Alpha & Omega Semiconductor Inc. AOT5N50

Overview

AOT5N50 from Alpha & Omega Semiconductor is a 500V, 5A N-Channel enhancement-mode MOSFET in TO-220F package, optimized for offline AC-DC power supplies. It delivers R_DS(on) ≤ 1.5 Ω at V_GS = 10 V, 100% UIS-tested avalanche ruggedness, and low C_iss/C_rss for high-efficiency flyback and SMPS designs.

For engineers reviewing the AOT5N50 datasheet, pinout, applications, or equivalent options, key selection criteria include its guaranteed single-pulse avalanche energy (E_AS = 203 mJ), thermal resistance R_θJC = 1.2 °C/W, and gate charge Q_g = 19 nC - critical for hard-switched PFC and adapter designs requiring robustness and fast switching.

Technical Context

The AOT5N50 employs an advanced high-voltage MOSFET process targeting AC-DC primary-side switching. Its 500 V BVDSS rating with 0.55 V/°C temperature coefficient ensures stable breakdown across -55°C to 150°C junction range, while 100% R_g testing guarantees consistent gate drive behavior.

Designed for unclamped inductive switching (UIS) reliability, it supports repetitive avalanche operation (I_AR = 101 A, E_AR = 3.3 mJ) and features low reverse recovery charge (Q_rr = 1.6 mC) and time (t_rr = 199 ns) - enabling reduced diode stress and snubber losses in discontinuous conduction mode (DCM) topologies.

Key Specifications

Pinout & Package

Package: TO-220F (full-pack, isolated tab). Tab is electrically connected to drain; mounting screw provides thermal path without electrical isolation unless insulated hardware is used.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar N-Channel MOSFET applications.

Compared with STP5NK50ZFP and IRFBC40APBF, the AOT5N50 offers superior thermal resistance (R_θJC = 1.2 °C/W vs. 1.6–2.0 °C/W), tighter R_DS(on) distribution, and factory-verified UIS performance - making it optimal for compact, thermally constrained, and safety-certified AC-DC designs.

Availability

AOT5N50 is available at Aetrix Electronics and suitable for adapter power supplies, flyback converters, industrial AC-DC modules, and UPS input stages requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for AOT5N50 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 management.

The AOT5N50 belongs to AOS's high-voltage discrete MOSFET product line, engineered specifically for robust, high-efficiency offline AC-DC power supplies operating up to 100 W with enhanced avalanche reliability and thermal performance.

FAQ

What is the maximum continuous drain current rating for the AOT5N50 at 100°C case temperature?

The AOT5N50 supports 35.0 A pulsed drain current (I_DM) but its continuous drain current (I_D) is thermally limited. At T_C = 100°C, the derated continuous current is approximately 3.3 A - derived from the 5 A rating at 25°C and the linear derating curve in Figure 11, where current drops to 3.3 A at 100°C case temperature. This value ensures junction temperature remains ≤150°C. The AOT5N50 must be heatsinked accordingly for sustained operation.

Does the AOT5N50 have a fully isolated package, and how does that affect heatsink mounting?

The AOT5N50 uses a TO-220F (full-pack) package where the metal tab is electrically connected to the drain terminal and thermally conductive. It is not electrically isolated - mounting directly to a grounded heatsink creates a short circuit unless an insulating pad and shoulder washer are used. The R_θJC = 1.2 °C/W rating assumes direct metal-to-metal contact; adding insulation increases thermal resistance by ~0.5–1.0 °C/W depending on material. Always verify isolation requirements in the AOT5N50 system-level layout.

How does the AOT5N50's body diode performance compare to standard MOSFETs in quasi-resonant converters?

The AOT5N50 features a fast, low-loss body diode with t_rr = 199 ns and Q_rr = 1.6 mC at I_F = 5 A, dI/dt = 100 A/ms - significantly better than generic 500 V MOSFETs (typically t_rr > 300 ns). This reduces reverse recovery loss and EMI in QR flyback designs. Its V_SD = 1.0 V typ also lowers forward conduction loss during dead-time conduction. These characteristics make the AOT5N50 especially effective in high-frequency, high-efficiency QR converters where body diode behavior dominates light-load efficiency.

Is the AOT5N50 suitable for use in automotive power supplies?

The AOT5N50 is not AEC-Q101 qualified and is not recommended for automotive power supplies. Its specified junction temperature range is -55°C to +150°C, but it lacks automotive-grade screening, PPAP documentation, and guaranteed lot traceability required for automotive applications. While it may function in non-safety-critical 12 V auxiliary circuits, AOS explicitly states that use in life-support or automotive systems is unauthorized. For automotive-grade alternatives, consult AOS's AUIRF series or other AEC-Q101-compliant 500 V MOSFETs.

What gate voltage is required to fully enhance the AOT5N50, and what happens below that threshold?

The AOT5N50 has a gate threshold voltage V_GS(th) of 3.5–4.5 V (typ 4.1 V), but full enhancement - defined as achieving R_DS(on) ≤ 1.5 Ω - requires V_GS ≥ 10 V per datasheet test conditions. Below 10 V, R_DS(on) rises sharply (e.g., ~3.5 Ω at V_GS = 8 V), increasing conduction loss and thermal stress. Driving the AOT5N50 with only 5 V logic-level signals results in partial turn-on and potential thermal runaway. Always use a dedicated gate driver or level-shifter to ensure stable 10–15 V gate bias for reliable AOT5N50 operation.