Equivalent & Substitute Parts for T491B475K020AS

Part Overview

The T491B475K020AS is a 4.7 µF molded tantalum capacitor rated at 20 V with ±10% tolerance, manufactured by KEMET in the 1411 (3528 Metric) package. This component is classified as obsolete, indicating discontinuation from the manufacturer. Identification of equivalent and substitute parts is necessary to maintain design continuity, ensure supply chain availability, and support ongoing production or repair requirements for applications utilizing this capacitor specification.

Key Parameters

Parameter	Value	Significance for Substitution
Capacitance	4.7 µF	Must match exactly
Voltage Rating	20 V	Must match or exceed
Tolerance	±10%	Must match or be tighter
Package / Case	1411 (3528 Metric)	Must match for PCB compatibility
ESR (Equivalent Series Resistance)	3 Ohm	Must match or be lower
Operating Temperature Range	-55°C ~ 125°C	Must meet or exceed
Mounting Type	Surface Mount	Must match
Type	Molded Tantalum	Must match

Substitute Part Grouping Explanation

Substitution logic for the T491B475K020AS is determined by strict adherence to the following electrical and mechanical parameters:

Primary Substitution Criteria:

Capacitance: 4.7 µF (exact match required)
Voltage Rating: 20 V minimum (higher ratings acceptable as upgrades)
Tolerance: ±10% (tighter tolerances acceptable)
Package: 1411 (3528 Metric) (exact match required for PCB fit)
Mounting Type: Surface Mount (exact match required)
Type: Molded Tantalum (exact match required)

Secondary Compatibility Parameters:

ESR: 3 Ohm or lower (lower values acceptable)
Operating Temperature: -55°C ~ 125°C minimum (extended ranges acceptable)
Size/Dimension: 0.138" L x 0.110" W (3.50mm x 2.80mm) (exact match required)
Height - Seated (Max): 0.083" (2.10mm) (exact match required)

Substitute parts are grouped into three categories based on their relationship to the main part:

Direct Equivalents: Parts with identical electrical specifications and active product status.

Upgrade Substitutes: Parts with identical capacitance and voltage rating but enhanced operating temperature range or improved ESR characteristics.

Alternative Substitutes: Parts meeting all primary criteria with minor variations in secondary parameters or different manufacturer series designation.

Parameter Comparison

Part Number	Manufacturer	Capacitance	Voltage Rating	Tolerance	ESR (Ohm)	Operating Temp. Range	Product Status	RoHS Status
T491B475K020AS	KEMET	4.7 µF	20 V	±10%	3.0	-55°C ~ 125°C	Obsolete	Non-compliant
T491B475K020AT	KEMET	4.7 µF	20 V	±10%	3.0	-55°C ~ 125°C	Active	ROHS3 Compliant
TAJB475K020H	KYOCERA AVX	4.7 µF	20 V	±10%	3.0	-55°C ~ 125°C	Active	Non-compliant
TH3B475K020F2900	Vishay Sprague	4.7 µF	20 V	±10%	2.9	-55°C ~ 150°C	Active	Non-compliant
TH3B475K020E2900	Vishay Sprague	4.7 µF	20 V	±10%	2.9	-55°C ~ 150°C	Active	Non-compliant
293D475X9020B2TE3	Vishay Sprague	4.7 µF	20 V	±10%	2.9	-55°C ~ 125°C	Active	ROHS3 Compliant
TH3B475K035E3100	Vishay Sprague	4.7 µF	35 V	±10%	3.1	-55°C ~ 150°C	Active	Non-compliant
TH3B475K035F3100	Vishay Sprague	4.7 µF	35 V	±10%	3.1	-55°C ~ 150°C	Active	Non-compliant

Engineering Selection Recommendations

For Direct Replacement (Identical Specifications):

T491B475K020AT (KEMET) is the primary direct replacement for the obsolete T491B475K020AS. Both parts share identical electrical parameters: 4.7 µF capacitance, 20 V voltage rating, ±10% tolerance, 3.0 Ohm ESR, and -55°C ~ 125°C operating temperature range. The T491B475K020AT is active in production and ROHS3 compliant, providing improved regulatory compliance over the original part. Packaging is identical (1411/3528 Metric), ensuring direct PCB compatibility without layout modifications.

For Enhanced Performance (Upgraded Specifications):

TH3B475K020E2900 and TH3B475K020F2900 (Vishay Sprague, TANTAMOUNT™ series) provide electrical equivalence with performance enhancements. Both maintain 4.7 µF capacitance and 20 V rating but offer reduced ESR (2.9 Ohm versus 3.0 Ohm) and extended operating temperature range (-55°C ~ 150°C versus -55°C ~ 125°C). These parts are AEC-Q200 rated for automotive applications. Package and mounting specifications remain identical to the original part.

For Voltage Margin Applications (Upgraded Voltage Rating):

TH3B475K035E3100 and TH3B475K035F3100 (Vishay Sprague, TANTAMOUNT™ series) provide 35 V voltage rating while maintaining 4.7 µF capacitance and ±10% tolerance. These parts are suitable for applications requiring additional voltage margin or operating in higher voltage environments. Extended operating temperature range (-55°C ~ 150°C) and AEC-Q200 automotive rating are included. ESR is 3.1 Ohm, slightly higher than the original specification.

