SD940-T Equivalent & Substitute Parts

Part Overview

The SD940-T is a Schottky rectifier diode manufactured by Diodes Incorporated, rated for 40 V DC reverse voltage and 9 A average rectified current in a through-hole DO-201AD axial package. This component is classified as obsolete, necessitating identification of equivalent and substitute parts for ongoing design support and procurement.

Schottky diodes in this voltage and current class are used in power supply circuits, rectification applications, and reverse polarity protection where fast recovery and low forward voltage drop are required. The obsolete status of the SD940-T requires engineers to select from active alternative components that maintain electrical and mechanical compatibility.

Key Parameters

Parameter	SD940-T Value	Unit
Voltage - DC Reverse (Vr) (Max)	40	V
Current - Average Rectified (Io)	9	A
Voltage - Forward (Vf) (Max) @ If	480 mV @ 9 A	mV
Speed	Fast Recovery ≤ 500ns, > 200mA (Io)	ns
Current - Reverse Leakage @ Vr	800 µA @ 40 V	µA
Capacitance @ Vr, F	900pF @ 4V, 1MHz	pF
Mounting Type	Through Hole	—
Package / Case	DO-201AD, Axial	—
Operating Temperature - Junction	-65°C ~ 150°C	°C
Technology	Schottky	—

Substitute Part Grouping Explanation

Substitution of the SD940-T is determined by the following critical parameters:

Voltage Rating: The reverse voltage rating must equal or exceed 40 V to maintain circuit protection and reliability margins.

Current Rating: The average rectified current must equal or exceed 9 A to handle the design load without thermal stress or component failure.

Mounting Type and Package: Through-hole DO-201AD axial packages are required for direct mechanical and electrical compatibility with existing PCB layouts and assembly processes.

Technology: Schottky diode technology is specified for fast recovery characteristics and low forward voltage drop performance.

Speed Characteristics: Fast recovery with switching time ≤ 500ns at currents > 200mA is required for proper circuit operation.

Operating Temperature Range: The junction temperature range must support the application's thermal environment, with -65°C to 150°C being the baseline requirement.

Substitute parts are grouped into two categories:

Category 1 - Direct Electrical Equivalents (Through-Hole, 40V, ≥9A): Parts that maintain the same voltage rating, equal or higher current rating, through-hole mounting, and DO-201AD package format.

Category 2 - Functional Equivalents (Through-Hole, 40V, Lower Current Rating): Parts that meet voltage and package requirements but with reduced current ratings (3A to 8A), suitable for applications where the full 9A capacity is not required or where design margins permit lower-rated components.

Parameter Comparison

Part Number	Manufacturer	Vr (Max) [V]	Io [A]	Vf (Max) @ If [mV]	Package	Mounting Type	Product Status	RoHS Status
SD940-T	Diodes Incorporated	40	9	480 @ 9A	DO-201AD, Axial	Through Hole	Obsolete	ROHS3 Compliant
SBR10U45SP5-13	Diodes Incorporated	45	10	470 @ 10A	PowerDI™ 5	Surface Mount	Active	ROHS3 Compliant
1N5822	Microchip Technology	40	3	500 @ 3A	B, Axial	Through Hole	Active	RoHS non-compliant
1N5822-AP	Micro Commercial Co	40	3	525 @ 3A	DO-201AD, Axial	Through Hole	Active	Not specified
1N5822-TP	Micro Commercial Co	40	3	525 @ 3A	DO-201AD, Axial	Through Hole	Active	ROHS3 Compliant
1N5822RL	STMicroelectronics	40	3	525 @ 3A	DO-201AD, Axial	Through Hole	Active	ROHS3 Compliant
1N5822RLG	onsemi	40	3	525 @ 3A	DO-201AA, DO-27, Axial	Through Hole	Active	ROHS3 Compliant
SR304-BP	Micro Commercial Co	40	3	500 @ 3A	DO-201AD, Axial	Through Hole	Active	Not specified
SR304-TP	Micro Commercial Co	40	3	500 @ 3A	DO-201AD, Axial	Through Hole	Active	Not specified
SR804-AP	Micro Commercial Co	40	8	650 @ 8A	DO-201AD, Axial	Through Hole	Active	Not specified

Engineering Selection Recommendations

For Direct Replacement (Full 9A Capability):

The SR804-AP from Micro Commercial Co provides the closest electrical match to the SD940-T. It maintains 40 V reverse voltage rating, delivers 8 A average rectified current in the same DO-201AD through-hole axial package, and is in active product status. While the current rating is 8 A versus the original 9 A, this represents a 1 A reduction and may be acceptable depending on circuit design margins. The forward voltage at rated current is 650 mV versus 480 mV for the original part, representing a 170 mV increase that should be evaluated for thermal impact in the application.

For Reduced Current Applications (≤3A):

Multiple active alternatives exist for applications where the full 9 A capacity is not required:

1N5822-TP (Micro Commercial Co) offers ROHS3 compliance, active status, and DO-201AD package compatibility. This part is available in cut tape packaging with 10,223 units in stock.

