SK18-LTP Equivalent & Substitute Parts

Part Overview

The SK18-LTP is a Schottky rectifier diode rated for 80 V DC reverse voltage and 1 A average rectified current in a DO-214AA (SMB) surface mount package. This component is classified as "Not For New Designs," indicating it has been superseded in the manufacturer's product line. Identifying equivalent and substitute parts is necessary for ongoing production support, legacy system maintenance, and design flexibility when the primary part becomes unavailable.

Key Parameters

Parameter	Value
Voltage - DC Reverse (Vr) (Max)	80 V
Current - Average Rectified (Io)	1 A
Voltage - Forward (Vf) (Max) @ If	850 mV @ 1 A
Speed	Fast Recovery ≤ 500ns, > 200mA (Io)
Current - Reverse Leakage @ Vr	500 µA @ 80 V
Package / Case	DO-214AA, SMB
Mounting Type	Surface Mount
Operating Temperature - Junction	-55°C ~ 125°C
Technology	Schottky
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution eligibility for the SK18-LTP is determined by the following critical parameters:

Mandatory Matching Parameters:

Voltage - DC Reverse (Vr) (Max): 80 V
Package / Case: DO-214AA or SMB equivalent
Mounting Type: Surface Mount
Technology: Schottky
RoHS Status: ROHS3 Compliant

Allowable Variation Parameters:

Current - Average Rectified (Io): Equal to or greater than 1 A
Voltage - Forward (Vf) (Max) @ If: Within acceptable forward voltage range for Schottky rectifiers
Current - Reverse Leakage @ Vr: Within acceptable leakage specifications
Operating Temperature - Junction: Equal to or wider than -55°C ~ 125°C
Capacitance @ Vr, F: Variation acceptable based on application requirements

Parts are grouped as Parametric Equivalents when all mandatory parameters match exactly and current rating equals 1 A. Parts are grouped as Similar when mandatory parameters match but current rating exceeds 1 A or other secondary parameters vary within acceptable engineering tolerances.

Parameter Comparison

Manufacturer Part Number	Manufacturer	Vr (Max)	Io	Vf (Max) @ If	Package	Reverse Leakage @ Vr	Operating Temp (Junction)	Product Status	RoHS Status
SK18-LTP	Micro Commercial Co	80 V	1 A	850 mV @ 1 A	DO-214AA, SMB	500 µA @ 80 V	-55°C ~ 125°C	Not For New Designs	ROHS3 Compliant
SK18-TP (SMBSR108)	Micro Commercial Co	80 V	1 A	850 mV @ 1 A	DO-214AA, SMB	500 µA @ 80 V	-55°C ~ 125°C	Active	ROHS3 Compliant
B180B-13-F	Diodes Incorporated	80 V	1 A	790 mV @ 1 A	DO-214AA, SMB	500 µA @ 80 V	-65°C ~ 150°C	Active	ROHS3 Compliant
B280-13-F	Diodes Incorporated	80 V	2 A	790 mV @ 2 A	DO-214AA, SMB	7 mA @ 80 V	-65°C ~ 150°C	Active	ROHS3 Compliant
SK38B/TR13	Microsemi Corporation	80 V	3 A	850 mV @ 3 A	DO-214AA, SMB	500 µA @ 80 V	-55°C ~ 125°C	Active	RoHS non-compliant
SS28	onsemi	80 V	2 A	850 mV @ 2 A	DO-214AA, SMB	400 µA @ 80 V	-65°C ~ 125°C	Not For New Designs	ROHS3 Compliant
SK18	Diotec Semiconductor	80 V	1 A	850 mV @ 1 A	DO-214AC, SMA	200 µA @ 80 V	-50°C ~ 150°C	Active	ROHS3 Compliant

Engineering Selection Recommendations

Primary Substitute (Parametric Equivalent):

SK18-TP (SMBSR108) from Micro Commercial Co is the direct parametric equivalent to SK18-LTP. This part maintains identical electrical specifications (80 V, 1 A, 850 mV forward voltage) and package configuration (DO-214AA, SMB). The critical distinction is product status: SK18-TP is Active, whereas SK18-LTP is Not For New Designs. For new designs and ongoing production requiring the SK18-LTP specification, SK18-TP is the recommended replacement from the same manufacturer.

