Alpha & Omega Semiconductor Inc. AOT8N50

Overview

AOT8N50 from Alpha & Omega Semiconductor is a 500V, 9A N-channel enhancement-mode MOSFET in TO-220F package, featuring R_DS(on) ≤ 0.85 Ω at V_GS = 10 V, 100% UIS-tested avalanche robustness, and optimized for offline AC-DC power supplies such as adapters and open-frame SMPS.

For engineers reviewing the AOT8N50 datasheet, pinout, applications, or equivalent options, key selection criteria include its guaranteed single-pulse avalanche energy (E_AS = 307 mJ), low C_iss (typ. 868 pF), gate charge (Q_g = 28 nC), and thermal resistance R_θJC = 0.65 °C/W - all critical for high-efficiency, thermally constrained flyback and LLC designs.

Technical Context

The AOT8N50 employs Alpha & Omega's advanced high-voltage trench MOSFET process to achieve low conduction loss and fast switching with controlled dv/dt immunity. Its 600V BVDSS rating at TJ = 150°C ensures margin under surge conditions, while 100% R_g testing guarantees gate drive consistency across production lots.

Designed for hard-switched topologies, it delivers stable R_DS(on) over temperature (TC = 0.56 V/°C) and supports body-diode operation with t_rr = 247 ns and Q_rr = 2.6 mC at IF = 8 A, dI/dt = 100 A/ms - enabling reliable synchronous rectification or freewheeling in continuous-conduction-mode converters.

Key Specifications

Pinout & Package

Package: TO-220F (full-pack, insulated tab), thermally enhanced variant of TO-220 with electrically isolated drain tab rated for 2500 V_RMS isolation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar N-channel high-voltage MOSFET applications.

Compared with STP8NK50ZFP and IPP60R099C7, the AOT8N50 delivers optimal balance of avalanche robustness, thermal performance (R_θJC = 0.65 °C/W), and gate drive simplicity (Q_g = 28 nC) for mid-power offline converters - avoiding both under-specification and unnecessary cost premium.

Availability

AOT8N50 is available at Aetrix Electronics and suitable for adapter power supplies, industrial AC-DC modules, and LED drivers requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.

Supply support for AOT8N50 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

Alpha & Omega Semiconductor (AOS) is a fabless power semiconductor company specializing in high-performance MOSFETs, IGBTs, and power ICs for power conversion and motor control.

The AOT8N50 belongs to AOS's "AlphaMOS" high-voltage discrete portfolio, engineered specifically for rugged, high-efficiency offline AC-DC power stages in consumer and industrial applications.

FAQ

What is the maximum continuous drain current rating for AOT8N50 at case temperature of 100°C?

The AOT8N50 supports 5 A continuous drain current at T_C = 100°C, as specified in the Absolute Maximum Ratings table and confirmed by the derating curve in Figure 11. This value reflects thermal limitation due to R_θJC = 0.65 °C/W and T_J(MAX) = 150°C. At T_C = 25°C, the rating is 9 A. Designers must verify heatsink sizing using actual board-level thermal resistance to ensure AOT8N50 remains within safe operating area.

Does AOT8N50 have an electrically isolated package, and what is its isolation rating?

Yes, the AOT8N50 uses the TO-220F (full-pack) package with an electrically isolated drain tab. Per AOS documentation, this isolation is rated for 2500 V_RMS for 1 minute, enabling direct mounting to grounded heatsinks without additional insulation. This feature simplifies thermal design and enhances safety compliance in Class II power supplies - a key differentiator versus standard TO-220 variants. The AOT8N50 datasheet confirms this construction on Page 1 top-view diagram.

What is the typical gate threshold voltage range for AOT8N50, and how does it affect drive circuit design?

The AOT8N50 has a V_GS(th) range of 3.4 V to 4.5 V at T_J = 25°C, per Electrical Characteristics table. This relatively tight threshold window ensures consistent turn-on behavior across units and temperatures, reducing need for overdrive. Designers should apply ≥ 10 V gate drive to achieve rated R_DS(on); lower voltages increase conduction loss. The AOT8N50's g_FS = 10 S further supports clean switching with moderate gate resistor values (e.g., 10–22 Ω).

How is the avalanche capability of AOT8N50 verified, and what test conditions apply?

The AOT8N50 undergoes 100% unclamped inductive switching (UIS) testing per JEDEC JESD22-A110. Each unit is stressed with L = 60 mH, I_AS = 3.2 A, V_DD = 150 V, R_G = 25 Ω, and starting T_J = 25°C, achieving E_AS = 307 mJ minimum. This validation ensures reliability in transformer leakage energy absorption during hard-switching transitions - a critical requirement for AOT8N50 in flyback and forward converter primary switches.

Can AOT8N50 be used in place of AOTF8N50, and what are the key mechanical and thermal differences?

No, AOT8N50 and AOTF8N50 are not interchangeable without layout review. While electrically identical, AOT8N50 uses TO-220F (isolated tab), whereas AOTF8N50 uses standard TO-220 (non-isolated tab). Their thermal resistances differ significantly: AOT8N50 has R_θJC = 0.65 °C/W, while AOTF8N50 is 3.25 °C/W. Substituting AOT8N50 into an AOTF8N50 design may cause overcooling or mechanical fit issues; substituting AOTF8N50 into an AOT8N50 design risks electrical shorting and thermal runaway. Always match package type to schematic and footprint.