SS24 Schottky Diode 40V 2A Equivalent & Substitute Parts

Part Overview

The onsemi SS24 is a Schottky rectifier diode rated for 40V reverse voltage and 2A average rectified current in a DO-214AA (SMB) surface mount package. This part is classified as obsolete, necessitating identification of active equivalent and substitute components for new designs and production applications. Equivalent parts maintain identical electrical and mechanical specifications, while substitute parts offer functional compatibility within defined parameter tolerances for 40V/2A Schottky diode applications.

Key Parameters

Parameter	Value	Unit
Voltage - DC Reverse (Vr) Maximum	40	V
Current - Average Rectified (Io)	2	A
Voltage - Forward (Vf) Maximum @ If	500	mV @ 2A
Speed - Fast Recovery	≤ 500	ns, > 200mA (Io)
Current - Reverse Leakage @ Vr	400	µA @ 40V
Technology	Schottky	—
Mounting Type	Surface Mount	—
Package / Case	DO-214AA, SMB	—
Operating Temperature - Junction	-65 to 125	°C
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitution of the SS24 Schottky diode is determined by the following critical parameters:

Mandatory Matching Criteria:

Voltage - DC Reverse (Vr) Maximum: 40V
Current - Average Rectified (Io): 2A
Technology: Schottky
Mounting Type: Surface Mount
Package / Case: DO-214AA or DO-214AC (SMB or SMA variants)
Speed: Fast Recovery ≤ 500ns, > 200mA (Io)

Allowable Variation Ranges:

Voltage - Forward (Vf) @ 2A: 430–550 mV (within design margin)
Current - Reverse Leakage @ 40V: 200 nA to 500 µA (acceptable for most applications)
Operating Temperature - Junction: -55°C to 150°C (extended range acceptable)

Parts are grouped as Direct Equivalents when all electrical parameters match within specification, and as Functional Substitutes when voltage and current ratings are identical but forward voltage or leakage characteristics differ within acceptable ranges.

Parameter Comparison

Part Number	Manufacturer	Vr (Max) [V]	Io [A]	Vf (Max) @ 2A [mV]	Ir @ 40V [µA]	Package	Temp Range [°C]	Product Status	RoHS
SS24	onsemi	40	2	500	400	DO-214AA (SMB)	-65 to 125	Obsolete	ROHS3
SS24T3G	onsemi	40	2	500	400	DO-214AA (SMB)	-55 to 150	Active	ROHS3
MBRS240LT3G	onsemi	40	2	430	2000	DO-214AA (SMB)	-55 to 150	Active	ROHS3
B240A-13-F	Diodes Incorporated	40	2	500	500	DO-214AC (SMA)	-65 to 150	Active	ROHS3
SK24	Good-Ark Semiconductor	40	2	550	0.2	DO-214AA (SMB)	-55 to 150	Active	ROHS3
SS24/1	Vishay General Semiconductor	40	2	500	400	DO-214AA (SMB)	-65 to 125	Active	Non-compliant
STPS2L40U	STMicroelectronics	40	2	430	220	DO-214AA (SMB)	-55 to 150	Active	ROHS3
B240-13-F	Diodes Incorporated	40	2	500	500	DO-214AA (SMB)	-65 to 150	Active	ROHS3

Engineering Selection Recommendations

Primary Recommendation: SS24T3G (onsemi)

SS24T3G is the direct active equivalent of the obsolete SS24. It maintains identical electrical specifications (40V, 2A, 500 mV forward voltage, 400 µA reverse leakage) and package format (DO-214AA SMB). The part is ROHS3 compliant and carries active product status. Operating temperature range extends to 150°C maximum, providing improved thermal margin over the original SS24 specification of 125°C.

Secondary Recommendations:

STPS2L40U (STMicroelectronics) and MBRS240LT3G (onsemi) are functional substitutes with identical 40V/2A ratings. Both feature reduced forward voltage (430 mV @ 2A) compared to the SS24 specification, resulting in lower power dissipation. STPS2L40U exhibits 220 µA reverse leakage, while MBRS240LT3G exhibits 2 mA reverse leakage. Both are ROHS3 compliant with active product status and extended temperature range to 150°C.

