S3N Equivalent & Substitute Parts

Part Overview

The S3N is a general-purpose rectifier diode manufactured by onsemi, rated for 1200 V DC reverse voltage and 3 A average rectified current in a Surface Mount SMC (DO-214AB) package. This component is classified as "Not For New Designs," indicating it has been superseded in onsemi's product portfolio. Identifying equivalent substitute parts is necessary for applications requiring continued support, legacy system maintenance, or when the primary part becomes unavailable.

Substiute Parts

S3N

onsemiIn Stock: 18862S3N Datasheet

Current PartRFQ

STTH212S

STMicroelectronicsIn Stock: 20470STTH212S Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the S3N are identified based on the following critical electrical and mechanical parameters:

Voltage Rating Compatibility: The substitute must maintain the 1200 V DC reverse voltage rating to ensure safe operation in the same circuit topology.

Package Compatibility: The substitute must use the DO-214AB (SMC) Surface Mount package to ensure mechanical and thermal compatibility with existing PCB layouts and assembly processes.

Current Rating Consideration: While the S3N is rated for 3 A average rectified current, substitutes with equal or higher current ratings are acceptable. Substitutes with lower current ratings require circuit-level evaluation to confirm adequate thermal and electrical margins.

Recovery Characteristics: Standard recovery (>500 ns) and fast recovery (≤500 ns) diodes are both acceptable substitutes, as recovery speed does not prevent functional substitution in general-purpose rectification applications.

Compliance and Status: Substitutes must maintain RoHS3 compliance and REACH unaffected status to satisfy regulatory requirements equivalent to the original part.

Parameter Comparison

Engineering Selection Recommendations

STTH212S as Substitute for S3N:

The STTH212S from STMicroelectronics is a qualified substitute for the S3N based on matching voltage rating (1200 V), identical package format (DO-214AB, SMC), and equivalent regulatory compliance (RoHS3, REACH unaffected).

Current Rating Differential: The STTH212S is rated for 2 A average rectified current, compared to the S3N's 3 A rating. This represents a 33% reduction in current capacity. Substitution is valid only when circuit load current does not exceed 2 A. Applications requiring the full 3 A capacity of the S3N require alternative substitutes with matching or higher current ratings.

Product Status Advantage: The STTH212S carries an "Active" product status, ensuring continued availability and manufacturer support. The S3N's "Not For New Designs" status indicates limited future availability and no active development support.

Thermal Performance: The STTH212S supports a maximum junction temperature of 175°C, compared to the S3N's 150°C. This provides improved thermal margin in high-temperature operating environments.

Recovery Characteristics: The STTH212S exhibits fast recovery (75 ns) compared to the S3N's standard recovery (2.5 µs). Fast recovery reduces switching losses and electromagnetic interference in rectification circuits.

Frequently Asked Questions (FAQ)

Q: Can the STTH212S directly replace the S3N in all applications?

A: Direct substitution is valid only when the application circuit load current does not exceed 2 A. The STTH212S is rated for 2 A average rectified current, while the S3N is rated for 3 A. If the circuit requires 3 A capacity, alternative substitutes with matching or higher current ratings must be selected.

Q: Are the S3N and STTH212S mechanically compatible?

A: Yes. Both components use the DO-214AB (SMC) Surface Mount package. PCB footprints, solder pad layouts, and thermal characteristics are identical, enabling direct mechanical substitution without PCB redesign.

Q: What is the significance of the different recovery times?

A: The S3N has a reverse recovery time of 2.5 µs (standard recovery), while the STTH212S has 75 ns (fast recovery). Fast recovery reduces switching transients and electromagnetic noise. In general-purpose rectification applications, both recovery characteristics are functionally acceptable. Fast recovery may provide performance benefits in high-frequency or noise-sensitive circuits.

Q: Do both parts meet the same regulatory requirements?

A: Yes. Both the S3N and STTH212S are RoHS3 compliant and REACH unaffected. They satisfy equivalent regulatory requirements for hazardous substance restrictions and environmental compliance.

Q: Why is the S3N marked "Not For New Designs"?

A: This designation indicates that onsemi has discontinued active development and marketing of the S3N. The part remains available from existing inventory but will not receive design updates or long-term support. New designs should incorporate the STTH212S or other active-status alternatives to ensure long-term component availability and manufacturer support.

Q: What is the impact of the forward voltage difference between the two parts?

A: The S3N has a forward voltage of 1.2 V at 3 A, while the STTH212S has 1.75 V at 2 A. The STTH212S exhibits higher forward voltage drop, resulting in increased power dissipation in the diode. Thermal design calculations must account for this difference when substituting in power-sensitive applications.

Q: Are there packaging format differences between the two parts?

A: No. Both parts use identical packaging: DO-214AB (SMC) Surface Mount format. Tape & Reel (TR) and Cut Tape (CT) & Digi-Reel® are supply format options that do not affect component electrical or mechanical characteristics.