T491B475M025AT4021 Molded Tantalum Capacitor Equivalent & Substitute Parts

Part Overview

The T491B475M025AT4021 is a 4.7 µF molded tantalum capacitor manufactured by KEMET, rated for 25 V operation with ±20% capacitance tolerance. This surface mount component in 1411 (3528 Metric) package is designed for general purpose applications requiring stable capacitance performance across the operating temperature range of -55°C to 125°C. The part is ROHS3 compliant and carries MSL 1 (Unlimited) moisture sensitivity rating, indicating suitability for standard manufacturing environments without special handling requirements.

Equivalent and substitute parts are identified when design requirements permit tolerance relaxation, ESR optimization, or manufacturer substitution while maintaining electrical and mechanical compatibility within the same package footprint and voltage rating.

Substiute Parts

T491B475M025AT4021

KEMETIn Stock: 1174T491B475M025AT4021 Datasheet

Current PartRFQ

T494B475K025AT

KEMETIn Stock: 1686T494B475K025AT Datasheet

Parametric EquivalentRFQ

T495B475K025ATE700

KEMETIn Stock: 2794T495B475K025ATE700 Datasheet

Parametric EquivalentRFQ

TCKIE475BT

Cal-Chip Electronics, Inc.In Stock: 34818TCKIE475BT Datasheet

Parametric EquivalentRFQ

TCMIE475BT

Cal-Chip Electronics, Inc.In Stock: 37085TCMIE475BT Datasheet

Parametric EquivalentRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution logic for the T491B475M025AT4021 is based on the following allowed parameters:

Critical Parameters (Must Match):

• Capacitance: 4.7 µF
• Voltage Rating: 25 V
• Package / Case: 1411 (3528 Metric)
• Mounting Type: Surface Mount
• Component Type: Molded Tantalum Capacitor
• Operating Temperature Range: -55°C ~ 125°C

Flexible Parameters (Substitution Permitted):

• Tolerance: ±20% (tighter tolerance ±10% is acceptable as it represents improved precision)
• ESR: 1.5 Ohm (lower ESR values are acceptable as they represent improved performance)
• Manufacturer: Alternative manufacturers permitted if all critical parameters match

Compliance Parameters (Must Maintain):

• RoHS3 Compliance
• MSL 1 (Unlimited) rating
• Lifetime @ Temp.: 2000 Hrs @ 125°C

Substitute parts are grouped into two categories:

Category A - Direct Equivalents (Same Tolerance ±20%): TCMIE475BT from Cal-Chip Electronics, Inc. matches the original tolerance specification while offering identical electrical and mechanical characteristics.

Category B - Precision Upgrades (Tighter Tolerance ±10%): T494B475K025AT, T495B475K025ATE700, and TCKIE475BT provide ±10% tolerance, representing improved capacitance accuracy. These parts are electrically and mechanically compatible with identical package dimensions and voltage ratings.

Parameter Comparison

Engineering Selection Recommendations

All identified substitute parts maintain full compatibility with the T491B475M025AT4021 across critical electrical and mechanical parameters. Selection among substitutes is determined by application-specific requirements and availability:

For Direct Replacement (Identical Specifications): TCMIE475BT from Cal-Chip Electronics, Inc. provides direct substitution with matching ±20% tolerance and 1.5 Ohm ESR. This part is suitable when the original KEMET part is unavailable and tolerance specifications must remain unchanged. All regulatory compliance certifications (ROHS3, MSL 1, REACH Unaffected) are maintained.

For Improved Performance (Tighter Tolerance): T494B475K025AT, T495B475K025ATE700, and TCKIE475BT offer ±10% capacitance tolerance, providing enhanced precision over the original ±20% specification. These parts are electrically and mechanically interchangeable and suitable for applications where improved capacitance accuracy is beneficial. T495B475K025ATE700 additionally provides reduced ESR (700 mOhm @ 100kHz) compared to the original 1.5 Ohm specification, offering improved high-frequency performance characteristics.

Manufacturer Considerations: KEMET-manufactured substitutes (T494B475K025AT, T495B475K025ATE700) maintain original manufacturer continuity. Cal-Chip Electronics, Inc. substitutes (TCKIE475BT, TCMIE475BT) provide alternative sourcing with equivalent compliance and performance ratings. All parts carry Active product status, ensuring continued availability and manufacturing support.

