Taiwan Semiconductor Corporation SK39B

Overview

SK39B from Taiwan Semiconductor is a 3A, 90V Schottky barrier surface-mount rectifier in DO-214AA (SMB) package, designed for high-efficiency DC/DC conversion with low forward voltage (0.85 V at 3 A, 25°C), high surge current capability (70 A), and junction temperature up to +150°C. It serves as the primary output rectifier in compact AC/DC adapters and offline SMPS.

For engineers reviewing the SK39B datasheet, SK39B pinout, SK39B application, or SK39B equivalent, key selection criteria include its 90 V repetitive peak reverse voltage, 0.85 V forward voltage at rated current, 100 µA reverse leakage at 25°C, thermal resistance of 23°C/W (junction-to-lead), and DO-214AA mechanical compatibility with automated SMT assembly.

Technical Context

The SK39B implements a single-die Schottky junction optimized for low conduction loss in medium-voltage switching power supplies. Its 90 V V_RRM, 70 A I_FSM, and 10,000 V/µs dV/dt rating support robust operation under transient overvoltage and line surges typical in universal-input adapters.

Thermal performance is defined by R_θJL = 23°C/W and R_θJA = 63°C/W, enabling reliable 3 A continuous conduction at ambient temperatures up to +85°C with standard PCB copper area. Reverse leakage remains ≤100 µA at 25°C and ≤2 mA at 125°C, ensuring stable no-load regulation.

Key Specifications

Pinout & Package

DO-214AA (SMB) surface-mount package with cathode-indicated band; matte tin-plated leads compliant with J-STD-002 solderability and JESD201 Class 2 whisker resistance.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar Schottky rectifier applications.

Compared with SS39 and SB390, the SK39B offers tighter reverse leakage control (100 µA vs. 200 µA) and guaranteed 0.85 V V_F maximum-critical for meeting CoC Tier 2 and EU ErP Lot 6 standby power limits in adapter designs.

Availability

SK39B is available at Aetrix Electronics and suitable for AC/DC adapters, LED drivers, and industrial SMPS requiring stable component supply, consistent parametric performance, and long-term manufacturing continuity.

Supply support for SK39B includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Taiwan Semiconductor Corporation (TSC) is a vertically integrated analog and discrete semiconductor manufacturer headquartered in Hsinchu, Taiwan, serving global power electronics markets since 1979.

The SK32B–SK320B family was engineered specifically for high-volume, cost-sensitive switching power supplies-emphasizing manufacturability, thermal robustness, and compliance with international environmental standards.

FAQ

What is the maximum junction temperature rating for SK39B?

The SK39B has a maximum junction temperature (T_J) rating of +150°C, verified per absolute maximum ratings table in the official Taiwan Semiconductor datasheet P2212. This allows sustained 3 A operation in thermally constrained enclosures such as sealed LED drivers or compact USB PD chargers. The SK39B must be mounted on adequate PCB copper area to maintain T_J ≤150°C under worst-case ambient and load conditions.

Does SK39B meet RoHS and halogen-free requirements?

Yes, the SK39B is RoHS compliant and halogen-free per IEC 61249-2-21, as confirmed in the "Features" section of the Taiwan Semiconductor datasheet P2212. The molding compound is UL 94V-0 rated, and terminals are matte tin-plated to J-STD-002 standards-ensuring full regulatory alignment for CE, UKCA, and China RoHS-marked end products.

What is the forward voltage specification for SK39B at 3 A and 25°C?

The SK39B has a maximum forward voltage (V_F) of 0.85 V at I_F = 3 A and T_J = 25°C, per the "ELECTRICAL SPECIFICATIONS" table in datasheet P2212. This value is measured under pulse test conditions (PW = 0.3 ms), representing worst-case conduction loss during steady-state operation. Typical V_F is lower, but design margins should use the 0.85 V max value.

Is SK39B pin-compatible with other parts in the SK3xB series?

Yes, all SK3xB variants-including SK32B through SK320B-share identical DO-214AA (SMB) package dimensions, anode/cathode terminal configuration, and polarity marking. The SK39B can be substituted within the same footprint for voltage upgrades (e.g., replacing SK36B) or downgrades (e.g., replacing SK310B), provided V_RRM and V_F requirements are met for the target application.

What is the reverse leakage current of SK39B at 125°C?

At T_J = 125°C and rated reverse voltage (90 V), the SK39B exhibits a maximum reverse leakage current (I_R) of 2 mA, as specified in the "ELECTRICAL SPECIFICATIONS" table of datasheet P2212. This value is critical for light-load regulation and standby power budgeting in energy-efficient adapters complying with DOE Level VI or EU ErP Lot 6 standards.