T491D156M020ZT Equivalent & Substitute Parts

Part Overview

The T491D156M020ZT is a 15 µF molded tantalum capacitor manufactured by KEMET, rated for 20 V operation in a 2917 (7343 Metric) surface mount package. This component is classified as obsolete product status. Identification of equivalent and substitute parts is necessary to maintain design continuity and ensure procurement availability for applications requiring this capacitance, voltage, and package specification.

Key Parameters

Parameter	Value
Capacitance	15 µF
Voltage Rating	20 V
Tolerance	±20%
Package / Case	2917 (7343 Metric)
Type	Molded Tantalum
ESR	1 Ohm
Operating Temperature Range	-55°C to 125°C
Lifetime @ 125°C	2000 Hrs
Mounting Type	Surface Mount
Moisture Sensitivity Level	1 (Unlimited)

Substitute Part Grouping Explanation

Substitute parts for the T491D156M020ZT are grouped based on the following critical parameters that determine functional equivalence:

Primary Substitution Criteria:

Capacitance: 15 µF (exact match required)
Voltage Rating: 20 V (exact match required)
Package / Case: 2917 (7343 Metric) (exact match required)
Type: Molded Tantalum (exact match required)
Operating Temperature Range: -55°C to 125°C (exact match required)
Lifetime @ 125°C: 2000 Hrs (exact match required)
Mounting Type: Surface Mount (exact match required)
Moisture Sensitivity Level: 1 (Unlimited) (exact match required)

Secondary Substitution Criteria (Allowable Variations):

Tolerance: ±20% or ±10% (tighter tolerance acceptable)
ESR: 1 Ohm or 1.1 Ohm @ 100kHz (minor variation acceptable)
Manufacturer: KEMET or KYOCERA AVX (different manufacturers acceptable)
Product Status: Active preferred over Obsolete
RoHS Compliance: ROHS3 Compliant preferred

Substitutes are classified into two categories: Direct Manufacturer Equivalents (same tolerance and ESR specifications) and Parametric Equivalents (tighter tolerance or minor ESR variation).

Parameter Comparison

Part Number	Manufacturer	Capacitance	Tolerance	Voltage	ESR	Package	Product Status	RoHS Status	Inventory
T491D156M020ZT	KEMET	15 µF	±20%	20 V	1 Ohm	2917	Obsolete	ROHS3 Compliant	708 Pcs
T491D156M020AT	KEMET	15 µF	±20%	20 V	1 Ohm	2917	Active	ROHS3 Compliant	1103 Pcs
T491D156K020AH	KEMET	15 µF	±10%	20 V	1 Ohm	2917	Active	RoHS non-compliant	709 Pcs
T491D156K020AT2478	KEMET	15 µF	±10%	20 V	1 Ohm	2917	Active	ROHS3 Compliant	715 Pcs
T491D156K020AT4081	KEMET	15 µF	±10%	20 V	1 Ohm	2917	Active	ROHS3 Compliant	735 Pcs
T491D156K020AT4153	KEMET	15 µF	±10%	20 V	1 Ohm	2917	Active	ROHS3 Compliant	864 Pcs
T491D156M020AH2478	KEMET	15 µF	±20%	20 V	1 Ohm	2917	Active	RoHS non-compliant	1035 Pcs
T491D156M020AT2478	KEMET	15 µF	±20%	20 V	1 Ohm	2917	Active	ROHS3 Compliant	952 Pcs
T491D156M020AT24787622	KEMET	15 µF	±20%	20 V	1 Ohm	2917	Active	ROHS3 Compliant	993 Pcs
T491D156M020AT7280	KEMET	15 µF	±20%	20 V	1 Ohm	2917	Active	ROHS3 Compliant	1071 Pcs
TAJD156K020HNJ	KYOCERA AVX	15 µF	±10%	20 V	1.1 Ohm @ 100kHz	2917	Active	RoHS non-compliant	643 Pcs

Engineering Selection Recommendations

Direct Manufacturer Equivalent (Recommended Primary Substitutes):

The T491D156M020AT is the direct equivalent to the T491D156M020ZT. Both parts share identical electrical specifications: 15 µF capacitance, ±20% tolerance, 20 V rating, 1 Ohm ESR, and 2917 package. The T491D156M020AT carries Active product status and ROHS3 Compliant certification, providing superior long-term availability compared to the obsolete T491D156M020ZT. Additional KEMET variants with identical specifications include T491D156M020AT2478, T491D156M020AT24787622, and T491D156M020AT7280, which differ only in packaging or internal traceability codes.