Compliance Verification: All substitute parts maintain ROHS3 compliance, MSL 1 (Unlimited) moisture sensitivity rating, and 2000 Hrs @ 125°C lifetime specification. No additional qualification or testing is required for substitution within the same application context.

Frequently Asked Questions (FAQ)

Q: Can T494B475K025AT replace T491B475M025AT4021 in my circuit?

A: Yes. T494B475K025AT is electrically and mechanically compatible. Both parts share identical capacitance (4.7 µF), voltage rating (25 V), package dimensions (1411/3528 Metric), and operating temperature range (-55°C ~ 125°C). The primary difference is improved tolerance (±10% versus ±20%), which represents enhanced precision and is acceptable for direct substitution.

Q: What is the difference between T495B475K025ATE700 and the original T491B475M025AT4021?

A: Both parts are identical in capacitance, voltage rating, package, and temperature range. T495B475K025ATE700 offers two improvements: tighter tolerance (±10% versus ±20%) and lower ESR (700 mOhm @ 100kHz versus 1.5 Ohm). Lower ESR reduces impedance at high frequencies, improving circuit performance in applications sensitive to ripple current or transient response.

Q: Are Cal-Chip Electronics parts (TCKIE475BT, TCMIE475BT) equivalent to KEMET parts?

A: Yes, for the specified parameters. Both TCKIE475BT and TCMIE475BT match all critical electrical and mechanical specifications of the T491B475M025AT4021. TCMIE475BT maintains identical ±20% tolerance, while TCKIE475BT provides ±10% tolerance. Both carry ROHS3 compliance and MSL 1 rating. Manufacturer substitution is permitted when original parts are unavailable.

Q: Can I use a substitute part with ±10% tolerance in place of ±20% tolerance specification?

A: Yes. Tighter tolerance (±10%) is a performance improvement over the original ±20% specification. Parts with ±10% tolerance (T494B475K025AT, T495B475K025ATE700, TCKIE475BT) are directly substitutable for applications originally specified with ±20% tolerance. The circuit will experience improved capacitance accuracy.

Q: Do all substitute parts fit the same PCB footprint?

A: Yes. All substitute parts use identical 1411 (3528 Metric) package with dimensions 0.138" L x 0.110" W (3.50mm x 2.80mm) and maximum seated height of 0.083" (2.10mm). No PCB layout modifications are required for substitution.

Q: What is the significance of ESR differences between substitute parts?

A: ESR (Equivalent Series Resistance) affects high-frequency impedance and ripple current handling. The original T491B475M025AT4021 specifies 1.5 Ohm ESR. T494B475K025AT provides 1 Ohm @ 100kHz, and T495B475K025ATE700 provides 700 mOhm @ 100kHz. Lower ESR values reduce impedance at operating frequencies, improving transient response and reducing voltage ripple. Selection depends on circuit requirements for high-frequency performance.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All identified substitute parts (T494B475K025AT, T495B475K025ATE700, TCKIE475BT, TCMIE475BT) carry ROHS3 compliance certification, matching the original T491B475M025AT4021. No compliance issues arise from substitution.

Q: What is MSL 1 (Unlimited) rating and why does it matter?

A: MSL (Moisture Sensitivity Level) 1 (Unlimited) indicates the component requires no special moisture control during storage, handling, or assembly. All substitute parts carry identical MSL 1 rating, eliminating any manufacturing process changes or special bake-out procedures. Standard manufacturing environments are suitable for all parts.

Q: Can I substitute parts from different manufacturers in the same assembly?

A: Yes. KEMET and Cal-Chip Electronics parts are both suitable for use in the same assembly when electrical and mechanical parameters match. All identified substitutes maintain identical package footprints, voltage ratings, capacitance values, and temperature ranges. Manufacturer mixing does not create compatibility issues for this component category.

Q: Which substitute part should I choose if I need the lowest ESR?

A: T495B475K025ATE700 provides the lowest ESR at 700 mOhm @ 100kHz, compared to 1.5 Ohm for the original part and 1 Ohm for T494B475K025AT. This part is suitable for applications requiring optimized high-frequency performance and reduced ripple current characteristics.