Alpha & Omega Semiconductor Inc. AOI5N40

Overview

AOI5N40 from Alpha & Omega Semiconductor is a 400 V, 4.2 A N-channel enhancement-mode MOSFET in TO-251A (IPAK) package, featuring R_DS(on) ≤ 1.6 Ω at V_GS = 10 V, 100% UIS-tested avalanche robustness, and optimized capacitance profile (C_iss = 331 pF typ, C_rss = 3 pF typ) for offline AC-DC power supplies.

For engineers reviewing the AOI5N40 datasheet, pinout, applications, or equivalent options, key selection criteria include its guaranteed unclamped inductive switching capability (E_AS = 86 mJ), low gate charge (Q_g = 6.9 nC typ), thermal resistance R_θJC = 1.6 °C/W, and suitability for flyback and PFC stages operating up to 150 °C junction temperature.

Technical Context

The AOI5N40 employs Alpha & Omega's high-voltage trench MOSFET process, delivering stable R_DS(on) over temperature (±20% drift from −50 °C to 150 °C) and tightly controlled V_GS(th) (3.4–4.5 V). Its low Crss/Ciss ratio (≈0.9%) minimizes Miller-induced turn-off delay in hard-switched topologies.

Designed for primary-side switching in universal-input offline converters, it supports continuous ID = 4.2 A at T_C = 25 °C with derating to 2.8 A at T_C = 100 °C, and withstands repetitive avalanche stress up to I_AR = 43 A and E_AR = 78 mJ under defined test conditions.

Key Specifications

Pinout & Package

AOI5N40 is housed in TO-251A (IPAK) package with gull-wing leads, offering improved thermal performance over DPAK while maintaining compatibility with standard SMT reflow profiles. The exposed drain pad on the bottom surface provides low-inductance, high-current path and direct thermal conduction to PCB copper.

Key Features

Applications

Equivalent & Alternatives

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

Compared with STP4NK40ZFP and IRF640NPBF, the AOI5N40 delivers superior system-level efficiency and reliability in 400 V primary-side switching through its lower R_DS(on), lower Q_g, and factory-verified avalanche capability-enabling simpler, more compact, and more robust offline power designs.

Availability

AOI5N40 is available at Aetrix Electronics and suitable for offline flyback adapters, active PFC stages, and industrial AC-DC modules requiring stable component supply, long-term lifecycle support, and traceable sourcing for production ramp-up.

Supply support for AOI5N40 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 AOI5N40 belongs to AOS's high-voltage trench MOSFET product line, engineered specifically for rugged, high-efficiency AC-DC power supplies operating across universal input ranges and extended temperature environments.

FAQ

What is the maximum continuous drain current rating for AOI5N40 at 100°C case temperature?

The AOI5N40 supports continuous drain current of 2.8 A at T_C = 100 °C, per its absolute maximum ratings table. This derating reflects thermal limits imposed by the TO-251A package's R_θJC = 1.6 °C/W and maximum junction temperature of 150 °C. At T_C = 25 °C, the rated I_D is 4.2 A. Designers must verify PCB copper area and heatsinking to maintain T_C ≤ 100 °C under full-load conditions for AOI5N40.

Does AOI5N40 have a specified avalanche energy rating, and how is it tested?

Yes, AOI5N40 is 100% tested for unclamped inductive switching (UIS) with single-pulse avalanche energy E_AS = 86 mJ (L = 60 mH, I_AS = 1.7 A, V_DD = 150 V, R_G = 10 Ω, starting T_J = 25 °C). Repetitive avalanche energy E_AR is rated at 78 mJ. These values are measured per JEDEC JESD24-11 and documented in the datasheet's Absolute Maximum Ratings section-no external qualification is needed for AOI5N40.

What is the gate threshold voltage range for AOI5N40, and why does it matter in circuit design?

The AOI5N40 has a gate threshold voltage V_GS(th) range of 3.4–4.5 V at T_J = 25 °C. This tight distribution ensures consistent turn-on behavior across production lots and temperature, critical for reliable operation in QR flyback controllers and synchronous rectifier drivers where precise gate timing prevents shoot-through. Designers should avoid driving the gate near this threshold; 10 V is recommended for full enhancement and low R_DS(on) in AOI5N40.

Can AOI5N40 be used as a direct replacement for AOD5N40 in existing designs?

No-AOI5N40 and AOD5N40 share identical electrical specifications but differ in package: AOI5N40 uses TO-251A (IPAK), while AOD5N40 uses TO-252 (DPAK). Though both have three pins in G-S-D order, their land patterns, thermal pad geometry, and mechanical outlines are incompatible. PCB redesign is required to swap AOI5N40 into an AOD5N40 footprint. Always verify mechanical fit and thermal performance when substituting AOI5N40.

What are the key thermal parameters that impact AOI5N40's power dissipation in a real PCB layout?

AOI5N40's power dissipation is governed primarily by R_θJC = 1.6 °C/W (junction-to-case), R_θCA = 55 °C/W (junction-to-ambient on 1 in² 2 oz Cu FR-4), and maximum T_J = 150 °C. In practice, effective heat transfer depends on solder coverage of the exposed drain pad, thermal via count under the pad, and heatsink interface quality. For 3 W dissipation, a well-designed AOI5N40 layout achieves ΔT_J-C ≈ 4.8 °C-far below thermal shutdown thresholds.