SS18 Schottky Diode Equivalent & Substitute Parts

Part Overview

The onsemi SS18 is a surface mount Schottky rectifier diode rated for 80 V DC reverse voltage and 1 A 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. Organizations requiring SS18 functionality for existing applications or legacy system support must identify equivalent alternatives from active product lines that maintain electrical and mechanical compatibility.

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	200	µA @ 80 V
Package / Case	DO-214AC, SMA	—
Mounting Type	Surface Mount	—
Operating Temperature - Junction	-65°C ~ 125°C	°C
Technology	Schottky	—
RoHS Status	ROHS3 Compliant	—
Moisture Sensitivity Level (MSL)	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitution of the SS18 is determined by the following critical electrical and mechanical parameters:

Mandatory Compatibility Criteria:

Voltage - DC Reverse (Vr) rating must equal or exceed 80 V
Current - Average Rectified (Io) must equal or exceed 1 A
Package / Case must be DO-214AC (SMA) for mechanical and thermal compatibility
Mounting Type must be Surface Mount
Technology must be Schottky
RoHS3 compliance required

Acceptable Variation Parameters:

Forward voltage (Vf) may vary within typical Schottky diode ranges
Reverse leakage current may vary
Operating temperature range may exceed the original specification
Capacitance values may differ

Substitute parts are grouped into two categories based on voltage rating alignment:

Category A: 80 V Rated Equivalents — Direct electrical replacements with identical voltage specifications (B180-13-F, B180Q-13-F, SS18-LTP)

Category B: Higher Voltage Rated Alternatives — Parts with voltage ratings exceeding 80 V that provide enhanced margin for overvoltage conditions (B170-13-F at 70 V is not recommended; SS1H9-E3/5AT at 90 V is acceptable for applications with voltage headroom)

Parameter Comparison

Parameter	SS18 (onsemi)	B180-13-F (Diodes Inc.)	B180Q-13-F (Diodes Inc.)	SS18-LTP (MCC)	SS1H9-E3/5AT (Vishay)	B170-13-F (Diodes Inc.)
Voltage - DC Reverse (Vr) (Max)	80 V	80 V	80 V	80 V	90 V	70 V
Current - Average Rectified (Io)	1 A	1 A	1 A	1 A	1 A	1 A
Voltage - Forward (Vf) (Max) @ If	850 mV @ 1 A	790 mV @ 1 A	790 mV @ 1 A	850 mV @ 1 A	770 mV @ 1 A	790 mV @ 1 A
Speed	Fast Recovery ≤ 500ns, > 200mA	Fast Recovery ≤ 500ns, > 200mA	Fast Recovery ≤ 500ns, > 200mA	Fast Recovery ≤ 500ns, > 200mA	Fast Recovery ≤ 500ns, > 200mA	Fast Recovery ≤ 500ns, > 200mA
Current - Reverse Leakage @ Vr	200 µA @ 80 V	500 µA @ 80 V	Not specified	50 µA @ 80 V	1 µA @ 90 V	500 µA @ 70 V
Package / Case	DO-214AC, SMA	DO-214AC, SMA	DO-214AC, SMA	DO-214AC, SMA	DO-214AC, SMA	DO-214AC, SMA
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount
Operating Temperature - Junction	-65°C ~ 125°C	-65°C ~ 150°C	-65°C ~ 155°C	-55°C ~ 150°C	Max 175°C	-65°C ~ 150°C
Product Status	Not For New Designs	Active	Active	Not For New Designs	Active	Active
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Automotive Grade	—	—	AEC-Q101	—	—	—

Engineering Selection Recommendations

Primary Recommendation: B180-13-F (Diodes Incorporated)

The B180-13-F is the optimal direct substitute for the SS18. It provides identical electrical specifications (80 V, 1 A) in the same DO-214AC package with active product status. The lower forward voltage (790 mV vs. 850 mV) reduces power dissipation. Extended operating temperature range (-65°C to 150°C) exceeds the original specification. Inventory availability is substantial (25,200 units).

