TC502J2K NTC Thermistor 5kΩ Bead - Equivalent & Substitute Parts

Part Overview

The TC502J2K is an NTC thermistor manufactured by Littelfuse, designed for temperature sensing applications requiring a 5kΩ nominal resistance at 25°C. This component features a bead form factor with epoxy encapsulation and free-hanging lead configuration. The product is classified as obsolete, making identification of functionally equivalent alternatives essential for ongoing system support and new design implementations. Substitute parts must maintain electrical compatibility across resistance, tolerance, and thermal response characteristics while meeting current manufacturing and compliance standards.

Key Parameters

Parameter	Value	Significance for Substitution
Resistance @ 25°C	5kΩ	Primary electrical specification; substitute must match nominal value
Resistance Tolerance	±10%	Defines acceptable resistance range; substitute tolerance must be compatible with circuit design margins
B0/50 Value	3892K	Thermal response characteristic; determines temperature coefficient and sensing accuracy
Operating Temperature Range	-55°C to 150°C (substitute); 150°C max (main part)	Defines usable temperature window; substitute must cover or exceed application requirements
Package / Case	Bead, Epoxy	Physical form factor; must be compatible with mounting and thermal coupling requirements
Mounting Type	Free Hanging	Installation method; substitute must support equivalent mounting configuration
RoHS Status	ROHS3 Compliant	Regulatory compliance requirement; substitute must meet equivalent or higher standard

Substitute Part Grouping Explanation

The TC502J2K has been identified with one manufacturer-recommended substitute: TE Connectivity Measurement Specialties part number 701007.

Substitution is valid based on the following electrical and mechanical alignment:

Nominal Resistance: Both parts specify 5kΩ @ 25°C
Thermal Response: B0/50 values are within 0.03% (3892K vs 3891K), ensuring equivalent temperature sensing characteristics
Package Form: Both utilize bead configuration with free-hanging leads, maintaining identical mechanical interface
Compliance: Both parts are ROHS3 compliant and carry EAR99 ECCN classification
Operating Range: The substitute (−55°C to 150°C) extends the lower temperature limit compared to the main part (150°C maximum), providing broader application coverage

The substitute part is manufactured by an established OEM supplier and maintains active product status, ensuring long-term availability and supply chain continuity.

Parameter Comparison

Parameter	TC502J2K (Littelfuse)	701007 (TE Connectivity)	Compatibility Assessment
Resistance @ 25°C	5kΩ	5kΩ	Identical
Resistance Tolerance	±10%	±0.2°C	Substitute tolerance is tighter; compatible
B0/50 Value	3892K	3891K	0.03% variance; functionally equivalent
B25/85 Value	Not specified	3976K	Substitute provides additional thermal data
Operating Temperature	−55°C to 150°C (max 150°C)	−55°C to 150°C	Substitute covers extended range
Lead Length	1.50" (38.00mm)	3.00" (76.20mm)	Substitute has longer leads; verify mechanical fit
Package / Case	Bead, Epoxy	Bead	Compatible form factor
Mounting Type	Free Hanging	Free Hanging	Identical
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	Equivalent compliance
Product Status	Obsolete	Active	Substitute ensures ongoing availability

Engineering Selection Recommendations

The TE Connectivity 701007 is the qualified manufacturer-recommended substitute for the obsolete TC502J2K. Selection is supported by:

Electrical Equivalence: Matching 5kΩ nominal resistance and near-identical B-value thermal response ensure circuit performance parity
Regulatory Compliance: Both parts meet ROHS3 requirements and carry identical ECCN classification, satisfying procurement and export control standards
Supply Continuity: The substitute maintains active manufacturing status, eliminating obsolescence risk associated with the original part
Mechanical Compatibility: Identical bead package and free-hanging configuration preserve PCB layout and thermal coupling characteristics

Lead Length Consideration: The substitute features 3.00" leads compared to the original 1.50" specification. Verify that extended lead length accommodates existing board layout and does not introduce unintended thermal coupling or mechanical stress.

Frequently Asked Questions (FAQ)

Q: Can the 701007 be used as a direct replacement without circuit modification?

A: Yes, for applications where the extended lead length (3.00" vs 1.50") does not create mechanical or thermal interference. The electrical characteristics are equivalent, and both parts are ROHS3 compliant. Verify lead routing and thermal coupling requirements in your specific application.

Q: What is the significance of the B-value difference (3892K vs 3891K)?

A: The 0.03% variance in B0/50 values is negligible for practical temperature sensing applications. Both values define the thermal response curve and will produce equivalent temperature coefficient behavior across the operating range.

Q: Why does the substitute have a tighter resistance tolerance (±0.2°C vs ±10%)?

A: The TE Connectivity part specifies tolerance in temperature units (±0.2°C) rather than percentage, reflecting a more precise manufacturing process. This tighter tolerance is compatible with and does not negatively impact circuits designed for the original ±10% tolerance.

Q: Is the substitute suitable for applications requiring temperatures below 0°C?

A: Yes. The 701007 is rated for −55°C to 150°C, extending the lower temperature limit compared to the TC502J2K specification. Verify that the thermal response characteristics meet your specific sensing requirements across the full operating range.

Q: Are there any compliance or certification differences between the two parts?

A: Both parts are ROHS3 compliant, carry EAR99 ECCN classification, and are subject to identical regulatory frameworks. No additional certifications or compliance actions are required when substituting the 701007 for the TC502J2K.

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