IRD3903 Equivalent & Substitute Parts

Part Overview

The IRD3903 is a general-purpose 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, necessitating identification of active equivalent alternatives for new designs and ongoing production requirements. Substitute parts must maintain electrical compatibility across voltage, current, and thermal specifications while accommodating the stud mount mechanical interface.

Key Parameters

Parameter	IRD3903 Value
Voltage - DC Reverse (Vr) (Max)	400 V
Current - Average Rectified (Io)	20 A
Voltage - Forward (Vf) (Max)	1.65 V @ 62.8 A
Reverse Recovery Time (trr)	350 ns
Current - Reverse Leakage @ Vr	50 µA @ 400 V
Speed Classification	Fast Recovery ≤ 500ns, > 200mA (Io)
Mounting Type	Chassis, Stud Mount
Package / Case	DO-203AB, DO-5, Stud
Operating Temperature - Junction	-40°C ~ 125°C
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitution eligibility for the IRD3903 is determined by the following critical parameters:

Mandatory Compatibility Criteria:

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

Current Rating Consideration: The IRD3903 specifies 20 A average rectified current. Substitute parts with equal or higher current ratings (20 A or greater) are electrically compatible, as they can safely conduct the required current without exceeding thermal or electrical stress limits.

Reverse Recovery Time: The IRD3903 exhibits a reverse recovery time of 350 ns. Substitute parts with equal or faster recovery times (≤ 350 ns) maintain or improve switching performance characteristics.

Reverse Leakage Current: The IRD3903 specifies 50 µA reverse leakage at 400 V. Substitute parts with equal or lower leakage current values maintain or improve reverse bias performance.

Parameter Comparison

Parameter	IRD3903	1N3903	1N3913	1N3913A
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
Reverse Recovery Time (trr)	350 ns	200 ns	200 ns	150 ns
Current - Reverse Leakage @ Vr	50 µA @ 400 V	50 µA @ 400 V	15 µA @ 400 V	15 µA @ 400 V
Speed Classification	Fast Recovery ≤ 500ns, > 200mA	Fast Recovery ≤ 500ns, > 200mA	Fast Recovery ≤ 500ns, > 200mA	Fast Recovery ≤ 500ns, > 200mA
Mounting Type	Chassis, Stud Mount	Stud Mount	Stud Mount	Stud Mount
Package / Case	DO-203AB, DO-5, Stud	DO-203AB, DO-5, Stud	DO-203AB, DO-5, Stud	DO-203AB, DO-5, Stud
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

1N3903 (Microchip Technology)

The 1N3903 is an active equivalent providing identical voltage and current ratings to the IRD3903. This part maintains the 400 V reverse voltage specification and 20 A average rectified current. The 1N3903 exhibits improved reverse recovery time (200 ns versus 350 ns) and expanded operating temperature range (-65°C to 150°C versus -40°C to 125°C). However, the 1N3903 is RoHS non-compliant, which may impact suitability for applications requiring RoHS3 compliance. This part is suitable for direct replacement in applications where RoHS compliance is not mandated.

1N3913 (Microchip Technology)

The 1N3913 provides 400 V reverse voltage compatibility with an elevated current rating of 50 A, exceeding the IRD3903 requirement of 20 A. This higher current capacity allows operation with additional design margin. The 1N3913 delivers improved reverse recovery time (200 ns) and significantly reduced reverse leakage current (15 µA versus 50 µA). The expanded operating temperature range (-65°C to 150°C) accommodates broader thermal environments. The 1N3913 is RoHS non-compliant. This part is suitable for applications requiring enhanced current handling capacity and improved switching performance.

1N3913A (Microchip Technology)

The 1N3913A provides identical voltage and current specifications to the 1N3913 with further optimized reverse recovery time (150 ns). This represents the fastest switching performance among available substitutes. The 1N3913A maintains the 50 A current rating and 15 µA reverse leakage current. The expanded operating temperature range (-65°C to 150°C) provides thermal flexibility. The 1N3913A is RoHS non-compliant. This part is suitable for applications prioritizing switching speed and thermal performance within non-RoHS environments.

Frequently Asked Questions (FAQ)

Q: Can the 1N3903 directly replace the IRD3903 in all applications?

A: The 1N3903 maintains identical voltage (400 V) and current (20 A) ratings with improved reverse recovery time and expanded operating temperature range. Direct mechanical and electrical substitution is valid for applications not requiring RoHS3 compliance. Verify that the application does not mandate RoHS compliance before implementation.

Q: Why do the 1N3913 and 1N3913A have higher current ratings (50 A) than the IRD3903 (20 A)?

A: Higher current ratings indicate increased thermal and electrical capacity. A 50 A rated diode can safely conduct 20 A with additional design margin. This provides operational headroom and may improve thermal performance in the application. No circuit modification is required for substitution.

Q: What is the significance of reverse recovery time differences between these parts?

A: Reverse recovery time (trr) affects switching speed and switching losses in rectifier applications. The IRD3903 specifies 350 ns, while the 1N3913 and 1N3913A specify 200 ns and 150 ns respectively. Faster recovery times reduce switching losses and improve efficiency in high-frequency applications. All parts meet the Fast Recovery classification (≤ 500ns).

Q: Are there compliance differences between the IRD3903 and substitute parts?

A: The IRD3903 is ROHS3 compliant, while the 1N3903, 1N3913, and 1N3913A are RoHS non-compliant. Applications requiring RoHS3 certification must retain the IRD3903 or identify alternative compliant sources. All parts are REACH unaffected and carry EAR99 ECCN classification.

Q: Do the substitute parts fit the same DO-203AB (DO-5) stud mount package?

A: Yes. All substitute parts (1N3903, 1N3913, 1N3913A) are specified for DO-203AB, DO-5, or Stud mount packages. Mechanical compatibility with existing stud mount hardware is maintained across all alternatives.

Q: What is the operating temperature range difference, and does it matter?

A: The IRD3903 operates from -40°C to 125°C, while all Microchip substitutes operate from -65°C to 150°C. The expanded range provides thermal flexibility for applications in extreme environments. For standard industrial applications (-40°C to 125°C), both ranges are functionally equivalent.

Q: Which substitute part should be selected for new designs?

A: Selection depends on application requirements. For direct 20 A replacement with improved performance, use the 1N3903. For applications requiring higher current capacity and improved switching characteristics, use the 1N3913 or 1N3913A. The 1N3913A offers the fastest switching performance. Verify RoHS compliance requirements before final selection.

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