1A4 Equivalent & Substitute Parts

Part Overview

The 1A4 is a general-purpose rectifier diode manufactured by SMC Diode Solutions, rated for 400 V DC reverse voltage and 1 A average rectified current in an R-1 axial through-hole package. This component is classified as obsolete, indicating that direct procurement from the original manufacturer is no longer available. Identifying equivalent substitute parts is necessary to maintain design continuity and ensure uninterrupted supply for applications requiring this diode specification.

Substiute Parts

1A4

SMC Diode SolutionsIn Stock: 12701A4 Datasheet

Current PartRFQ

1N4004G

Rectron USAIn Stock: 103101N4004G Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the 1A4 are identified based on electrical and mechanical compatibility within the rectifier diode category. The substitution criteria are strictly limited to the following parameters:

• Voltage Rating: DC reverse voltage must equal or exceed 400 V
• Current Rating: Average rectified current must equal or exceed 1 A
• Forward Voltage: Maximum forward voltage at rated current must not exceed 1 V @ 1 A
• Recovery Speed: Standard recovery characteristics >500ns, > 200mA (Io)
• Reverse Leakage: Current leakage at rated voltage must be within acceptable limits for the application
• Capacitance: Junction capacitance at specified conditions must match or be compatible
• Mounting Type: Through-hole configuration required for mechanical compatibility
• Operating Temperature Range: Must support the -65°C to 125°C minimum junction temperature range
• Package Compatibility: Physical dimensions and lead configuration must permit direct substitution or adapter use

The 1N4004G meets all specified electrical parameters and operates within the required temperature range, making it a valid substitute for the obsolete 1A4.

Parameter Comparison

Engineering Selection Recommendations

The 1N4004G manufactured by Rectron USA is a direct electrical equivalent to the obsolete 1A4. Both components share identical voltage, current, and forward voltage specifications, ensuring functional compatibility in existing circuit designs.

The 1N4004G offers the following advantages:

• Active Product Status: Currently in production and widely available (10,300 pcs in stock), eliminating supply chain risk associated with the obsolete 1A4
• Extended Operating Temperature Range: Rated to -65°C ~ 175°C versus the 1A4's -65°C ~ 125°C, providing additional thermal margin in high-temperature applications
• Improved Reverse Leakage Characteristics: 200 nA @ 400 V compared to 5 µA @ 400 V, resulting in lower power dissipation and improved circuit efficiency
• Automotive Qualification: AEC-Q101 certified and automotive-grade, indicating compliance with automotive reliability standards
• RoHS3 Compliance: Meets current environmental and hazardous substance restrictions

The primary consideration for substitution is package compatibility. The 1A4 uses an R-1 axial package, while the 1N4004G uses a DO-41 (DO-204AL) axial package. Both are through-hole axial configurations with similar physical dimensions, permitting direct board-level substitution without circuit modification.

Frequently Asked Questions (FAQ)

Q: Can the 1N4004G directly replace the 1A4 without circuit modification?

A: Yes. Both components are through-hole axial diodes with equivalent electrical specifications (400 V, 1 A, 1 V forward voltage). The R-1 and DO-41 packages are mechanically compatible for through-hole mounting. No circuit changes are required.

Q: What is the difference between the R-1 and DO-41 packages?

A: Both are axial through-hole packages with two leads. The R-1 and DO-41 (DO-204AL) designations refer to different standardized package outlines, but both accommodate standard 0.040-inch lead diameter and are compatible with conventional PCB through-hole spacing. Physical dimensions are similar, permitting direct substitution.

Q: Why is the 1N4004G's reverse leakage current lower than the 1A4?

A: The 1N4004G exhibits 200 nA reverse leakage compared to the 1A4's 5 µA at 400 V. This difference reflects manufacturing process improvements and tighter quality control in the active 1N4004G product line. Lower leakage reduces power dissipation and improves circuit efficiency, particularly in high-impedance applications.

Q: Is the extended temperature range of the 1N4004G (-65°C ~ 175°C) a concern for compatibility?

A: No. The extended range is a superset of the 1A4's -65°C ~ 125°C specification. The 1N4004G operates safely within the original design temperature envelope and provides additional margin for applications requiring higher thermal performance.

Q: Does the 1N4004G's automotive qualification affect its use in non-automotive applications?

A: No. Automotive qualification (AEC-Q101) indicates enhanced reliability testing and quality assurance. These characteristics are beneficial in all applications and do not restrict use to automotive circuits.

Q: What is the significance of RoHS3 compliance on the 1N4004G?

A: RoHS3 compliance confirms that the 1N4004G meets current European Union restrictions on hazardous substances. This certification is relevant for products destined for EU markets and reflects adherence to modern environmental standards. It does not affect electrical performance or compatibility.

Q: Are there any package-related considerations when substituting the 1N4004G for the 1A4?

A: Both components use axial through-hole packages with standard lead spacing. Verify that PCB footprints accommodate the specific package dimensions of the 1N4004G (DO-41). In most applications with standard through-hole spacing, direct substitution is possible without PCB modification.

Q: What inventory status should be considered when selecting between the 1A4 and 1N4004G?

A: The 1A4 is obsolete with limited remaining stock (1,172 pcs). The 1N4004G is an active product with substantial availability (10,300 pcs). For new designs or long-term production, the 1N4004G is the recommended choice to ensure supply continuity.