Secondary Recommendation: B180Q-13-F (Diodes Incorporated)

The B180Q-13-F offers identical electrical ratings with AEC-Q101 automotive qualification. This variant is required for applications subject to automotive reliability standards. Operating temperature extends to 155°C. Inventory is adequate (13,323 units).

Alternative for Enhanced Voltage Margin: SS1H9-E3/5AT (Vishay)

The SS1H9-E3/5AT provides 90 V reverse voltage rating with superior reverse leakage characteristics (1 µA vs. 200 µA). This part is suitable for applications requiring additional overvoltage protection. Active product status and low inventory (1,008 units) should be considered for long-term supply planning.

Not Recommended: B170-13-F (Diodes Incorporated)

The B170-13-F has a 70 V maximum reverse voltage rating, which is below the 80 V specification of the SS18. This part does not meet the mandatory voltage compatibility criterion and introduces risk of component failure under rated operating conditions.

Not Recommended: SS18-LTP (Micro Commercial Co)

While electrically equivalent, the SS18-LTP carries "Not For New Designs" status, identical to the original SS18. This part does not resolve the end-of-life concern and should not be selected for new applications or long-term production.

Frequently Asked Questions (FAQ)

Q: Can the B170-13-F substitute for the SS18 in my application?

A: No. The B170-13-F is rated for 70 V maximum reverse voltage, which is below the SS18 specification of 80 V. Using this part creates risk of diode failure if the circuit operates at or near the rated 80 V condition. The B180-13-F is the correct 80 V equivalent.

Q: What is the difference between B180-13-F and B180Q-13-F?

A: Both parts have identical electrical specifications (80 V, 1 A, DO-214AC package). The B180Q-13-F includes AEC-Q101 automotive qualification and extends the maximum junction temperature to 155°C. Select B180Q-13-F for automotive applications; B180-13-F for general industrial use.

Q: Is the SS1H9-E3/5AT a direct replacement for the SS18?

A: The SS1H9-E3/5AT is electrically compatible with superior performance characteristics (90 V rating, 1 µA reverse leakage). It is not a direct replacement due to higher voltage rating, but it is acceptable for applications where the circuit can accommodate the higher voltage specification. Verify circuit design margins before substitution.

Q: Why is the SS18 marked "Not For New Designs"?

A: This designation indicates the part has reached end-of-life status and the manufacturer no longer recommends it for new product development. Existing inventory may be available, but long-term supply is not guaranteed. Active alternatives such as B180-13-F should be used for new designs.

Q: Are all substitute parts in the same DO-214AC package?

A: Yes. All substitute parts listed are packaged in DO-214AC (SMA), ensuring mechanical and thermal compatibility with the original SS18. No PCB layout modifications are required.

Q: What is the impact of forward voltage differences between the SS18 and substitute parts?

A: The SS18 has a maximum forward voltage of 850 mV at 1 A, while B180-13-F and B180Q-13-F are rated at 790 mV. Lower forward voltage reduces power dissipation and heat generation. This is a beneficial characteristic and does not create compatibility issues. Verify that circuit design does not depend on the higher forward voltage of the original part.

Q: Can I use the SS18-LTP as a substitute?

A: The SS18-LTP is electrically equivalent but carries the same "Not For New Designs" status as the original SS18. It does not resolve supply chain concerns. Use B180-13-F or B180Q-13-F for new applications.

Q: What is the difference in reverse leakage current between these parts?

A: Reverse leakage varies significantly: SS18 (200 µA @ 80 V), B180-13-F (500 µA @ 80 V), SS18-LTP (50 µA @ 80 V), and SS1H9-E3/5AT (1 µA @ 90 V). Lower leakage is generally beneficial for low-power applications. Verify that circuit design tolerates the specified leakage current of the selected substitute.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. All substitute parts listed are RoHS3 compliant and REACH unaffected, matching the environmental compliance of the original SS18.

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