Alpha & Omega Semiconductor Inc. AOC2421

Overview

AOC2421 from Alpha & Omega Semiconductor is a P-channel enhancement-mode MOSFET using advanced trench technology, rated for -8V drain-source voltage, -2.5A continuous drain current at V_GS = -2.5V, and R_DS(ON) < 60 mΩ under same conditions; it operates down to V_GS = -1.2V and supports low-voltage logic-level gate drive in compact load-switch applications.

For engineers reviewing the AOC2421 datasheet, pinout, applications, or equivalent options, key selection considerations include its 1.2V logic-compatible gate threshold, HBM Class 2 ESD rating, AlphaDFN 0.97×0.97 mm package with exposed drain pad, and verified performance in battery protection and USB port power control circuits.

Technical Context

The AOC2421 employs trench-gate vertical structure to achieve low R_DS(ON) and reduced gate charge (Q_g = 7.5–13 nC), enabling fast switching with t_D(on) = 285 ns and t_D(off) = 1870 ns under resistive load conditions. Its V_GS(th) range of -0.2 to -0.7 V ensures reliable turn-on at low gate voltages while maintaining ±5 V maximum gate-source rating.

Thermal design is supported by R_θJA = 110 °C/W (min pad) and 160 °C/W (steady-state), with junction temperature range from -55 °C to +150 °C. The body diode exhibits V_SD = -0.6 to -1.0 V and fast reverse recovery (t_rr = 12 ns, Q_rr = 4 nC) under IF = -1.5 A, dI/dt = 100 A/μs conditions.

Key Specifications

Pinout & Package

Package: AlphaDFN 0.97×0.97 mm, 4-lead, bottom-exposed drain pad (thermal enhancement). Pin 1 = Gate (G), Pin 2 = Source (S), Pin 3 = Drain (D), Pin 4 = Source (S) - dual-source configuration improves current handling and thermal path.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AOSD20211 and DMN2021LFG-7, the AOC2421 uniquely balances 1.2 V gate compatibility, Class 2 ESD, and 0.97 mm × 0.97 mm footprint-making it optimal for miniaturized, low-voltage battery-powered systems where gate drive headroom and board area are critical.

Availability

AOC2421 is available at Aetrix Electronics and suitable for battery protection circuits, USB Type-C power switches, and IoT sensor node power gating requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.

Supply support for AOC2421 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-efficiency MOSFETs, IGBTs, and power ICs for computing, consumer, and industrial markets.

The AOC2421 belongs to AOS's AlphaDFN logic-level P-channel MOSFET product line, engineered specifically for space-constrained, low-voltage power management in portable and wearable electronics.

FAQ

What is the maximum continuous drain current rating for the AOC2421?

The AOC2421 is rated for -2.5 A continuous drain current (I_D) at T_A = 25 °C with V_GS = -2.5 V, mounted on a PCB with minimum copper pad. Derating applies above 25 °C ambient per the R_θJA = 110 °C/W thermal resistance specification. At 70 °C ambient, the usable I_D drops to approximately -1.8 A for safe operation within T_J ≤ 150 °C.

Does the AOC2421 support gate drive voltages lower than -2.5 V?

Yes, the AOC2421 is specifically designed for low-voltage logic compatibility and fully enhances at V_GS = -1.2 V, with guaranteed R_DS(ON) < 115 mΩ at that condition. Its V_GS(th) range of -0.2 V to -0.7 V ensures predictable turn-on behavior even with weak or partially discharged gate drive sources, making it suitable for direct interface with 1.2 V, 1.8 V, and 2.5 V microcontroller GPIOs.

What is the thermal resistance (R_θJA) of the AOC2421 and how does it affect PCB layout?

The AOC2421 has R_θJA = 110 °C/W with minimum pad PCB layout and 160 °C/W under steady-state conditions. This means effective thermal management requires connecting the exposed drain pad to ≥ 25 mm² of internal or external copper pour. Reducing thermal resistance by 30% (to ~77 °C/W) is achievable with two internal copper layers and thermal vias-critical for sustaining 2.5 A continuous current without exceeding T_J = 150 °C.

Is the AOC2421 pin-compatible with other AlphaDFN 0.97×0.97 mm P-channel MOSFETs?

The AOC2421 uses the standardized AlphaDFN 0.97×0.97 mm 4-lead package with pin 1 = Gate, pins 2 & 4 = Source, pin 3 = Drain. It shares identical footprint and solder mask layout with AOS parts such as AOC2401 and DMN2021LFG-7, enabling direct PCB replacement where electrical specs align. However, gate threshold and R_DS(ON) differ across variants, so functional validation is required before substitution.

What is the body diode forward voltage (V_SD) of the AOC2421 and how does it impact reverse-current paths?

The AOC2421 body diode exhibits V_SD = -0.6 V to -1.0 V at I_S = -1 A and T_J = 25 °C. This low forward voltage minimizes conduction loss during freewheeling or reverse-battery protection, while its fast t_rr = 12 ns and low Q_rr = 4 nC reduce switching losses and voltage spikes in inductive load switching. In bidirectional current paths, this diode behavior must be accounted for in layout and timing analysis.