SD940-B Equivalent & Substitute Parts

Part Overview

The SD940-B is a Schottky rectifier diode manufactured by Diodes Incorporated, rated for 40 V DC reverse voltage and 9 A average rectified current in a DO-201AD axial through-hole package. This part 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 through-hole DO-201AD package format.

Substiute Parts

SD940-B

Diodes IncorporatedIn Stock: 837SD940-B Datasheet

Current PartRFQ

SB340EA-G

Comchip TechnologyIn Stock: 744SB340EA-G Datasheet

MFR RecommendedRFQ

SB540B-G

Comchip TechnologyIn Stock: 879SB540B-G Datasheet

MFR RecommendedRFQ

SR1204

Taiwan Semiconductor CorporationIn Stock: 2130SR1204 Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the SD940-B are selected based on strict electrical and mechanical compatibility criteria. All candidates must satisfy the following requirements:

Mandatory Compatibility Parameters:

• Voltage - DC Reverse (Vr) (Max): 40 V minimum
• Package / Case: DO-201AD, Axial (through-hole)
• Technology: Schottky
• Speed: Fast Recovery ≤ 500ns, > 200mA (Io)
• RoHS Status: ROHS3 Compliant
• Mounting Type: Through Hole

Current Rating Consideration: The SD940-B is rated for 9 A average rectified current. Substitute parts are grouped by current capacity relative to this specification. Parts rated at or above 9 A provide direct replacement capability. Parts rated below 9 A are listed as substitutes only where circuit design permits reduced current handling.

Three active substitute parts meet the mandatory electrical and mechanical criteria:

1. SR1204 (Taiwan Semiconductor Corporation) – 12 A rating, exceeds SD940-B current specification
2. SB540B-G (Comchip Technology) – 5 A rating, below SD940-B current specification
3. SB340EA-G (Comchip Technology) – 3 A rating, below SD940-B current specification

Parameter Comparison

Engineering Selection Recommendations

SR1204 (Taiwan Semiconductor Corporation)

The SR1204 is the primary substitute for the SD940-B. It is an active product with a 12 A current rating that exceeds the SD940-B specification, providing direct electrical replacement with enhanced current capacity. The SR1204 maintains 40 V reverse voltage rating, fast recovery switching speed, and ROHS3 compliance. Operating temperature range is -50°C to 150°C, which covers the SD940-B lower temperature limit of -65°C with upper temperature equivalence. Reverse leakage current is reduced to 500 µA, improving performance characteristics. The SR1204 is available in Cut Tape packaging with 2076 pieces in stock.

SB540B-G (Comchip Technology)

The SB540B-G is an active substitute suitable for applications where the 9 A current requirement can be reduced to 5 A. It maintains 40 V reverse voltage, fast recovery speed, and ROHS3 compliance. Forward voltage is 550 mV at 5 A, and reverse leakage is 500 µA. Operating temperature range is -65°C to 125°C. This part is available in Bulk packaging with 842 pieces in stock. Selection of this part requires circuit analysis to confirm that 5 A current capacity is sufficient for the application.

SB340EA-G (Comchip Technology)

The SB340EA-G is an active substitute for applications requiring only 3 A current capacity. It maintains 40 V reverse voltage, fast recovery speed, and ROHS3 compliance. Forward voltage is 500 mV at 3 A, and reverse leakage is 500 µA. Operating temperature range is -65°C to 125°C. This part is available in Tape & Box packaging with 725 pieces in stock. Selection of this part requires circuit analysis to confirm that 3 A current capacity is sufficient for the application.

Frequently Asked Questions (FAQ)

Q: Can SR1204 directly replace SD940-B without circuit modification?

A: Yes. The SR1204 maintains the same 40 V reverse voltage rating, DO-201AD package, and fast recovery switching characteristics. The 12 A current rating exceeds the 9 A requirement, providing direct electrical compatibility. No circuit modification is required.

Q: Why are SB540B-G and SB340EA-G listed as substitutes if their current ratings are lower than SD940-B?

A: These parts are listed as substitutes because they satisfy all mandatory electrical and mechanical compatibility criteria: 40 V reverse voltage, DO-201AD package, Schottky technology, fast recovery speed, and ROHS3 compliance. However, their reduced current ratings (5 A and 3 A respectively) require circuit analysis to confirm applicability. They are suitable only for applications where the actual circuit current demand is at or below their rated capacity.

Q: What is the difference between the packaging options for these substitutes?

A: SR1204 is supplied in Cut Tape (CT) format, suitable for automated assembly. SB540B-G is supplied in Bulk format, suitable for manual assembly or high-volume reel applications. SB340EA-G is supplied in Tape & Box (TB) format, providing organized packaging for component management. All three parts are functionally equivalent in the DO-201AD through-hole package.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. The SD940-B and all three substitute parts (SR1204, SB540B-G, SB340EA-G) are ROHS3 compliant, meeting environmental and regulatory requirements for new designs and production.

Q: What is the temperature operating range difference between SD940-B and the substitutes?

A: The SD940-B operates from -65°C to 150°C. SR1204 operates from -50°C to 150°C, providing equivalent upper temperature performance but with a 15°C higher lower temperature limit. SB540B-G and SB340EA-G both operate from -65°C to 125°C, matching the lower temperature limit but with a 25°C lower upper temperature limit. Temperature range selection depends on circuit requirements.

Q: How do reverse leakage currents compare between these parts?

A: The SD940-B has a reverse leakage current of 800 µA at 40 V. All three substitute parts (SR1204, SB540B-G, SB340EA-G) have reduced reverse leakage of 500 µA at 40 V, representing improved performance characteristics that reduce standby power consumption and heat generation.