AS4PK-M3/86A Equivalent & Substitute Parts

Part Overview

The AS4PK-M3/86A is an avalanche diode manufactured by Vishay General Semiconductor - Diodes Division, operating at 800V DC reverse voltage with 2.4A average rectified current. This component belongs to the eSMP® series and is classified as an active product with ROHS3 compliance. The diode is packaged in TO-277A (SMPC) surface mount configuration and is designed for standard recovery applications requiring avalanche protection characteristics.

Equivalent and substitute parts are identified when component availability is limited, supply chain disruptions occur, or design flexibility permits alternative packaging or performance specifications within acceptable electrical parameters.

Substiute Parts

AS4PK-M3/86A

Vishay General Semiconductor - Diodes DivisionIn Stock: 804AS4PK-M3/86A Datasheet

Current PartRFQ

STTH208U

STMicroelectronicsIn Stock: 20394STTH208U Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the AS4PK-M3/86A is determined by the following critical electrical and mechanical parameters:

Voltage Rating Compatibility: The substitute part must maintain a DC reverse voltage rating of 800V or higher to ensure equivalent or superior voltage withstand capability.

Current Rating Compatibility: The substitute part must support a minimum average rectified current of 2.4A. Parts with lower current ratings are not suitable for direct substitution.

Package and Mounting Compatibility: While the primary part uses TO-277A (SMPC) surface mount packaging, substitute parts may utilize alternative surface mount packages (such as SMB/DO-214AA) provided the physical footprint and thermal characteristics are compatible with the application circuit design.

Technology Classification: The AS4PK-M3/86A employs avalanche diode technology with standard recovery characteristics. Substitute parts utilizing standard or fast recovery technology at equivalent voltage and current ratings are acceptable, as both technologies satisfy 800V rectification requirements.

Compliance and Regulatory Status: All substitute parts must maintain ROHS3 compliance and REACH unaffected status to ensure regulatory equivalence.

The STTH208U from STMicroelectronics meets these substitution criteria with matching 800V voltage rating and 2A current rating (within the 2.4A specification), while offering fast recovery technology and SMB surface mount packaging.

Parameter Comparison

Engineering Selection Recommendations

Voltage and Current Ratings: Both the AS4PK-M3/86A and STTH208U are rated for 800V DC reverse voltage, satisfying equivalent voltage withstand requirements. The STTH208U operates at 2.0A average rectified current, which is 0.4A lower than the primary part's 2.4A rating. Selection of the STTH208U is appropriate for applications where the actual circuit current demand does not exceed 2.0A.

Forward Voltage Characteristics: The STTH208U exhibits higher forward voltage (1.65V @ 2A) compared to the AS4PK-M3/86A (962 mV @ 2A). This difference results in increased power dissipation and heat generation in the substitute part. Thermal design verification is necessary when substituting in power-sensitive applications.

Recovery Speed: The STTH208U features fast recovery technology (75 ns) compared to the standard recovery characteristic of the AS4PK-M3/86A (1.8 µs). Fast recovery reduces switching losses and is compatible with applications designed for standard recovery diodes.

Reverse Leakage: The STTH208U demonstrates lower reverse leakage current (5 µA @ 800V) relative to the primary part (10 µA @ 800V), indicating superior reverse blocking performance.

Regulatory Compliance: Both parts maintain ROHS3 compliance, REACH unaffected status, and MSL 1 (Unlimited) moisture sensitivity classification, ensuring equivalent regulatory and environmental qualification.

Package Considerations: The STTH208U uses SMB (DO-214AA) surface mount packaging, which differs from the TO-277A (SMPC) package of the primary part. PCB layout modifications and footprint redesign are required for physical substitution.

Frequently Asked Questions (FAQ)

Q: Can the STTH208U directly replace the AS4PK-M3/86A without circuit modifications?

A: Direct replacement requires verification of three factors: (1) PCB footprint compatibility, as the STTH208U uses SMB packaging versus the TO-277A package of the primary part; (2) thermal design adequacy, given the higher forward voltage of the STTH208U; (3) circuit current demand confirmation that does not exceed the 2.0A rating of the substitute part.

Q: What is the significance of the current rating difference between 2.4A and 2.0A?

A: The AS4PK-M3/86A supports 2.4A average rectified current, while the STTH208U is rated for 2.0A. The substitute part is suitable only for applications where the actual average rectified current remains at or below 2.0A. Exceeding this rating results in component overstress and potential failure.

Q: How does the forward voltage difference affect circuit performance?

A: The STTH208U exhibits 1.65V forward voltage at 2A compared to 962 mV for the AS4PK-M3/86A. This 688 mV difference increases power dissipation in the diode. In high-current or continuous-duty applications, this results in elevated junction temperature and reduced component reliability. Thermal analysis is required to confirm acceptable operating conditions.

Q: Are there packaging considerations for PCB design?

A: Yes. The AS4PK-M3/86A uses TO-277A (SMPC) surface mount packaging, while the STTH208U uses SMB (DO-214AA) packaging. These packages have different footprints, lead configurations, and thermal characteristics. PCB layout redesign is necessary for physical substitution, including pad geometry, trace routing, and thermal via placement.

Q: Do both parts meet the same regulatory and environmental standards?

A: Yes. Both the AS4PK-M3/86A and STTH208U are ROHS3 compliant, REACH unaffected, and classified as MSL 1 (Unlimited) for moisture sensitivity. They are equivalent from a regulatory and environmental qualification perspective.

Q: What is the advantage of the STTH208U's fast recovery characteristic?

A: Fast recovery (75 ns) reduces reverse recovery losses compared to standard recovery (1.8 µs). This characteristic decreases switching losses, reduces electromagnetic interference, and improves efficiency in switching applications. Fast recovery is compatible with circuits designed for standard recovery diodes.

Q: Can the STTH208U be used in applications requiring avalanche protection?

A: The STTH208U is classified as a standard general-purpose diode, not an avalanche diode. The AS4PK-M3/86A is specifically designed with avalanche technology for transient overvoltage protection. If the application requires avalanche protection characteristics, the STTH208U is not a suitable substitute.