Alpha & Omega Semiconductor Inc. AOTF256L

Overview

AOTF256L from Alpha & Omega Semiconductor is a 150V N-Channel trench MOSFET optimized for high-frequency switching in power conversion stages, featuring R_DS(ON) < 85 mΩ at V_GS = 10 V, 12 A continuous drain current, and 100% UIS-tested ruggedness. It serves as a primary switch or synchronous rectifier in boost converters and LED backlighting systems.

For engineers reviewing the AOTF256L datasheet, pinout, applications, or equivalent options, key selection criteria include its low gate charge (Q_g = 15.5–22 nC), ultra-low C_iss (1165 pF) and C_oss (61.5 pF), thermal resistance R_θJC = 4.6 °C/W, and TO-220F package suitability for heatsink-mounted industrial power supplies.

Technical Context

The AOTF256L employs trench-gate MOSFET architecture to simultaneously minimize conduction loss (via sub-85 mΩ R_DS(ON)) and switching loss (via low C_iss/C_oss and fast t_r = 5 ns, t_f = 2.5 ns). Its 100% unclamped inductive switching (UIS) and gate resistance (R_g = 1.1–3.3 Ω) testing ensure reliability under transient overcurrent conditions.

Designed for operation up to T_J = 175 °C, the device delivers stable performance across consumer, telecom, and industrial power supplies - with body-diode recovery Q_rr = 265 nC and t_rr = 37 ns supporting efficient synchronous rectification in DC-DC topologies.

Key Specifications

Pinout & Package

Package: TO-220F (full-pack, insulated tab, vertical mounting). Thermally enhanced plastic package with isolated drain tab rated for 1500 V isolation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with STP14NK150Z and IRF640NPBF, the AOTF256L provides superior high-frequency efficiency due to its trench architecture, certified UIS robustness, and lower R_DS(ON) × Q_g FOM - making it the preferred choice for compact, thermally constrained, and high-reliability power conversion.

Availability

AOTF256L is available at Aetrix Electronics and suitable for boost converters, synchronous rectifiers, and industrial AC-DC adapters requiring stable component supply, consistent parametric performance, and long-term manufacturing continuity.

Supply support for AOTF256L 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 AOTF256L belongs to AOS's TrenchFET® Gen V family, engineered specifically for high-efficiency, high-frequency DC-DC and AC-DC power supplies in consumer, telecom, and industrial markets.

FAQ

What is the maximum continuous drain current rating for the AOTF256L at 100°C case temperature?

The AOTF256L supports 35 A pulsed drain current and 8.5 A continuous drain current at T_C = 100 °C, per its Absolute Maximum Ratings table. This value reflects package-limited current handling under sustained thermal conditions and assumes proper heatsinking with R_θJC = 4.6 °C/W. The AOTF256L must not exceed this limit to maintain junction temperature below 175 °C.

Does the AOTF256L have a fully isolated drain tab, and what is its isolation voltage rating?

Yes, the AOTF256L uses a TO-220F package with a fully insulated drain tab rated for 1500 V isolation between drain and mounting surface. This allows direct attachment to grounded heatsinks without additional insulation hardware, simplifying thermal design in high-voltage applications such as 48 V telecom supplies and industrial PFC stages.

Is the AOTF256L suitable for use as a synchronous rectifier, and what body-diode parameters support that function?

Yes, the AOTF256L is qualified for synchronous rectification. Its body diode exhibits V_SD = 0.72–1.0 V at I_S = 1 A, t_rr = 37 ns, and Q_rr = 265 nC - all measured under standardized conditions (I_F = 10 A, dI/dt = 500 A/ms). These values enable low-loss commutation in secondary-side LLC and buck converters when properly gate-driven.

What gate-drive voltage range is specified for reliable operation of the AOTF256L?

The AOTF256L specifies a gate-source voltage range of ±20 V maximum, with gate threshold voltage V_GS(th) = 1.8–2.8 V at I_D = 250 µA. For full enhancement and minimal R_DS(ON), a V_GS of 10 V is recommended; operation at 4.5 V yields R_DS(ON) < 100 mΩ, supporting 3.3 V logic-compatible drive in space-constrained designs.

How is the thermal performance of the AOTF256L characterized, and what does R_θJC = 4.6 °C/W mean in practice?

R_θJC = 4.6 °C/W means that for every watt dissipated at the die, the junction-to-case temperature rise is 4.6 °C under ideal heatsink contact. In practice, with 35 W power dissipation at T_C = 100 °C, the AOTF256L achieves T_J = 100 + (35 × 4.6) = 261 °C - exceeding its 175 °C limit. Therefore, actual usable power is capped at ~15.2 W at T_C = 100 °C, confirming the need for appropriate derating per Figure 13 in the AOTF256L datasheet.