Taiwan Semiconductor Corporation SK35B

Overview

SK35B from Taiwan Semiconductor is a 3A, 50V Schottky barrier surface-mount rectifier in DO-214AA (SMB) package, featuring low forward voltage (0.75 V max at 3 A, 25°C), high surge current capability (70 A), and junction temperature rating up to +150°C. It serves as a primary output rectifier in compact AC/DC adapters and DC/DC converters where efficiency and thermal robustness are critical.

For engineers reviewing the SK35B datasheet, SK35B pinout, SK35B application, or SK35B equivalent, key selection criteria include its 50 V repetitive peak reverse voltage, 100 µA max reverse leakage at 25°C, 23°C/W junction-to-lead thermal resistance, and compatibility with automated SMT placement per J-STD-020 Level 1 moisture sensitivity.

Technical Context

The SK35B implements a single-die Schottky junction optimized for low conduction loss in medium-voltage switching power supplies. Its 50 V V_RRM, 70 A I_FSM, and 10,000 V/µs dV/dt rating support reliable operation under transient overvoltage and high di/dt conditions typical in flyback and buck-derived topologies.

Thermally, the device uses a DO-214AA (SMB) molded plastic case with matte tin-plated leads and UL 94V-0 rated compound. Its R_θJL of 23°C/W enables direct heat transfer to PCB copper, while R_θJA of 63°C/W reflects standard JEDEC 2s2p board conditions - critical for thermal derating in enclosed adapter designs.

Key Specifications

Pinout & Package

Package: DO-214AA (SMB), surface-mount, single-anode/single-cathode configuration. Cathode indicated by molded band. Matte tin-plated leads, J-STD-002 solderable, JESD 201 Class 2 whisker compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SS35 and SB350, the SK35B offers a balanced trade-off: lower leakage than SB350 (100 µA vs. 200 µA) and better thermal resistance than SS35 (23°C/W vs. 30°C/W junction-to-lead), making it optimal for thermally constrained, medium-power adapter designs requiring consistent efficiency across temperature.

Availability

SK35B is available at Aetrix Electronics and suitable for AC/DC adapters, LED drivers, and industrial DC/DC converters requiring stable component supply, long-term lifecycle support, and RoHS-compliant sourcing.

Supply support for SK35B 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, specializing in power rectifiers, TVS devices, and MOSFETs for industrial and consumer markets.

The SK32B–SK320B series was designed specifically for high-efficiency, surface-mount secondary-side rectification in compact switching power supplies - emphasizing low V_F, robust surge handling, and manufacturability in automated SMT lines.

FAQ

What is the maximum repetitive peak reverse voltage (V_RRM) for the SK35B?

The SK35B has a maximum repetitive peak reverse voltage (V_RRM) of 50 V, as confirmed in the Absolute Maximum Ratings table of the P2212 datasheet. This rating defines the highest reverse voltage the device can block continuously without breakdown and is strictly applicable to the SK35B variant - not extrapolated from adjacent SK3xB part numbers. Operating above 50 V risks irreversible avalanche failure.

Does the SK35B have a specified forward voltage (V_F) at elevated junction temperatures?

Yes, the SK35B's forward voltage is characterized up to +150°C. While the datasheet specifies V_F ≤ 0.75 V at 3 A and 25°C, Figure 8 shows typical V_F remains below 0.9 V even at 125°C and 3 A. This behavior is intrinsic to its Schottky architecture and directly supports thermal design in enclosed power supplies where T_J routinely exceeds 100°C.

Is the SK35B suitable for use in USB Power Delivery (PD) 3.0 applications?

Yes, the SK35B is suitable for USB PD 3.0 secondary-side rectification, particularly in 20 V output stages. Its 50 V V_RRM, 100 µA reverse leakage at 25°C, and 70 A surge rating meet the voltage margin, efficiency, and reliability demands of PD-compliant 30 W adapters. The DO-214AA package also aligns with space-constrained PD module layouts.

What is the moisture sensitivity level (MSL) of the SK35B, and does it require baking before reflow?

The SK35B is rated MSL Level 1 per J-STD-020, meaning it has unlimited floor life and requires no pre-reflow baking. This is explicitly stated in the Features section of the P2212 datasheet and verified by its matte tin-plated leads and J-STD-002 solderability. MSL Level 1 simplifies SMT line integration and eliminates moisture-related popcorning risk.

How does the SK35B's thermal resistance compare to similar Schottky rectifiers in DO-214AA packages?

The SK35B has a junction-to-lead thermal resistance (R_θJL) of 23°C/W, measured per standard test conditions. This value is 3–5°C/W lower than typical industry benchmarks for DO-214AA Schottky rectifiers (e.g., 26–28°C/W), indicating superior internal thermal path design. That advantage translates directly to ~5–8°C lower junction temperature under identical 3 A DC load conditions on the same PCB.