SS18-LTP Schottky Diode Equivalent & Substitute Parts

Part Overview

The SS18-LTP is a surface mount Schottky rectifier diode manufactured by Micro Commercial Co, rated for 80V DC reverse voltage and 1A average rectified current in a DO-214AC (SMA) package. This component is classified as "Not For New Designs," indicating it has reached end-of-life status. Identifying equivalent and substitute parts is necessary for ongoing maintenance, repair, and legacy system support where the original part is no longer readily available or where design flexibility permits component substitution within specified electrical and mechanical parameters.

Key Parameters

Parameter	Value	Unit
Voltage - DC Reverse (Vr) (Max)	80	V
Current - Average Rectified (Io)	1	A
Voltage - Forward (Vf) (Max) @ If	850 mV @ 1 A	mV
Speed	Fast Recovery ≤ 500ns, > 200mA (Io)	ns
Current - Reverse Leakage @ Vr	50	µA @ 80 V
Package / Case	DO-214AC, SMA	—
Mounting Type	Surface Mount	—
Operating Temperature - Junction	-55°C ~ 150°C	°C
Technology	Schottky	—
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitution of the SS18-LTP is determined by strict equivalence across the following critical parameters:

Electrical Equivalence Criteria:

Voltage - DC Reverse (Vr) (Max): 80V
Current - Average Rectified (Io): 1A
Voltage - Forward (Vf) (Max) @ If: 850 mV @ 1A
Speed: Fast Recovery ≤ 500ns, > 200mA (Io)
Technology: Schottky

Mechanical Equivalence Criteria:

Package / Case: DO-214AC (SMA)
Mounting Type: Surface Mount

Compliance Criteria:

RoHS Status: ROHS3 Compliant
Moisture Sensitivity Level (MSL): 1 (Unlimited)

Substitute parts identified in this reference maintain electrical performance within the specified parameters and are housed in identical or functionally equivalent surface mount packages. Reverse leakage current and capacitance specifications may vary within acceptable engineering tolerances for this component category.

Parameter Comparison

Parameter	SS18-LTP (Micro Commercial Co)	SS18 (onsemi)	SS18W_R1_00001 (Panjit International Inc.)
Voltage - DC Reverse (Vr) (Max)	80 V	80 V	80 V
Current - Average Rectified (Io)	1 A	1 A	1 A
Voltage - Forward (Vf) (Max) @ If	850 mV @ 1 A	850 mV @ 1 A	850 mV @ 1 A
Speed	Fast Recovery ≤ 500ns, > 200mA (Io)	Fast Recovery ≤ 500ns, > 200mA (Io)	Fast Recovery ≤ 500ns, > 200mA (Io)
Current - Reverse Leakage @ Vr	50 µA @ 80 V	200 µA @ 80 V	500 µA @ 80 V
Package / Case	DO-214AC, SMA	DO-214AC, SMA	DO-214AC, SMA
Mounting Type	Surface Mount	Surface Mount	Surface Mount
Operating Temperature - Junction	-55°C ~ 150°C	-65°C ~ 125°C	-55°C ~ 150°C
Technology	Schottky	Schottky	Schottky
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Product Status	Not For New Designs	Not For New Designs	Active

Engineering Selection Recommendations

SS18 (onsemi): This part maintains full electrical equivalence to the SS18-LTP across all critical parameters including reverse voltage, forward current, and switching speed. Both components share "Not For New Designs" status, indicating similar lifecycle positioning. The onsemi SS18 operates across a narrower junction temperature range (-65°C to 125°C) compared to the original part (-55°C to 150°C). Reverse leakage current is elevated at 200 µA versus 50 µA in the original specification. This substitute is suitable for applications where the reduced temperature range and increased leakage current remain within system design margins.

SS18W_R1_00001 (Panjit International Inc.): This part achieves full electrical equivalence across all critical parameters and maintains the same junction temperature range as the original SS18-LTP (-55°C to 150°C). The SS18W_R1_00001 carries "Active" product status, indicating ongoing manufacturer support and availability. Reverse leakage current is specified at 500 µA, representing the highest leakage among the three options. This substitute is recommended for new applications and ongoing production where component availability and manufacturer support are priorities, provided that the elevated reverse leakage current is acceptable within the circuit design.

Both substitute parts are ROHS3 compliant, carry MSL 1 (Unlimited) moisture sensitivity rating, and are housed in identical DO-214AC (SMA) surface mount packages, ensuring mechanical and thermal compatibility with existing PCB layouts.

Frequently Asked Questions (FAQ)

Q: Can the SS18 (onsemi) be used as a direct replacement for the SS18-LTP in all applications?

A: The SS18 maintains electrical equivalence across reverse voltage (80V), forward current (1A), and switching speed specifications. However, the operating temperature range differs: SS18 operates from -65°C to 125°C while SS18-LTP operates from -55°C to 150°C. Substitution is valid only if the application's junction temperature requirements fall within the -65°C to 125°C window. Additionally, reverse leakage current is 200 µA in the SS18 versus 50 µA in the original; circuit designs sensitive to leakage current must account for this difference.

Q: What is the primary advantage of the SS18W_R1_00001 over the other substitutes?

A: The SS18W_R1_00001 carries "Active" product status, indicating current manufacturer production and ongoing availability. It also matches the original SS18-LTP operating temperature range (-55°C to 150°C). For new designs and long-term production requirements, this part offers superior supply chain continuity. The trade-off is elevated reverse leakage current at 500 µA.

Q: Are all three parts mechanically interchangeable?

A: Yes. All three parts—SS18-LTP, SS18, and SS18W_R1_00001—are housed in DO-214AC (SMA) surface mount packages with identical pin configurations and footprints. They are mechanically and thermally interchangeable on PCB layouts designed for the DO-214AC package.

Q: How do reverse leakage current differences affect circuit performance?

A: Reverse leakage current represents unwanted current flow when the diode is reverse-biased. The SS18-LTP specifies 50 µA, the SS18 specifies 200 µA, and the SS18W_R1_00001 specifies 500 µA at 80V reverse bias. In high-impedance circuits or precision analog applications, elevated leakage may introduce measurable error. In standard rectification and switching applications, these differences are typically negligible. Circuit designers must evaluate leakage current impact based on specific application requirements.

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

A: The SS18W_R1_00001 is the recommended choice for new designs due to its "Active" product status, ensuring long-term availability and manufacturer support. It maintains full electrical equivalence and matches the original temperature range. The onsemi SS18, while electrically equivalent, carries "Not For New Designs" status and should be reserved for legacy system support and repair applications.

Q: Are there any compliance or certification differences between the three parts?

A: All three parts are ROHS3 compliant, carry MSL 1 (Unlimited) moisture sensitivity rating, and are REACH unaffected. Compliance and certification status are equivalent across all three options.

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