F40J250 Equivalent & Substitute Parts

Part Overview

The F40J250 is a 250 Ohms ±5% 40W wirewound chassis mount resistor manufactured by Ohmite, part of the Stackohm® 250 series. This component is designed for high-power applications requiring stable resistance performance across extended temperature ranges. The part is currently active in production with 1179 units in stock. Equivalent and substitute parts are identified when circuit design requirements, application constraints, or inventory considerations necessitate alternative component selection while maintaining functional compatibility.

Substiute Parts

F40J250

OhmiteIn Stock: 1231F40J250 Datasheet

Current PartRFQ

F30J250E

OhmiteIn Stock: 912F30J250E Datasheet

Parametric EquivalentRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the F40J250 is determined by the following critical parameters that must remain constant or compatible:

• Resistance Value: 250 Ohms (exact match required)
• Tolerance: ±5% (exact match required)
• Composition: Wirewound (exact match required)
• Temperature Coefficient: ±260ppm/°C (exact match required)
• Operating Temperature Range: -55°C to 350°C (exact match required)
• Coating/Housing Type: Vitreous Enamel Coated (exact match required)
• Mounting Feature: Flange Braces, Right Angle (exact match required)
• Lead Style: Solder Lugs (exact match required)
• Package/Case: Radial, Flat Oval (exact match required)

The F30J250E qualifies as a parametric equivalent based on matching all critical electrical and mechanical parameters. The primary difference is the power rating (30W versus 40W), which represents a derating scenario where the substitute part operates at reduced power capacity.

Parameter Comparison

Engineering Selection Recommendations

The F30J250E serves as a parametric equivalent to the F40J250 for applications where the 30W power rating is sufficient. Both components are active products from the same manufacturer and series.

The F40J250 is RoHS non-compliant, while the F30J250E is ROHS3 compliant. Applications subject to RoHS3 regulatory requirements must use the F30J250E.

The F30J250E carries a Moisture Sensitivity Level (MSL) rating of 1 (Unlimited), whereas the F40J250 lists MSL as Not Applicable. This distinction affects storage and handling protocols in moisture-sensitive environments.

Selection between these parts depends on circuit power dissipation requirements and applicable regulatory compliance mandates.

Frequently Asked Questions (FAQ)

Q: Can the F30J250E replace the F40J250 in all applications?

A: The F30J250E can replace the F40J250 only in applications where the circuit power dissipation does not exceed 30W. If the application requires the full 40W power rating, the F30J250E is not suitable.

Q: What is the primary difference between these two parts?

A: The primary difference is the power rating: F40J250 is rated for 40W, while F30J250E is rated for 30W. All other electrical and mechanical parameters are identical.

Q: Are there compliance differences between F40J250 and F30J250E?

A: Yes. The F40J250 is RoHS non-compliant, while the F30J250E is ROHS3 compliant. Applications requiring RoHS3 compliance must use the F30J250E.

Q: Do these parts have different physical dimensions?

A: The parts have different lengths. The F40J250 measures 2.000" L × 1.000" W (50.80mm × 25.40mm), while the F30J250E measures 1.250" L × 1.000" W (31.75mm × 25.40mm). Both have the same height when seated (0.563" maximum). PCB layout and mounting clearance must accommodate these dimensional differences.

Q: What is the Moisture Sensitivity Level difference?

A: The F40J250 lists MSL as Not Applicable, while the F30J250E has an MSL rating of 1 (Unlimited). This affects storage conditions and handling procedures in moisture-sensitive manufacturing environments.

Q: Are both parts from the same manufacturer?

A: Yes, both F40J250 and F30J250E are manufactured by Ohmite and belong to the Stackohm® 250 series.