1N5822RL (STMicroelectronics) provides ROHS3 compliance and active status with DO-201AD package compatibility. This part is available in cut tape packaging with 2,000 units in stock.

1N5822RLG (onsemi) offers ROHS3 compliance, active status, and axial package compatibility. This part is available in cut tape packaging with 1,781 units in stock.

SR304-TP (Micro Commercial Co) provides active status and DO-201AD package compatibility with 976 units in stock.

For Surface Mount Applications:

The SBR10U45SP5-13 from Diodes Incorporated is an active alternative for designs transitioning to surface mount technology. It provides 45 V reverse voltage rating, 10 A current capacity, and superior forward voltage characteristics (470 mV @ 10A). However, this part uses PowerDI™ 5 surface mount packaging and is not a direct mechanical replacement for through-hole applications.

Compliance Considerations:

ROHS3 compliance is achieved by 1N5822-TP, 1N5822RL, 1N5822RLG, and SBR10U45SP5-13. Applications requiring ROHS3 certification should prioritize these options. The original SD940-T is ROHS3 compliant, establishing this as a baseline requirement for equivalent parts.

All recommended substitutes maintain EAR99 ECCN classification and HTSUS code 8541.10.0080 consistency with the original part.

Frequently Asked Questions (FAQ)

Q: Can the 1N5822-TP directly replace the SD940-T in all applications?

A: The 1N5822-TP is electrically compatible for voltage rating (40 V) and package format (DO-201AD through-hole axial), but the current rating is reduced from 9 A to 3 A. Direct replacement is only suitable for applications where the circuit load does not exceed 3 A average rectified current. For circuits requiring the full 9 A capacity, the SR804-AP is the appropriate selection.

Q: What is the difference between 1N5822-AP and 1N5822-TP?

A: Both parts are manufactured by Micro Commercial Co with identical electrical specifications (40 V, 3 A, DO-201AD package). The primary difference is packaging format: 1N5822-AP is supplied in bulk packaging, while 1N5822-TP is supplied in cut tape (CT) format. Selection depends on procurement and assembly process requirements.

Q: Why is the SBR10U45SP5-13 listed as a substitute if it uses surface mount packaging?

A: The SBR10U45SP5-13 is included as a functional equivalent for design teams transitioning to surface mount assembly or developing new products. It provides superior electrical performance (45 V rating, 10 A capacity, 470 mV forward voltage) and active product status. However, it requires PCB redesign and is not a direct mechanical replacement for through-hole applications.

Q: What is the impact of forward voltage differences between substitute parts?

A: Forward voltage variations affect power dissipation and thermal performance. The SD940-T specifies 480 mV @ 9A, while most 3A alternatives specify 525 mV @ 3A. At equivalent current levels, higher forward voltage results in increased power loss (P = Vf × I). For the SR804-AP at 8A, the 650 mV forward voltage should be evaluated against thermal design limits. Thermal analysis is required when forward voltage increases exceed 50 mV.

Q: Are all substitute parts ROHS3 compliant?

A: No. The 1N5822 from Microchip Technology is RoHS non-compliant. The 1N5822-AP from Micro Commercial Co does not specify RoHS status. For applications requiring ROHS3 certification, select from: 1N5822-TP, 1N5822RL, 1N5822RLG, or SBR10U45SP5-13.

Q: What is the difference between DO-201AD and DO-201AA packages?

A: Both are through-hole axial diode packages with similar mechanical dimensions. The 1N5822RLG is available in DO-201AA, DO-27, and axial formats. For direct mechanical compatibility with existing PCB layouts designed for DO-201AD, confirm package dimensions with the component datasheet before substitution.

Q: Can I use a lower current rated part if my circuit only draws 5 A?

A: No. The SR804-AP (8A rating) is the minimum current-rated part suitable for 5 A applications, as it provides adequate design margin. Using a 3A-rated part (1N5822-TP, 1N5822RL, etc.) for a 5A circuit exceeds the component's rated capacity and creates reliability risk. Current ratings must equal or exceed the maximum circuit load with appropriate safety margin.

Q: What is the operating temperature range impact when selecting substitutes?

A: The SD940-T supports -65°C to 150°C junction temperature. Most 3A alternatives support -55°C to 125°C or -50°C to 125°C, representing reduced low-temperature and high-temperature capability. For applications requiring the full -65°C to 150°C range, verify substitute part datasheets. The 1N5822RLG supports -65°C to 125°C, providing improved low-temperature performance.

Q: How do I determine if reverse leakage current differences matter?

A: The SD940-T specifies 800 µA @ 40V reverse leakage. Substitute parts range from 100 µA to 2 mA. Higher reverse leakage increases standby power consumption and heat generation. For battery-powered or low-power applications, lower leakage is preferred. For standard power supply applications, leakage differences are typically negligible.

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