PX503J2 Equivalent & Substitute Parts

Part Overview

The PX503J2 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 applications and new designs. The PX503J2 operates at a maximum temperature of 120°C with a power rating of 30 mW and features a B0/50 value of 3892K, suitable for temperature measurement and compensation applications in electronic systems.

Substiute Parts

PX503J2

Littelfuse Inc.In Stock: 921PX503J2 Datasheet

Current PartRFQ

08M5002FF

Vishay Beyschlag/Draloric/BC ComponentsIn Stock: 88508M5002FF Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the PX503J2 is determined by the following critical parameters:

• Resistance Value: 50kΩ at 25°C (primary electrical characteristic)
• Resistance Tolerance: ±1% or better (electrical accuracy requirement)
• B-Value Characteristics: Thermal response curve compatibility (B25/75 and B25/85 values within acceptable range for temperature sensing applications)
• Operating Temperature Range: Minimum 120°C upper limit to maintain functional compatibility
• Power Dissipation: Minimum 30 mW rating to support application requirements
• Package Type: Bead configuration for form factor compatibility
• RoHS Compliance: ROHS3 Compliant status for regulatory alignment

The substitute part 08M5002FF meets these criteria as an active, currently available NTC thermistor with matching 50kΩ resistance, superior operating temperature range, and higher power dissipation capability.

Parameter Comparison

Engineering Selection Recommendations

The 08M5002FF from Vishay Beyschlag/Draloric/BC Components is the qualified substitute for the obsolete PX503J2. Selection is based on the following engineering criteria:

• Electrical Equivalence: Both components maintain 50kΩ resistance at 25°C, ensuring direct functional replacement in temperature sensing circuits.
• Compliance Alignment: Both parts are ROHS3 Compliant and REACH Unaffected, meeting current regulatory requirements.
• Product Status: The 08M5002FF is active and in production, ensuring long-term availability and supply chain continuity.
• Enhanced Performance: The substitute provides superior operating temperature range (-40°C to 125°C versus 120°C maximum) and increased power dissipation (75 mW versus 30 mW), offering design margin improvements.
• Physical Compatibility: Both components use bead packaging with similar lead wire dimensions, supporting existing PCB layouts and mechanical assemblies.

Frequently Asked Questions (FAQ)

Q: Can the 08M5002FF directly replace the PX503J2 in existing designs?

A: Yes. Both components share the same 50kΩ resistance value at 25°C and bead package configuration. The substitute offers enhanced operating temperature range and power dissipation, making it functionally compatible with applications designed for the PX503J2.

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

A: The B-value defines the thermistor's thermal response curve. The 08M5002FF provides B25/75 (3925K) and B25/85 (3943K) values, which characterize its temperature sensing behavior. These values are comparable to the PX503J2's B0/50 value of 3892K, ensuring similar thermal response characteristics.

Q: Are there packaging differences between these components?

A: Both use bead-type packaging. The PX503J2 specifies "Bead, Epoxy" while the 08M5002FF specifies "Bead." Lead wire lengths differ slightly (1.50" versus 1.42"), which may require minor PCB layout adjustments but does not affect electrical performance.

Q: Does the higher power rating of the 08M5002FF affect circuit operation?

A: No. The 75 mW rating of the 08M5002FF exceeds the 30 mW requirement of the PX503J2, providing additional design margin. The actual power dissipation is determined by the application circuit, not the component rating.

Q: Are both components RoHS compliant?

A: Yes. Both the PX503J2 and 08M5002FF are ROHS3 Compliant and REACH Unaffected, meeting current environmental and regulatory standards.