KX503R2 Equivalent & Substitute Parts

Part Overview

The KX503R2 is an NTC thermistor manufactured by Littelfuse Inc., designed as a 50kΩ 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 KX503R2 operates within a maximum temperature range of 120°C and dissipates up to 30mW, serving applications requiring precision temperature measurement in compact form factors.

Substiute Parts

KX503R2

Littelfuse Inc.In Stock: 833KX503R2 Datasheet

Current PartRFQ

192-503QET-A01

Honeywell Sensing and Productivity SolutionsIn Stock: 2155192-503QET-A01 Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the KX503R2 is determined by the following critical parameters:

• Resistance Value: Both parts must maintain 50kΩ nominal resistance at 25°C
• B-Value Characteristics: The B0/50 thermal coefficient must remain within acceptable tolerance for temperature measurement accuracy
• Lead Wire Length: Identical 1.50" (38.00mm) dimension ensures mechanical compatibility
• Operating Temperature Range: The substitute must support the application's thermal requirements
• Package Configuration: Bead-type construction maintains form factor compatibility
• Regulatory Compliance: RoHS and REACH status ensures environmental and supply chain compatibility

The 192-503QET-A01 from Honeywell Sensing and Productivity Solutions meets these substitution criteria with equivalent electrical characteristics and compatible mechanical specifications.

Parameter Comparison

Engineering Selection Recommendations

The 192-503QET-A01 serves as a direct functional equivalent to the obsolete KX503R2. Both components share identical nominal resistance values and comparable B-value thermal coefficients, differing by only 2K (4140K vs. 4138K), which falls within acceptable measurement tolerances for most temperature sensing applications.

The Honeywell substitute provides an extended operating temperature range (-60°C to 150°C) compared to the KX503R2 (up to 120°C), offering greater thermal flexibility for applications requiring broader temperature coverage. Both components maintain RoHS compliance and REACH unaffected status, ensuring regulatory alignment.

The primary mechanical difference is mounting type: the KX503R2 is configured for free hanging installation, while the 192-503QET-A01 supports through-hole mounting. This distinction requires evaluation against specific circuit board assembly requirements. Both maintain identical 1.50" lead wire length, preserving spatial compatibility.

Frequently Asked Questions (FAQ)

Q: Can the 192-503QET-A01 directly replace the KX503R2 in existing designs?

A: Yes, from an electrical standpoint. Both components maintain 50kΩ resistance at 25°C with B-values within 0.05% of each other. However, the mounting type difference (free hanging vs. through-hole) requires verification against your specific PCB assembly process.

Q: What is the significance of the B-value difference (4140K vs. 4138K)?

A: The B-value defines the thermistor's temperature-resistance relationship. The 2K difference represents approximately 0.05% variance, which is negligible for most industrial temperature measurement applications operating within the 120°C range of the original KX503R2.

Q: Does the extended temperature range of the 192-503QET-A01 affect compatibility?

A: No. Extended operating range (-60°C to 150°C) provides additional capability without compromising performance within the original KX503R2's operating window (up to 120°C). This represents a superset of functionality.

Q: Are there any compliance concerns with substitution?

A: Both components maintain equivalent regulatory status. The KX503R2 is ROHS3 Compliant and REACH Unaffected, while the 192-503QET-A01 is RoHS Compliant and REACH Unaffected. Both meet current environmental standards.

Q: What inventory considerations apply?

A: The 192-503QET-A01 is currently active production with 2079 units in stock, compared to the KX503R2's obsolete status with 820 units remaining. For long-term supply chain stability, the Honeywell component is the recommended selection.