B240-13-F (Diodes Incorporated) is a functional substitute in DO-214AA SMB package with matching 40V/2A/500 mV specifications. It provides extended temperature range to 150°C and ROHS3 compliance. This part is suitable for applications requiring identical electrical performance with alternative manufacturer sourcing.

B240A-13-F (Diodes Incorporated) is a functional substitute in DO-214AC SMA package (smaller footprint than SMB). Electrical specifications match the SS24 (40V, 2A, 500 mV). Package change from SMB to SMA requires PCB layout modification and is suitable only for new designs with space constraints.

SK24 (Good-Ark Semiconductor) is a functional substitute with slightly elevated forward voltage (550 mV @ 2A) and exceptionally low reverse leakage (0.2 µA @ 40V). This part is suitable for applications prioritizing leakage minimization. DO-214AA SMB package maintains mechanical compatibility.

SS24/1 (Vishay General Semiconductor) maintains identical electrical specifications to the original SS24 but carries RoHS non-compliant status. This part is not recommended for new designs or applications requiring RoHS3 compliance.

Not Recommended for Direct Substitution:

B140B-13-F, B140BQ-13-F, and B140HB-13-F are 1A-rated Schottky diodes. These parts do not meet the 2A current requirement and are unsuitable for SS24 replacement.

Frequently Asked Questions (FAQ)

Q: Can SS24T3G directly replace the obsolete SS24 without design changes?

A: Yes. SS24T3G is the direct active equivalent with identical electrical specifications (40V, 2A, 500 mV forward voltage, 400 µA reverse leakage) and DO-214AA SMB package. No circuit or PCB modifications are required. The extended operating temperature range (150°C maximum) provides additional thermal margin.

Q: What is the difference between SMB and SMA packages?

A: SMB (DO-214AA) and SMA (DO-214AC) are both surface mount packages for Schottky diodes but differ in physical dimensions. SMA is smaller. B240A-13-F uses SMA packaging and requires PCB layout modification. SMB-packaged alternatives (SS24T3G, STPS2L40U, B240-13-F, SK24) maintain mechanical compatibility with the original SS24 footprint.

Q: Why do some substitutes have lower forward voltage (430 mV vs. 500 mV)?

A: Forward voltage variation is a normal characteristic of Schottky diode manufacturing. MBRS240LT3G and STPS2L40U exhibit 430 mV forward voltage at 2A, which is within acceptable design margins and results in lower power dissipation. This is acceptable for most applications unless the circuit design specifically requires the higher 500 mV specification.

Q: Are all recommended substitutes RoHS3 compliant?

A: All primary and secondary recommendations (SS24T3G, STPS2L40U, MBRS240LT3G, B240-13-F, B240A-13-F, SK24) are ROHS3 compliant. SS24/1 is RoHS non-compliant and is not recommended for new designs.

Q: What is the significance of reverse leakage current variation?

A: Reverse leakage current ranges from 0.2 µA (SK24) to 2 mA (MBRS240LT3G) across the substitute options. The original SS24 specifies 400 µA. Higher leakage increases standby power consumption; lower leakage reduces it. Selection depends on application requirements. For most rectification applications, leakage variation within this range is acceptable.

Q: Can B140-series 1A diodes be used as substitutes?

A: No. B140B-13-F, B140BQ-13-F, and B140HB-13-F are rated for 1A maximum current, not 2A. These parts do not meet the SS24 current requirement and will experience thermal stress or failure in 2A applications. These parts are not suitable substitutes.

Q: What is the operating temperature range consideration?

A: The original SS24 operates from -65°C to 125°C. Most active substitutes extend the maximum temperature to 150°C, providing improved thermal margin. SS24T3G maintains the -65°C minimum but extends maximum to 150°C. For applications operating near 125°C, the extended range of active substitutes provides design safety margin.

Q: Is package compatibility critical for PCB assembly?

A: Yes. The original SS24 uses DO-214AA (SMB) package. Direct replacements (SS24T3G, STPS2L40U, B240-13-F, SK24, SS24/1) maintain this package and require no PCB modification. B240A-13-F uses DO-214AC (SMA) package and requires PCB layout redesign. Package selection must match the existing PCB footprint unless redesign is planned.

Request Quote (Ships tomorrow)

Part Number

Quantity

Company

Contact Name

E-mail

Message