T491C225M025AS Equivalent & Substitute Parts

Part Overview

The T491C225M025AS is a 2.2 µF molded tantalum capacitor manufactured by KEMET, rated for 25 V with ±20% tolerance and 3.5 Ohm equivalent series resistance (ESR). This component operates across the temperature range of -55°C to 125°C and is housed in a 2312 (6032 Metric) surface mount package. The part is classified as obsolete, necessitating identification of active equivalent and substitute components for ongoing design requirements and procurement needs.

Key Parameters

Parameter	Value
Capacitance	2.2 µF
Voltage Rating	25 V
Tolerance	±20%
Type	Molded Tantalum
ESR (Equivalent Series Resistance)	3.5 Ohm
Operating Temperature Range	-55°C to 125°C
Package / Case	2312 (6032 Metric)
Mounting Type	Surface Mount
Physical Dimensions	0.236" L x 0.126" W (6.00mm x 3.20mm)
Height - Seated (Max)	0.110" (2.80mm)
Moisture Sensitivity Level (MSL)	1 (Unlimited)
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution of the T491C225M025AS is determined by strict adherence to the following electrical and mechanical parameters:

Primary Substitution Criteria:

Capacitance: 2.2 µF (exact match required)
Voltage Rating: 25 V minimum (equal or higher voltage ratings are acceptable)
Tolerance: ±20% or tighter (±10% tolerance is acceptable as an upgrade)
ESR: 3.5 Ohm (equivalent or lower ESR acceptable)
Package / Case: 2312 (6032 Metric) (exact match required)
Mounting Type: Surface Mount (exact match required)
Operating Temperature Range: -55°C to 125°C minimum (extended ranges acceptable)
Type: Molded Tantalum (exact match required)

Substitution Categories:

Direct Substitutes (Same Electrical Specifications): Parts with identical capacitance, voltage rating, tolerance, and ESR specifications. These components are interchangeable without circuit redesign.

Upgrade Substitutes (Enhanced Specifications): Parts with improved tolerance (±10% vs. ±20%), higher voltage ratings (35 V vs. 25 V), or extended operating temperature ranges. These provide enhanced performance margins and are electrically compatible.

Cross-Manufacturer Substitutes: Components from alternative manufacturers (KYOCERA AVX, Vishay Sprague) meeting identical electrical and mechanical specifications, enabling supply chain flexibility.

Parameter Comparison

Part Number	Manufacturer	Capacitance	Voltage	Tolerance	ESR	Temp Range	Package	Status	RoHS
T491C225M025AS	KEMET	2.2 µF	25 V	±20%	3.5 Ohm	-55°C to 125°C	2312	Obsolete	ROHS3
T491C225M025AT	KEMET	2.2 µF	25 V	±20%	3.5 Ohm	-55°C to 125°C	2312	Active	ROHS3
T491C225K025AT	KEMET	2.2 µF	25 V	±10%	3.5 Ohm	-55°C to 125°C	2312	Active	ROHS3
T491C225K035AH	KEMET	2.2 µF	35 V	±10%	3.5 Ohm	-55°C to 125°C	2312	Active	RoHS NC
T491C225K035AT	KEMET	2.2 µF	35 V	±10%	3.5 Ohm	-55°C to 125°C	2312	Active	ROHS3
T491C225M035AT	KEMET	2.2 µF	35 V	±20%	3.5 Ohm	-55°C to 125°C	2312	Active	ROHS3
T499C225K035ATE3K5	KEMET	2.2 µF	35 V	±10%	3.5 Ohm	-55°C to 175°C	2312	Active	ROHS3
TAJC225K035H	KYOCERA AVX	2.2 µF	35 V	±10%	3.5 Ohm	-55°C to 125°C	2312	Active	RoHS NC
TAJC225K035RNJ	KYOCERA AVX	2.2 µF	35 V	±10%	3.5 Ohm	-55°C to 125°C	2312	Active	ROHS3
TAJC225M035RNJ	KYOCERA AVX	2.2 µF	35 V	±20%	3.5 Ohm	-55°C to 125°C	2312	Active	ROHS3
293D225X0025C2TE3	Vishay Sprague	2.2 µF	25 V	±20%	3.2 Ohm	-55°C to 125°C	2312	Active	ROHS3

Engineering Selection Recommendations

Direct Replacement (Same Specifications):

T491C225M025AT is the primary direct replacement for T491C225M025AS. Both components share identical electrical specifications (2.2 µF, 25 V, ±20% tolerance, 3.5 Ohm ESR) and mechanical packaging. The T491C225M025AT is active in production with ROHS3 compliance, providing continuity for existing designs without circuit modification.

Upgrade Path (Enhanced Tolerance):

T491C225K025AT provides improved tolerance performance (±10% vs. ±20%) while maintaining all other specifications identical to the original part. This upgrade is suitable for applications requiring tighter capacitance control. The component is active and ROHS3 compliant.