Parametric Equivalents with Tighter Tolerance (Secondary Substitutes):

Parts T491D156K020AT2478, T491D156K020AT4081, and T491D156K020AT4153 provide ±10% capacitance tolerance instead of ±20%, with all other electrical parameters identical. These parts are suitable for applications requiring improved capacitance accuracy. All three carry Active product status and ROHS3 Compliant certification.

Alternative Manufacturer Option:

The TAJD156K020HNJ from KYOCERA AVX provides equivalent functionality with ±10% tolerance and 1.1 Ohm ESR @ 100kHz. This part carries Active product status but is RoHS non-compliant. Selection of this part requires confirmation that RoHS non-compliance is acceptable for the application.

Compliance Considerations:

For applications requiring ROHS3 compliance, select from: T491D156M020AT, T491D156M020AT2478, T491D156M020AT24787622, T491D156M020AT7280, T491D156K020AT2478, T491D156K020AT4081, or T491D156K020AT4153.

For applications where RoHS compliance is not required, T491D156M020AH2478 and TAJD156K020HNJ are available alternatives.

Frequently Asked Questions (FAQ)

Q: Can T491D156M020AT be used as a direct replacement for T491D156M020ZT?

A: Yes. Both parts are identical in capacitance (15 µF), tolerance (±20%), voltage rating (20 V), ESR (1 Ohm), package (2917), operating temperature range (-55°C to 125°C), and lifetime specification (2000 Hrs @ 125°C). The primary difference is product status: T491D156M020AT is Active while T491D156M020ZT is Obsolete.

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

A: Tolerance specifies the allowable deviation of actual capacitance from the nominal 15 µF value. ±20% tolerance allows deviation from 12 µF to 18 µF. ±10% tolerance allows deviation from 13.5 µF to 16.5 µF. Parts with ±10% tolerance provide tighter capacitance control and are suitable for applications requiring improved accuracy. All other electrical parameters remain identical between tolerance grades.

Q: Are the different KEMET part number suffixes (2478, 24787622, 7280, 4153, 4081) functionally equivalent?

A: Yes. These suffixes represent internal KEMET traceability, packaging, or manufacturing codes. The electrical specifications, package dimensions, and performance characteristics are identical across all variants. Selection among these parts can be based on inventory availability and packaging preferences.

Q: What does ESR mean and why does TAJD156K020HNJ have 1.1 Ohm instead of 1 Ohm?

A: ESR (Equivalent Series Resistance) represents the internal resistance of the capacitor at a specified frequency. The TAJD156K020HNJ specifies 1.1 Ohm @ 100kHz, while KEMET parts specify 1 Ohm without frequency notation. The 0.1 Ohm difference is minor and acceptable for most applications. Confirmation of ESR requirements at the application's operating frequency is recommended for high-frequency or low-impedance circuits.

Q: Is the 2917 package the same as 7343 Metric?

A: Yes. 2917 is the EIA (Electronics Industries Alliance) designation, and 7343 Metric is the IEC (International Electrotechnical Commission) designation for the same physical package. Both designations refer to identical dimensions: 0.287" L × 0.169" W (7.30 mm × 4.30 mm) with maximum seated height of 0.122" (3.10 mm).

Q: Can I use a part with RoHS non-compliance if my application requires ROHS3 compliance?

A: No. If your application or end-use market requires ROHS3 compliance, only select parts explicitly marked as ROHS3 Compliant. Parts marked as RoHS non-compliant (such as T491D156M020AH2478 and TAJD156K020HNJ) do not meet this requirement and may create regulatory or contractual violations.

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

A: MSL 1 indicates unlimited moisture sensitivity, meaning the component can be stored indefinitely without special moisture control measures. This is the least restrictive moisture sensitivity classification and simplifies handling and storage requirements.

Q: Should I prioritize inventory availability when selecting a substitute?

A: Inventory availability is a practical consideration for procurement timelines. However, electrical and compliance specifications must be the primary selection criteria. Among parts meeting all electrical and compliance requirements, higher inventory levels may reduce lead times.

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