IRD3903R Equivalent & Substitute Parts

Part Overview

The IRD3903R is a general-purpose fast recovery rectifier diode manufactured by Vishay General Semiconductor - Diodes Division, rated for 400 V DC reverse voltage and 20 A average rectified current in a DO-203AB (DO-5) stud mount package. This component is classified as obsolete, indicating discontinuation from the original manufacturer. Identification of equivalent and substitute parts is necessary to maintain design continuity and ensure component availability for new production runs, repairs, and system upgrades.

Key Parameters

Parameter	Value
Voltage - DC Reverse (Vr) (Max)	400 V
Current - Average Rectified (Io)	20 A
Voltage - Forward (Vf) (Max)	1.65 V @ 62.8 A
Speed Classification	Fast Recovery ≤ 500ns, > 200mA (Io)
Reverse Recovery Time (trr)	350 ns
Current - Reverse Leakage @ Vr	50 µA @ 400 V
Mounting Type	Chassis, Stud Mount
Package / Case	DO-203AB (DO-5)
Operating Temperature - Junction	-40°C ~ 125°C
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitution of the IRD3903R is determined by strict equivalence across the following critical parameters:

Primary Substitution Criteria:

Voltage - DC Reverse (Vr) (Max): 400 V
Mounting Type: Stud Mount
Package / Case: DO-203AB (DO-5)
Speed Classification: Fast Recovery ≤ 500ns, > 200mA (Io)

Current Rating Considerations: The IRD3903R operates at 20 A average rectified current. Substitute parts with equal or higher current ratings (20 A or greater) satisfy the minimum electrical requirements for direct replacement. Parts rated above 20 A provide additional design margin and are electrically compatible.

Reverse Recovery Time: The IRD3903R specifies a reverse recovery time of 350 ns. Substitute parts with equal or faster recovery times (≤ 350 ns) maintain or improve switching performance characteristics.

Temperature Range: The IRD3903R operates from -40°C to 125°C. Substitute parts with equal or extended temperature ranges are compatible with the original design envelope.

Parameter Comparison

Parameter	IRD3903R (Main)	1N3903R	1N3913AR	1N3913R
Manufacturer	Vishay General Semiconductor	Microchip Technology	Microchip Technology	Microchip Technology
Product Status	Obsolete	Active	Active	Active
Voltage - DC Reverse (Vr) (Max)	400 V	400 V	400 V	400 V
Current - Average Rectified (Io)	20 A	20 A	50 A	50 A
Voltage - Forward (Vf) (Max)	1.65 V @ 62.8 A	1.4 V @ 63 A	1.4 V @ 50 A	1.4 V @ 50 A
Speed Classification	Fast Recovery ≤ 500ns, > 200mA	Fast Recovery ≤ 500ns, > 200mA	Fast Recovery ≤ 500ns, > 200mA	Fast Recovery ≤ 500ns, > 200mA
Reverse Recovery Time (trr)	350 ns	200 ns	150 ns	200 ns
Current - Reverse Leakage @ Vr	50 µA @ 400 V	50 µA @ 400 V	15 µA @ 400 V	15 µA @ 400 V
Mounting Type	Chassis, Stud Mount	Stud Mount	Stud Mount	Stud Mount
Package / Case	DO-203AB (DO-5)	DO-203AB (DO-5)	DO-203AB (DO-5)	DO-203AB (DO-5)
Operating Temperature - Junction	-40°C ~ 125°C	-65°C ~ 150°C	-65°C ~ 150°C	-65°C ~ 150°C
RoHS Status	ROHS3 Compliant	RoHS non-compliant	RoHS non-compliant	RoHS non-compliant

Engineering Selection Recommendations

1N3903R (Microchip Technology)

The 1N3903R is a direct electrical equivalent to the IRD3903R, matching the 400 V reverse voltage rating and 20 A average rectified current specification. This part is currently in active production status, ensuring long-term availability. The 1N3903R exhibits improved performance characteristics with a forward voltage of 1.4 V (compared to 1.65 V) and a faster reverse recovery time of 200 ns (compared to 350 ns). The extended operating temperature range of -65°C to 150°C provides additional thermal margin. However, the 1N3903R carries RoHS non-compliant status, which may impact suitability for applications subject to RoHS regulations.

1N3913R and 1N3913AR (Microchip Technology)

Both the 1N3913R and 1N3913AR are rated for 50 A average rectified current, providing 2.5× the current capacity of the IRD3903R while maintaining the same 400 V reverse voltage rating and DO-203AB stud mount package. These parts are suitable for applications where the IRD3903R operates below its maximum current rating and where additional design margin is acceptable. The 1N3913R and 1N3913AR both feature improved reverse recovery times (200 ns and 150 ns respectively) and reduced reverse leakage current (15 µA compared to 50 µA). Both parts are in active production status. The 1N3913AR exhibits the fastest reverse recovery time at 150 ns. Like the 1N3903R, both 1N3913 variants are RoHS non-compliant.

Compliance Considerations

The IRD3903R is ROHS3 compliant, while all three substitute parts (1N3903R, 1N3913R, 1N3913AR) are RoHS non-compliant. Applications requiring RoHS compliance must address this discrepancy through design review or alternative component sourcing.

Frequently Asked Questions (FAQ)

Q: Can the 1N3903R directly replace the IRD3903R?

A: Yes. The 1N3903R matches the IRD3903R across all critical electrical parameters: 400 V reverse voltage, 20 A average rectified current, fast recovery speed classification, and DO-203AB stud mount package. The 1N3903R is in active production, addressing the obsolescence of the IRD3903R.

Q: What is the difference between the 1N3913R and 1N3913AR?

A: Both parts are rated for 50 A average rectified current and 400 V reverse voltage in the same DO-203AB package. The primary difference is reverse recovery time: the 1N3913AR specifies 150 ns while the 1N3913R specifies 200 ns. Both are electrically compatible with the IRD3903R for applications operating below 20 A.

Q: Can I use a 50 A rated diode (1N3913R or 1N3913AR) in place of the 20 A IRD3903R?

A: Yes. The 50 A rated parts are electrically compatible with the IRD3903R when the application current does not exceed 20 A. The higher current rating provides additional design margin and does not degrade performance in lower-current applications.

Q: Are there package compatibility concerns with these substitutes?

A: No. All substitute parts use the DO-203AB (DO-5) stud mount package, identical to the IRD3903R. Mechanical mounting and electrical connection are directly compatible.

Q: What is the impact of the faster reverse recovery time in the substitute parts?

A: The substitute parts exhibit faster reverse recovery times (150–200 ns) compared to the IRD3903R (350 ns). Faster recovery times reduce switching losses and improve high-frequency performance. This represents an improvement over the original part and does not introduce compatibility issues.

Q: Do the substitute parts have different temperature operating ranges?

A: Yes. The IRD3903R operates from -40°C to 125°C, while all substitute parts operate from -65°C to 150°C. The extended range of the substitutes provides additional thermal margin and is compatible with the original design envelope.

Q: What is the significance of the RoHS compliance difference?

A: The IRD3903R is ROHS3 compliant, while the substitute parts are RoHS non-compliant. Applications subject to RoHS regulations must address this discrepancy through design review, regulatory exemption documentation, or alternative component sourcing.

Q: How do forward voltage differences affect circuit performance?

A: The IRD3903R specifies 1.65 V forward voltage at 62.8 A, while the substitute parts specify 1.4 V at their respective test currents. The lower forward voltage in the substitutes results in reduced power dissipation and improved efficiency. This represents an improvement and does not introduce compatibility issues.

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