KX303J2 Equivalent & Substitute Parts

Part Overview

The KX303J2 is an NTC thermistor manufactured by Littelfuse Inc., designed as a 30kΩ bead-type temperature sensor with epoxy packaging. This component is classified as obsolete, making equivalent substitute parts necessary for ongoing production and maintenance applications. The KX303J2 operates at a maximum of 120°C and dissipates up to 30 mW, serving applications requiring precise temperature measurement in the specified operating range.

Substiute Parts

KX303J2

Littelfuse Inc.In Stock: 1170KX303J2 Datasheet

Current PartRFQ

2152723805

MolexIn Stock: 28462152723805 Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the KX303J2 is determined by the following critical parameters:

• Resistance Value: 30kΩ at 25°C with ±1% tolerance or better
• B-Value Coefficient: 3892K for thermal response matching
• Package Configuration: Bead-type epoxy thermistor
• Operating Temperature Range: Minimum 120°C capability
• Power Dissipation: Minimum 30 mW rating
• Regulatory Compliance: ROHS3 compliance required

The substitute part 2152723805 (Molex) meets these core electrical and mechanical criteria, enabling direct functional replacement in applications where the KX303J2 is no longer available.

Parameter Comparison

Engineering Selection Recommendations

The 2152723805 (Molex) serves as a direct electrical equivalent to the KX303J2 based on matching resistance value, tolerance, and B-value coefficient. Both components maintain ROHS3 compliance, satisfying regulatory requirements for new designs and replacements.

The substitute part features an extended maximum operating temperature of 135°C compared to the KX303J2's 120°C rating, providing additional thermal margin in applications operating near the upper temperature limit.

Physical differences exist in lead wire length (33mm versus 38mm) and mounting configuration (through-hole versus free-hanging). These mechanical variations require verification against specific board layout and assembly requirements before implementation.

Frequently Asked Questions (FAQ)

Q: Can the 2152723805 replace the KX303J2 in all applications?

A: Electrical substitution is valid based on matching 30kΩ resistance, ±1% tolerance, and 3892K B-value. Mechanical compatibility depends on lead wire length tolerance (5mm difference) and mounting method compatibility with your assembly process.

Q: What is the significance of the B-value match?

A: The B-value (3892K) determines the thermistor's thermal response curve. Matching B-values ensure equivalent temperature measurement accuracy across the operating range. Both parts share this specification.

Q: Does the longer operating temperature range of the substitute affect compatibility?

A: No. The 2152723805's 135°C maximum rating exceeds the KX303J2's 120°C requirement, providing additional safety margin without compromising performance in applications limited to 120°C operation.

Q: Are there lead wire length considerations for PCB design?

A: Yes. The 5mm difference in lead wire length (38mm versus 33mm) may affect board layout spacing. Verify that your assembly design accommodates the shorter leads of the 2152723805 or adjust component placement accordingly.

Q: What compliance certifications apply to both parts?

A: Both the KX303J2 and 2152723805 are ROHS3 compliant. The substitute part is REACH Affected, while the original is REACH Unaffected. Verify REACH compliance requirements for your end application and market.