Voltage Margin Enhancement:

T491C225K035AT and T491C225M035AT offer 35 V voltage ratings compared to the original 25 V specification. These upgrades provide increased voltage margin and are recommended for applications subject to voltage transients or requiring design safety margins. Both are active and ROHS3 compliant. T491C225K035AT combines 35 V rating with ±10% tolerance for maximum performance enhancement.

Extended Temperature Operation:

T499C225K035ATE3K5 extends the operating temperature range to -55°C to 175°C while maintaining 2.2 µF capacitance, 35 V rating, and ±10% tolerance. This component is designated for automotive applications (AEC-Q200 rated) and is active with ROHS3 compliance.

Cross-Manufacturer Alternatives:

TAJC225K035RNJ (KYOCERA AVX) and TAJC225M035RNJ (KYOCERA AVX) provide equivalent electrical specifications to KEMET components with identical package dimensions. TAJC225K035RNJ is ROHS3 compliant with ±10% tolerance and 35 V rating. TAJC225M035RNJ offers ±20% tolerance at 35 V. These alternatives enable supply chain diversification.

Similar Specification Alternative:

293D225X0025C2TE3 (Vishay Sprague) matches the original part's 2.2 µF, 25 V, ±20% specifications with marginally lower ESR (3.2 Ohm vs. 3.5 Ohm). This component is active and ROHS3 compliant, providing an alternative source for equivalent performance.

Compliance Considerations:

Components designated as RoHS non-compliant (T491C225K035AH, TAJC225K035H) are suitable only for applications where RoHS compliance is not required. For RoHS3-compliant designs, select from the ROHS3-designated alternatives.

Frequently Asked Questions (FAQ)

Q: Can T491C225M025AT directly replace T491C225M025AS without circuit modification?

A: Yes. T491C225M025AT is a direct equivalent with identical capacitance (2.2 µF), voltage rating (25 V), tolerance (±20%), ESR (3.5 Ohm), and package (2312). The only difference is product status (active vs. obsolete) and packaging format. No circuit redesign is required.

Q: What is the difference between ±20% and ±10% tolerance specifications?

A: Tolerance defines the allowable deviation of actual capacitance from the nominal value. ±20% tolerance permits capacitance variation between 1.76 µF and 2.64 µF. ±10% tolerance restricts variation to 1.98 µF and 2.42 µF. Applications requiring tighter capacitance control should specify ±10% tolerance parts.

Q: Can a 35 V rated capacitor replace a 25 V rated capacitor?

A: Yes, within the constraints of physical space and circuit requirements. A 35 V rated capacitor is electrically compatible with a 25 V circuit and provides additional voltage margin. However, verify that the component physically fits the PCB layout, as some 35 V variants may have different dimensions.

Q: What does RoHS3 compliance mean?

A: ROHS3 (Restriction of Hazardous Substances Directive 3) compliance indicates the component meets European Union regulations restricting the use of specific hazardous materials including lead, cadmium, mercury, and certain brominated flame retardants. ROHS3-compliant components are required for most commercial and industrial applications in regulated markets.

Q: Are KEMET T491 series and KYOCERA AVX TAJ series components interchangeable?

A: Yes, when electrical specifications (capacitance, voltage, tolerance, ESR) and mechanical packaging (2312 case) are identical. Both manufacturers produce molded tantalum capacitors to industry standards. Cross-manufacturer substitution is valid for equivalent specifications. Verify RoHS compliance status for your application requirements.

Q: What is ESR and why does it matter?

A: Equivalent Series Resistance (ESR) represents the internal resistance of the capacitor, measured in ohms. Lower ESR indicates better high-frequency performance and reduced heat generation. The original part specifies 3.5 Ohm ESR. Substitute parts with equal or lower ESR are acceptable. The Vishay 293D225X0025C2TE3 offers 3.2 Ohm ESR, providing marginal improvement.

Q: Can T499C225K035ATE3K5 be used in non-automotive applications?

A: Yes. T499C225K035ATE3K5 is an automotive-grade component (AEC-Q200 rated) with extended temperature range (-55°C to 175°C). It is suitable for any application requiring these specifications, including industrial and commercial designs. Automotive qualification indicates enhanced reliability testing and is not restrictive for other applications.

Q: What packaging options are available for these substitutes?

A: Packaging formats include Tape & Reel (TR) for automated assembly, Cut Tape (CT) for manual or semi-automated processes, and Digi-Reel® (proprietary format). T491C225M025AT is available in Tape & Reel format. T491C225K035AT is available in Cut Tape & Digi-Reel format. Select packaging based on assembly process requirements.

Q: Is the 2312 package dimension consistent across all substitute parts?

A: Yes. All substitute parts listed use the 2312 (6032 Metric) package with identical dimensions: 0.236" L x 0.126" W (6.00mm x 3.20mm) and maximum seated height of 0.110" (2.80mm). Physical interchangeability is confirmed for PCB layout purposes.

Q: What is Moisture Sensitivity Level (MSL) 1?

A: MSL 1 indicates unlimited shelf life without moisture exposure controls. Components rated MSL 1 do not require special desiccant packaging or baking procedures prior to soldering. All listed substitute parts are MSL 1 rated, matching the original component's moisture handling requirements.

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