Alpha & Omega Semiconductor Inc. AOI8N25

Overview

AOI8N25 from Alpha & Omega Semiconductor is a 250V, 8A N-Channel enhancement-mode MOSFET in TO-251A (IPAK) package, featuring R_DS(on) < 0.56 Ω at V_GS = 10 V, 100% UIS-tested avalanche capability, and optimized for high-efficiency offline AC-DC power supplies including boost converters and synchronous rectifiers.

For engineers reviewing the AOI8N25 datasheet, pinout, applications, or equivalent options, key selection criteria include its 250V V_DS, 8A continuous drain current at T_C = 25°C, guaranteed avalanche energy of 132 mJ, low gate charge (7.2 nC typical), and thermal resistance R_θJC = 1.6°C/W - all critical for thermally constrained industrial and LED backlighting designs.

Technical Context

The AOI8N25 employs Alpha & Omega's advanced high-voltage trench MOSFET process to achieve robust unclamped inductive switching (UIS) performance and low dynamic losses. Its 3.1–4.3 V gate threshold voltage ensures reliable turn-on with standard 5 V or 10 V gate drivers, while Crss = 3.2 pF (typical) minimizes Miller-induced shoot-through risk in hard-switched topologies.

Designed specifically for offline primary-side switching and secondary-side synchronous rectification, the device delivers stable R_DS(on) over temperature (±20% drift from −55°C to 125°C) and supports fast switching with t_D(on) = 14 ns and t_f = 12 ns under standardized 25 Ω gate drive conditions.

Key Specifications

Pinout & Package

AOI8N25 is housed in a TO-251A (IPAK) surface-mount package with gull-wing leads, featuring isolated tab (drain-connected) and optimized thermal path from junction to case.

Key Features

Applications

Equivalent & Alternatives

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

Compared with STP8NK25ZFP and IRF640NPBF, the AOI8N25 provides superior combination of voltage rating, surface-mount form factor, and factory-validated UIS capability - making it the preferred choice for modern compact, high-reliability AC-DC and DC-DC converters where thermal and layout constraints preclude through-hole solutions.

Availability

AOI8N25 is available at Aetrix Electronics and suitable for boost converters, synchronous rectifiers, LED backlight drivers, and industrial DC-DC converters requiring stable component supply, consistent parametric performance, and long-term manufacturing continuity.

Supply support for AOI8N25 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 AOI8N25 belongs to AOS's high-voltage trench MOSFET product line, engineered for robustness and efficiency in offline AC-DC power supplies, LED drivers, and industrial power systems.

FAQ

What is the maximum junction temperature rating for AOI8N25?

The AOI8N25 has a maximum junction temperature (T_J) rating of 150°C, validated across its full operating range and reflected in its thermal derating curves (Fig. 12–13). This rating supports reliable operation in sealed industrial enclosures and high-ambient LED driver applications. The device's R_θJC = 1.6°C/W enables effective heat transfer to external heatsinks or PCB copper layers, ensuring AOI8N25 maintains safe thermal margins even at full 8 A load under worst-case ambient conditions.

Does AOI8N25 support logic-level gate drive?

The AOI8N25 features a gate threshold voltage (V_GS(th)) of 3.1–4.3 V, allowing turn-on with standard 5 V logic-level drivers, though full enhancement and minimum R_DS(on) require V_GS ≥ 10 V. Its transconductance (g_FS) = 5 S ensures strong gate control, and the 7.2 nC total gate charge enables efficient switching at 100–300 kHz. For AOI8N25 designs using 3.3 V microcontrollers, a gate driver IC is recommended to ensure robust turn-on and prevent partial conduction losses.

Is AOI8N25 suitable for synchronous rectification in LLC resonant converters?

Yes, AOI8N25 is well-suited for synchronous rectification in LLC resonant converters due to its fast body diode recovery (t_rr = 77 ns), low Crss (3.2 pF), and tight Q_gd/Q_gs ratio (1.5 nC / 2.0 nC), which enable precise zero-voltage switching (ZVS) alignment. Its 250 V rating accommodates peak resonant voltages in 24 V and 48 V output designs, and the TO-251A package allows dense layout with minimal parasitic inductance - all confirmed in AOI8N25 application notes for telecom and server power supplies.

What is the avalanche energy rating of AOI8N25, and how is it tested?

The AOI8N25 is rated for 132 mJ single-pulsed avalanche energy (E_AS) under test condition L = 60 mH, I_AS = 2.1 A, V_DD = 150 V, R_G = 10 Ω, starting at T_J = 25°C. Crucially, 100% of AOI8N25 units undergo production UIS testing - not just sampling - ensuring every device meets this specification. This eliminates statistical uncertainty in high-reliability applications such as industrial motor drives and medical power supplies where overvoltage transients are routine.

How does the thermal performance of AOI8N25 compare between TO-251A and TO-252 packages?

The AOI8N25 in TO-251A (IPAK) shares identical die and electrical specs with the AOD8N25 in TO-252 (DPAK), but exhibits slightly higher R_θJA (55°C/W vs. 45°C/W for TO-252 on same 1 in² 2 oz copper board) due to reduced pad area. However, its R_θJC remains identical at 1.6°C/W, meaning thermal performance under heatsink mounting is equivalent. For AOI8N25, optimal thermal design uses soldered tab-to-copper pour with ≥4 thermal vias - achieving junction-to-ambient resistance near 40°C/W in production-grade layouts.