GS503J1K Equivalent & Substitute Parts

Part Overview

The GS503J1K is an NTC thermistor manufactured by Littelfuse Inc., featuring a 50kΩ resistance at 25°C in a glass bead package with through-hole mounting. This component is classified as obsolete, making identification of suitable substitute parts essential for ongoing design support and production continuity. The part operates at temperatures up to 300°C and is suitable for temperature sensing applications requiring high-temperature stability.

Substiute Parts

GS503J1K

Littelfuse Inc.In Stock: 1194GS503J1K Datasheet

Current PartRFQ

B57540G1503H005

EPCOS - TDK ElectronicsIn Stock: 772B57540G1503H005 Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for NTC thermistors is determined by the following critical parameters:

• Resistance Value @ 25°C: Must match the primary part (50kΩ)
• B Value (B25/85): Must be within acceptable tolerance to maintain thermal response characteristics
• Operating Temperature Range: Must support the maximum operating temperature of 300°C
• Package and Mounting: Must be identical (Bead, Glass; Through Hole)
• Resistance Tolerance: Tighter tolerance in substitutes is acceptable

The B57540G1503H005 from EPCOS - TDK Electronics meets all substitution criteria with matching 50kΩ resistance, comparable B25/85 value (3973K vs. 3977K), and identical package configuration. The substitute offers improved specifications including tighter resistance tolerance (±3% vs. ±10%) and active product status.

Parameter Comparison

Engineering Selection Recommendations

The B57540G1503H005 is a direct functional substitute for the GS503J1K. Both parts share identical resistance values, comparable B-value characteristics, and matching package configurations. The substitute offers the advantage of active product status, ensuring long-term availability and supply chain stability. The B57540G1503H005 provides ROHS3 compliance and tighter resistance tolerance, making it suitable for applications requiring improved component consistency. The extended lead wire length (2.56" vs. 1.00") must be evaluated for mechanical fit within the application assembly.

Frequently Asked Questions (FAQ)

Q: Can the B57540G1503H005 be used as a direct replacement for the GS503J1K?

A: Yes. Both thermistors have identical 50kΩ resistance at 25°C, comparable B-values (3973K vs. 3977K), and identical glass bead packages with through-hole mounting. The substitute is functionally equivalent for temperature sensing applications.

Q: What is the significance of the B-value difference (3973K vs. 3977K)?

A: The B-value determines the thermistor's thermal response curve. The difference of 4K between parts is negligible for most applications and falls within normal manufacturing variation for NTC thermistors of this class.

Q: Does the longer lead wire length affect compatibility?

A: Lead wire length is a mechanical consideration. The B57540G1503H005 has a 2.56" lead length compared to 1.00" for the GS503J1K. Verify that the longer leads fit within your circuit board layout and assembly constraints before implementation.

Q: Why is the GS503J1K obsolete?

A: The GS503J1K is classified as obsolete by the manufacturer. The B57540G1503H005 is an active product from a major thermistor manufacturer, providing assured long-term availability and supply continuity.

Q: Are there compliance differences between the two parts?

A: The B57540G1503H005 carries ROHS3 compliance certification, while the GS503J1K does not specify RoHS status. Both parts are REACH Unaffected and carry EAR99 ECCN classification.