T491B686M004ZTAC00 Equivalent & Substitute Parts

Part Overview

The T491B686M004ZTAC00 is a 68 µF molded tantalum capacitor rated at 4 V with ±20% tolerance, manufactured by KEMET in the 1411 (3528 Metric) package. This component is classified as obsolete, indicating discontinuation from the manufacturer. The part features a 1.8 Ohm equivalent series resistance (ESR) and operates across a temperature range of -55°C to 125°C with a rated lifetime of 2000 hours at 125°C. Due to its obsolete status, identification of equivalent and substitute parts is necessary for ongoing design support, maintenance, and production continuity.

Key Parameters

Parameter	Value
Capacitance	68 µF
Voltage Rating	4 V
Tolerance	±20%
Type	Molded Tantalum
ESR (Equivalent Series Resistance)	1.8 Ohm
Package / Case	1411 (3528 Metric)
Size / Dimension	0.138" L x 0.110" W (3.50mm x 2.80mm)
Height - Seated (Max)	0.083" (2.10mm)
Operating Temperature Range	-55°C to 125°C
Lifetime @ Temp.	2000 Hrs @ 125°C
Mounting Type	Surface Mount
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution of the T491B686M004ZTAC00 is determined by strict equivalence across the following critical parameters:

Primary Substitution Criteria:

Capacitance: 68 µF (exact match required)
Voltage Rating: 4 V (exact match required)
Package / Case: 1411 (3528 Metric) (exact match required)
Mounting Type: Surface Mount (exact match required)
Operating Temperature Range: -55°C to 125°C (exact match required)

Secondary Compatibility Parameters:

Tolerance: ±20% (primary specification) or ±10% (tighter tolerance acceptable)
ESR: 1.8 Ohm nominal (1.5 Ohm to 1.8 Ohm acceptable range)
Height - Seated (Max): 0.083" (2.10mm) or lower (space-constrained applications)
RoHS Compliance: ROHS3 or RoHS Compliant (regulatory requirement)
MSL: 1 (Unlimited) (handling and storage requirement)

Substitute parts are grouped into three categories based on these parameters: direct manufacturer equivalents (identical specifications with different packaging or status), direct substitutes (same electrical characteristics with active product status), and parametric equivalents (tighter tolerance or improved ESR characteristics).

Parameter Comparison

Part Number	Manufacturer	Capacitance	Tolerance	Voltage	ESR	Package	Height (Max)	Status	Inventory
T491B686M004ZTAC00	KEMET	68 µF	±20%	4 V	1.8 Ohm	1411 (3528 Metric)	0.083" (2.10mm)	Obsolete	847 Pcs
T491B686M004AT	KEMET	68 µF	±20%	4 V	1.8 Ohm	1411 (3528 Metric)	0.083" (2.10mm)	Active	747 Pcs
T495T686M004ATE1K5	KEMET	68 µF	±20%	4 V	1.5 Ohm @ 100kHz	1411 (3528 Metric)	0.047" (1.20mm)	Active	1097 Pcs
T491B686K004AT	KEMET	68 µF	±10%	4 V	1.8 Ohm	1411 (3528 Metric)	0.083" (2.10mm)	Active	1010 Pcs
T491B686K004AT4153	KEMET	68 µF	±10%	4 V	1.8 Ohm	1411 (3528 Metric)	0.083" (2.10mm)	Active	668 Pcs
T491B686K004AT7280	KEMET	68 µF	±10%	4 V	1.8 Ohm	1411 (3528 Metric)	0.083" (2.10mm)	Active	739 Pcs
T491B686M004AT4153	KEMET	68 µF	±20%	4 V	1.8 Ohm	1411 (3528 Metric)	0.083" (2.10mm)	Active	869 Pcs
TCKOG686BT	Cal-Chip Electronics, Inc.	68 µF	±10%	4 V	1.7 Ohm	1411 (3528 Metric)	0.083" (2.10mm)	Active	56813 Pcs
TCMOG686BT	Cal-Chip Electronics, Inc.	68 µF	±20%	4 V	1.7 Ohm	1411 (3528 Metric)	0.083" (2.10mm)	Active	56753 Pcs

Engineering Selection Recommendations

Direct Manufacturer Equivalent (Recommended Primary Substitute):

T491B686M004AT is the direct active equivalent to the obsolete T491B686M004ZTAC00. Both parts share identical electrical specifications (68 µF, ±20%, 4 V, 1.8 Ohm ESR) and mechanical dimensions. The primary difference is product status: T491B686M004AT is active and available in Tape & Reel packaging. This part is ROHS3 compliant and REACH unaffected, meeting current regulatory requirements. With 747 units in stock, this represents the most direct replacement path.

