AVX TAJ Part Number Guide: How to Read a Tantalum Part Number

A tantalum part number is not an arbitrary string. Every character encodes a specification, and being able to read it lets you check a quote, spot a wrong listing, or find a substitute in seconds. This guide decodes the AVX TAJ series — the standard, general-purpose moulded tantalum chip — field by field.

The structure

A TAJ part number is built from seven fields:

Field	Meaning	Example
TAJ	Series: standard tantalum chip	TAJ
Case size	Single letter — footprint and height	V
Capacitance code	Three digits, picofarad code	226
Tolerance	Single letter	K
Rated DC voltage	Three digits	050
Packaging	Single letter	R
Specification suffix	Letters, manufacturer-defined	NJ

So TAJV226K050RNJ reads as: standard TAJ series, case V, 22 µF, ±10 %, 50 V, lead-free 7 inch reel, standard suffix.

Capacitance code: the field people get wrong

The three-digit code is the same convention used across the passive industry. The first two digits are the significant figures, and the third digit is the number of zeros to follow — the result is in picofarads.

Code	Calculation	Capacitance
105	10 × 10⁵ pF	1 µF
155	15 × 10⁵ pF	1.5 µF
225	22 × 10⁵ pF	2.2 µF
335	33 × 10⁵ pF	3.3 µF
475	47 × 10⁵ pF	4.7 µF
685	68 × 10⁵ pF	6.8 µF
106	10 × 10⁶ pF	10 µF
226	22 × 10⁶ pF	22 µF
476	47 × 10⁶ pF	47 µF
107	10 × 10⁷ pF	100 µF
157	15 × 10⁷ pF	150 µF

The classic mistake: reading 475 as "47 µF". It is 4.7 µF — the last digit is a multiplier, not part of the value. Likewise 155 is 1.5 µF, not 15 µF, and 685 is 6.8 µF, not 68 µF.

Tolerance code

K = ±10 %
M = ±20 %

Rated DC voltage code

Code	Voltage
002	2.5 V
004	4 V
006	6.3 V
010	10 V
016	16 V
020	20 V
025	25 V
035	35 V
050	50 V

Note that 006 means 6.3 V, not 6 V — a common source of confusion when comparing against a 6.3 V rail.

Case size code

The letter after TAJ defines the physical body. The principal TAJ case sizes are:

Code	EIA code	Length (mm)	Width (mm)	Height (mm)
A	1206	3.20	1.60	1.60
B	1210	3.50	2.80	1.90
C	2312	6.00	3.20	2.60
D	2917	7.30	4.30	2.90
E	2917	7.30	4.30	4.10
V	2924	7.30	6.10	3.45

Note that D and E share the same footprint but differ in height, and that case V is noticeably wider than D — it is not a drop-in replacement. The series also includes a number of smaller and lower-profile case codes (such as R, S, T, P, W, X and Y) for height-limited designs; those must be matched against the datasheet, because the same capacitance and voltage can be offered in several different bodies.

Packaging code

R = lead-free, 7 inch reel
S = lead-free, 13 inch reel
A = gold plating, 7 inch reel
B = gold plating, 13 inch reel

Tin-lead terminations are also available under specific codes but are non-RoHS and typically need to be confirmed with the manufacturer. If your assembly process or compliance requirements care about termination finish or reel size, this single letter is the field that matters.

Specification suffix

NJ is the standard suffix. Additional characters can be appended for special requirements — for example, a dry-pack option on selected codes. Treat the suffix as part of the orderable part number: two parts that differ only in the suffix are not necessarily interchangeable, and dropping the suffix when ordering is a reliable way to receive the wrong goods.

How to sanity-check a tantalum listing

Decode the part number first. The part number is the authoritative specification. If a listing's stated capacitance disagrees with the code, trust the code — and ask the supplier to confirm.
Check the voltage code against your rail. Then apply the derating rule: a 16 V part is not a 16 V application part. See our guide to tantalum capacitors in circuit design for the derating and inrush requirements.
Check the case code against your footprint and height budget. Same footprint does not mean same height.
Check the packaging and suffix fields. They are easy to overlook and expensive to get wrong in volume production.
Verify against the manufacturer's datasheet or an authorised source. Counterfeit and re-marked tantalum is a persistent problem in the open market, and part numbers can be generated that look plausible but do not correspond to any real orderable part. If the construction process behind the part interests you, see how tantalum capacitors are made.

Worked examples

Part number	Case	Capacitance	Tolerance	Voltage
TAJA105K016RNJ	A	1 µF	±10 %	16 V
TAJB335K035RNJ	B	3.3 µF	±10 %	35 V
TAJD107K016RNJ	D	100 µF	±10 %	16 V
TAJV226K050RNJ	V	22 µF	±10 %	50 V

Finding parts

We stock the AVX TAJ range alongside polymer and automotive grades from AVX and Panasonic. Browse the tantalum capacitor range or look up a specific part number directly, for example TAJA105K016RNJ, TAJB335K035RNJ or TAJV226K050RNJ. If you need a cross-reference or a quote on a full BOM, send it through the RFQ form.