For RoHS Compliance:

293D475X9020B2TE3 (Vishay Sprague, TANTAMOUNT™ 293D series) is ROHS3 compliant and maintains all primary electrical specifications: 4.7 µF, 20 V, ±10% tolerance, 2.9 Ohm ESR. Operating temperature range matches the original (-55°C ~ 125°C). This part is suitable for applications with RoHS compliance requirements.

For Cross-Manufacturer Compatibility:

TAJB475K020H (KYOCERA AVX, TAJ series) provides equivalent specifications with alternative manufacturer sourcing. All electrical parameters match the original part exactly. This option supports supply chain diversification and reduces single-source dependency.

Frequently Asked Questions (FAQ)

Q: Can T491B475K020AT be used as a direct replacement for T491B475K020AS?

A: Yes. T491B475K020AT is a direct equivalent with identical capacitance (4.7 µF), voltage rating (20 V), tolerance (±10%), ESR (3.0 Ohm), operating temperature range (-55°C ~ 125°C), and package (1411/3528 Metric). The primary difference is product status: T491B475K020AT is active and ROHS3 compliant, while T491B475K020AS is obsolete and non-compliant.

Q: What is the difference between the 20 V and 35 V rated parts?

A: The 35 V rated parts (TH3B475K035E3100, TH3B475K035F3100) provide higher voltage margin for the same 4.7 µF capacitance. These are suitable for applications requiring additional voltage headroom or operating in higher voltage circuits. All other specifications remain compatible with the original 20 V part. Selection depends on circuit voltage requirements.

Q: Are the Vishay Sprague TH3 series parts compatible with the KEMET T491 series?

A: Yes, for applications where electrical specifications are the primary requirement. Both series use identical 1411 (3528 Metric) packaging and share the same capacitance, voltage rating, tolerance, and operating temperature range. The TH3 series offers lower ESR (2.9 Ohm) and extended temperature range (-55°C ~ 150°C) with AEC-Q200 automotive rating. PCB footprint compatibility is maintained.

Q: What does ESR (Equivalent Series Resistance) mean for capacitor selection?

A: ESR is the internal resistance of the capacitor, measured in Ohms. Lower ESR values indicate better high-frequency performance and reduced heat generation. The original T491B475K020AS has 3.0 Ohm ESR. Substitute parts with 2.9 Ohm ESR (Vishay Sprague TH3 and 293D series) provide marginal improvement. Parts with 3.1 Ohm ESR (35 V rated Vishay Sprague parts) are slightly higher but remain within acceptable tolerance for most applications.

Q: Is RoHS compliance important for my application?

A: RoHS compliance is mandatory for products sold in the European Union and many other markets. T491B475K020AT and 293D475X9020B2TE3 are ROHS3 compliant. If your application or end market requires RoHS compliance, select from these options. Non-compliant parts may be restricted from certain markets or applications.

Q: Can I use a higher voltage rated capacitor (35 V) in place of a 20 V part?

A: Yes. Higher voltage ratings are acceptable substitutes for lower voltage applications. A 35 V capacitor can be used in a 20 V circuit without electrical issues. However, verify that physical dimensions and package compatibility remain unchanged. The 35 V Vishay Sprague parts maintain identical 1411 (3528 Metric) packaging, so PCB compatibility is preserved.

Q: What is the difference between Tape & Reel (TR) and other packaging options?

A: Tape & Reel packaging is standard for automated assembly processes and high-volume production. The T491B475K020AS is listed without specific packaging designation, while T491B475K020AT, TH3 series, and 293D series are available in Tape & Reel format. For manual assembly or low-volume applications, packaging format may not affect functionality, only handling and storage procedures.

Q: Are all substitute parts available in the same physical dimensions?

A: Yes. All substitute parts listed maintain the same 1411 (3528 Metric) package specification with dimensions of 0.138" L x 0.110" W (3.50mm x 2.80mm) and maximum seated height of 0.083" (2.10mm). This ensures direct PCB footprint compatibility without layout modifications. The 293D475X9020B2TE3 has a maximum seated height of 0.083" (2.11mm), which is within acceptable tolerance for standard PCB assembly.

Q: What is AEC-Q200 rating and why does it matter?

A: AEC-Q200 is an automotive qualification standard for discrete semiconductors and passive components. Parts with this rating (Vishay Sprague TH3 series) have undergone rigorous testing for automotive applications, including temperature cycling, vibration, and reliability testing. If your application is automotive or requires automotive-grade reliability, select AEC-Q200 rated parts.

Q: Can I mix different manufacturers' parts in the same circuit?

A: Yes. All listed substitute parts meet the same electrical specifications and package requirements. Mixing manufacturers (KEMET, KYOCERA AVX, Vishay Sprague) is acceptable from an electrical standpoint. However, verify that procurement, quality assurance, and supply chain procedures support multi-source components if required by your organization.

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