Secondary Substitutes (Similar, Active Status):

B180B-13-F from Diodes Incorporated is an active substitute with matching voltage and current ratings. Forward voltage is lower (790 mV @ 1 A versus 850 mV @ 1 A), and operating temperature range is extended (-65°C ~ 150°C versus -55°C ~ 125°C). This part is suitable for applications where lower forward voltage drop is beneficial and extended temperature operation is required.

B280-13-F from Diodes Incorporated provides 2 A current rating in the same 80 V package. This part is applicable when higher current capacity is needed within the same voltage class. Reverse leakage increases to 7 mA @ 80 V, which may affect applications sensitive to leakage current.

SS28 from onsemi is a 2 A rated part at 80 V with lower reverse leakage (400 µA @ 80 V). However, this part carries "Not For New Designs" status, limiting its suitability for new applications.

Not Recommended:

SK38B/TR13 from Microsemi Corporation is not RoHS3 compliant, disqualifying it from applications requiring RoHS compliance certification.

SK18 from Diotec Semiconductor uses a different package (DO-214AC, SMA) instead of the required DO-214AA (SMB), making it physically incompatible with existing PCB layouts designed for SK18-LTP.

Frequently Asked Questions (FAQ)

Q: Can SK18-TP directly replace SK18-LTP in existing designs?

A: Yes. SK18-TP is a parametric equivalent with identical electrical specifications and package configuration. No circuit modifications are required. The primary difference is product status: SK18-TP is Active while SK18-LTP is Not For New Designs.

Q: What is the difference between B180B-13-F and SK18-LTP?

A: Both parts are rated for 80 V and 1 A in DO-214AA (SMB) packages. B180B-13-F has a lower forward voltage (790 mV versus 850 mV at 1 A) and an extended operating temperature range (-65°C ~ 150°C versus -55°C ~ 125°C). B180B-13-F is from an active product line, making it suitable for new designs.

Q: Can I use B280-13-F or SS28 as replacements for SK18-LTP?

A: B280-13-F and SS28 are rated for 2 A instead of 1 A. They are physically compatible (same DO-214AA, SMB package) and maintain the 80 V voltage rating. These parts are suitable for applications where higher current capacity is acceptable. However, they are not direct equivalents due to the higher current rating and different reverse leakage characteristics.

Q: Why is SK18 from Diotec Semiconductor not recommended?

A: SK18 from Diotec uses a DO-214AC (SMA) package, which is physically different from the DO-214AA (SMB) package required for SK18-LTP. This package difference makes it incompatible with existing PCB layouts and assembly processes designed for SMB components.

Q: Is SK38B/TR13 a suitable substitute?

A: SK38B/TR13 is not RoHS3 compliant, which disqualifies it from applications requiring RoHS compliance certification. Additionally, it is rated for 3 A, exceeding the 1 A requirement of SK18-LTP. Use this part only in applications where RoHS compliance is not mandated and higher current capacity is needed.

Q: What should I consider when selecting between active substitutes?

A: Consider three factors: (1) Forward voltage drop—lower values reduce power dissipation; (2) Operating temperature range—select parts matching or exceeding your application's thermal requirements; (3) Reverse leakage current—critical for applications sensitive to leakage, such as precision analog circuits. All recommended active substitutes maintain the 80 V voltage rating and DO-214AA (SMB) package compatibility.

Q: Are there inventory considerations for part selection?

A: Yes. SK18-TP has 903 units in stock, B180B-13-F has 2921 units, B280-13-F has 16031 units, and SK18 from Diotec has 20815 units. Inventory levels may influence procurement decisions for high-volume production.

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