Alternative KEMET Options with Enhanced Specifications:

T495T686M004ATE1K5 offers improved ESR performance (1.5 Ohm @ 100kHz) and reduced height (0.047" vs. 0.083"), making it suitable for space-constrained applications. This T495 series part maintains all other critical parameters and is active with 1097 units available. The lower profile may require PCB layout verification for height-sensitive designs.

Parametric Equivalents with Tighter Tolerance:

T491B686K004AT, T491B686K004AT4153, and T491B686K004AT7280 provide ±10% tolerance versus the original ±20%, offering improved capacitance accuracy. These parts maintain identical ESR (1.8 Ohm) and dimensions. All three are active KEMET products with combined inventory exceeding 2400 units. Selection among these three variants depends on specific procurement channel or reel configuration requirements.

Cross-Manufacturer Alternatives:

TCKOG686BT (±10% tolerance) and TCMOG686BT (±20% tolerance) from Cal-Chip Electronics, Inc. provide functionally equivalent substitutes with marginally lower ESR (1.7 Ohm). Both are RoHS compliant and REACH unaffected. Significantly higher inventory levels (56813 and 56753 units respectively) indicate strong availability. These parts are suitable for applications where cross-manufacturer sourcing is acceptable.

Frequently Asked Questions (FAQ)

Q: Can T491B686K004AT (±10% tolerance) replace T491B686M004ZTAC00 (±20% tolerance)?

A: Yes. The ±10% tolerance specification is tighter than the original ±20%, meaning the capacitance will be held to a narrower range. This represents an improvement in specification compliance and is electrically compatible with designs accepting ±20% tolerance.

Q: What is the difference between T491B686M004AT and T491B686M004AT4153?

A: Both parts are electrically and mechanically identical (68 µF, ±20%, 4 V, 1.8 Ohm, 1411 package). The suffix "4153" indicates a different reel configuration or procurement lot identifier. Selection depends on packaging requirements for your assembly process.

Q: Is T495T686M004ATE1K5 suitable as a direct replacement?

A: T495T686M004ATE1K5 is electrically compatible (68 µF, ±20%, 4 V) with improved ESR (1.5 Ohm) and reduced height (0.047" vs. 0.083"). The lower profile requires verification that PCB clearance and component placement accommodate the reduced height. The improved ESR may benefit high-frequency applications.

Q: Can I use TCKOG686BT or TCMOG686BT from Cal-Chip Electronics?

A: Yes. Both Cal-Chip parts meet all critical electrical and mechanical parameters (68 µF, 4 V, 1411 package, -55°C to 125°C). TCKOG686BT offers ±10% tolerance; TCMOG686BT offers ±20% tolerance. Both are RoHS compliant. Cross-manufacturer substitution is valid when supply chain flexibility is required.

Q: What does "Tape & Reel (TR)" packaging mean?

A: Tape & Reel packaging indicates the components are supplied on continuous carrier tape wound on a reel, suitable for automated pick-and-place assembly equipment. This is standard for high-volume surface mount production. Verify your assembly equipment compatibility with this packaging format.

Q: Are all substitute parts ROHS3 compliant?

A: KEMET parts (T491 and T495 series) are ROHS3 compliant. Cal-Chip parts (TCKOG686BT and TCMOG686BT) are RoHS compliant. Both certifications meet current regulatory requirements. Verify your specific application's compliance requirements.

Q: What does MSL 1 (Unlimited) mean?

A: Moisture Sensitivity Level 1 (Unlimited) indicates the component has no moisture sensitivity restrictions. These parts do not require special dry-pack storage or baking procedures prior to soldering, simplifying handling and storage logistics.

Request Quote (Ships tomorrow)

Part Number

Quantity

Company

Contact Name

E-mail

Message