KS503R2 Equivalent & Substitute Parts

Part Overview

The KS503R2 is an NTC thermistor manufactured by Littelfuse Inc., designed as a 50kΩ bead-type temperature sensor with an epoxy package. This component is classified as obsolete, making equivalent substitutes necessary for ongoing production and maintenance applications. The part operates at a maximum temperature of 135°C with a power rating of 30 mW and features 1.50" lead wire length suitable for free-hanging mounting configurations.

Substiute Parts

KS503R2

Littelfuse Inc.In Stock: 1136KS503R2 Datasheet

Current PartRFQ

192-503QET-A01

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

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

The 192-503QET-A01 manufactured by Honeywell Sensing and Productivity Solutions qualifies as a direct substitute based on the following critical parameters:

• Identical resistance value of 50kΩ @ 25°C
• B0/50 value of 4138K, which falls within acceptable tolerance for NTC thermistor applications (2.1% B value tolerance specified)
• Matching lead wire length of 1.50" (38.00mm)
• Bead package configuration compatible with the original design
• Extended operating temperature range of -60°C to 150°C, which encompasses the original 135°C maximum
• Equivalent moisture sensitivity level (MSL 1 - Unlimited)
• Identical HTSUS and ECCN classifications

The substitute maintains functional equivalence across all specified electrical and mechanical parameters while offering active product status and improved availability.

Parameter Comparison

Engineering Selection Recommendations

The 192-503QET-A01 is the qualified substitute for the obsolete KS503R2. Selection is based on:

• Electrical equivalence: Identical 50kΩ resistance with B-value within 2.1% tolerance
• Thermal compatibility: Operating range of -60°C to 150°C exceeds the original specification
• Mechanical compatibility: Matching lead wire length and bead configuration
• Regulatory compliance: Both components maintain ROHS3/RoHS compliance and REACH unaffected status
• Supply continuity: Active product status ensures ongoing availability

The substitute is suitable for direct replacement in applications where the original KS503R2 was specified.

Frequently Asked Questions (FAQ)

Q: Can the 192-503QET-A01 be used as a direct replacement for the KS503R2?

A: Yes. Both components share identical resistance values (50kΩ), matching lead wire lengths (1.50"), and compatible bead package configurations. The B-value difference of 2K (4140K vs 4138K) represents a 0.05% variance, well within acceptable NTC thermistor tolerances.

Q: What is the difference in mounting type between these parts?

A: The KS503R2 is specified for free-hanging mounting, while the 192-503QET-A01 supports through-hole mounting. Both configurations accommodate the same 1.50" lead wire length, allowing functional equivalence in most circuit designs.

Q: Are there compliance differences between the two parts?

A: Both components are RoHS compliant and REACH unaffected. The KS503R2 carries ROHS3 certification, while the 192-503QET-A01 carries standard RoHS certification. Both maintain MSL 1 (Unlimited) moisture sensitivity ratings.

Q: Why is the KS503R2 listed as obsolete?

A: Obsolete status indicates the part is no longer manufactured by Littelfuse Inc. The 192-503QET-A01 provides functional continuity for applications requiring 50kΩ NTC thermistor sensors with equivalent electrical and mechanical specifications.

Q: What is the significance of the B-value in thermistor selection?

A: The B-value determines the temperature coefficient of resistance. The 4138K B-value of the substitute (versus 4140K for the original) results in negligible temperature response differences, maintaining thermal sensing accuracy across the operating range.