, common-mode chokes, EMI filters, current and proximity sensors, and relays — completing the power solution alongside the capacitor portfolio.
All 22 part numbers fall into the three series highlighted above: 18 T491 solid tantalum, 3 T520/T521 polymer tantalum and 1 MLCC, together serving power filtering and decoupling.
T491 is KEMET's highest-volume tantalum series. MnO₂ cathode, high reliability, low leakage, all models listed here are automotive grade, ±10% tolerance and rated to 125°C. The part number is self-documenting: "T491" is the series, the letter (A/B/C/D/X) is the case size (from 3216-18 up to 7343-43), the middle digits encode capacitance and voltage, "K" means ±10%, and "AT" marks the automotive grade. The 18 models:
A few models worth remembering. T491X107K025AT is the lowest-ESR T491 in this list — 100µF/25V at only 0.3Ω — the first choice for 24V/28V rail filtering. T491X476K035AT keeps 47µF at 35V, suitable for higher-voltage bus energy storage. T491D227K010AT and T491D227K016AT reach 220µF, the classic low-voltage bulk capacitors. And T491B107K006AT / T491B476K010AT pack 100µF and 47µF into the compact B case — the best "small footprint, high capacitance" options.
KO-CAP replaces the MnO₂ cathode with a conductive polymer, achieving extremely low ESR and excellent high-frequency capacitance retention — without the "thermal-runaway burn-out" failure mode of MnO₂ parts. One number says it all: for the same 100µF/6.3V rating, the T491 sits at 3Ω (3000mΩ) while the T520 is at 40mΩ — a 75× difference. The three models:
The suffix is a shortcut: ATE040 means 40mΩ, ATE025 means 25mΩ — you can read the impedance level straight off the part number. The rule of thumb: choose T491 for general filtering, T520/T521 for low impedance, high ripple current and DC-DC output decoupling.
This is a KEMET X7R ceramic capacitor: 100nF (0.1µF)/50V, 0603 package, ±10% tolerance, 125°C rating. It forms the classic "tantalum + ceramic" pairing: the tantalum part handles bulk storage and filtering, the MLCC handles high-frequency bypassing, and together they suppress ripple across a wide frequency band.
For small-package general filtering, start with the A/B-case T491 parts: T491A106K016AT, T491A106K010AT, T491B106K016AT, T491B106K020AT. For small footprint with high capacitance, choose T491B476K010AT and T491B107K006AT. For high-voltage rails (35V/50V), lock onto T491D106K035AT, T491D106K050AT and T491X476K035AT. For low-voltage high-capacitance bulk, use T491D227K010AT and T491D227K016AT. For ultra-low ESR and DC-DC output decoupling, go with T520B107M006ATE040, T520V337M2R5ATE025 and T521D107M025ATE040, and keep C0603C104K5RACTU as the high-frequency bypass companion.
KEMET's real value is "one requirement, multiple technology routes": MnO₂ solid tantalum (T491) for high reliability and wide temperature, polymer KO-CAP (T520/T521) for ultra-low impedance, MLCC for high-density high-frequency bypass — with military and space grades available up the ladder, so a single BOM need can be upgraded smoothly within the series. All 22 models above are available in genuine stock with stable supply channels at ICGOODFIND (#ICGOODFIND), supporting small-batch samples, full-reel supply, spec verification, alternate-part recommendations and one-stop BOM consolidation. Just send the part number to lock in stock and pricing.
