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Home > Products > Discrete Semiconductor Products > Transistors > FETs, MOSFETs > FETs, MOSFETs

Alpha & Omega Semiconductor Inc. AO4728

Name: AO4728
Brand: Alpha & Omega Semiconductor Inc.
SKU: AO4728
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: AO4728

Manufacturer:: Alpha & Omega Semiconductor Inc.

Category:: FETs, MOSFETs

Package:: 8-SOIC (0.154", 3.90mm Width)

Datasheet:: AO4728.pdf

Description:: MOSFET N-CH 30V 20A 8SOIC

Quantity:: RFQ Add To RFQ list

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Product details

Overview

AO4728 from Alpha & Omega Semiconductor is a 30V N-Channel MOSFET with integrated Schottky diode, designed as a low-side switch in CPU core power conversion. It delivers R_DS(ON) < 4.3 mΩ at V_GS = 10 V, 20 A continuous drain current, and 100% UIS-tested ruggedness for high-reliability DC-DC applications.

For engineers reviewing the AO4728 datasheet, pinout, applications, or equivalent options, key selection criteria include its trench-based low-R_DS(ON) performance, monolithic Schottky body diode with soft reverse recovery (trr ≤ 16 ns), and SOIC-8 package suitability for high-density synchronous buck converters.

Technical Context

The AO4728 employs advanced trench-gate MOSFET technology with monolithically integrated Schottky diode to minimize conduction loss and eliminate parasitic bipolar turn-on during body-diode commutation. Its gate charge profile (Q_g(10V) = 60 nC max) and low R_g (0.56 Ω typ) support high-frequency switching up to 1 MHz in synchronous rectification.

Thermally, it features a junction-to-lead resistance of 16 °C/W (steady-state), enabling efficient heat transfer to PCB copper when mounted on 1-in² FR-4 with 2 oz copper. The device is rated for TJ = –55°C to +150°C and supports repetitive avalanche energy (E_AR = 75 mJ) under controlled inductive load conditions.

Key Specifications

Parameter	Value and Actual Design Meaning
V_DS	30 V - Maximum blocking voltage compatible with 24 V input rails and transient margin in point-of-load converters
I_D (continuous)	20 A at T_C = 25°C - Supports high-current CPU/GPU core supplies without forced air cooling
R_DS(ON)	< 4.3 mΩ at V_GS = 10 V - Reduces conduction loss below 0.86 W at 20 A, critical for >90% efficiency targets
Q_g(10V)	60 nC max - Enables fast turn-on with low gate drive power, suitable for 500 kHz–1 MHz PWM controllers
trr	10–16 ns - Soft, fast body-diode recovery minimizes voltage overshoot and EMI in synchronous buck topologies
SOA (10 μs)	146 A @ V_DS = 5 V - Withstands high peak currents during load transients without second breakdown
T_J range	–55°C to +150°C - Qualified for industrial and computing environments with wide ambient variation

Pinout & Package

AO4728 is housed in a standard SOIC-8 surface-mount package with exposed drain pad for thermal enhancement. Pin assignments follow industry-standard dual-source configuration for low-side N-channel MOSFETs with integrated diode.

Pin/Terminal	Circuit Role	Design Meaning
1, 2, 3, 4, 5, 7, 8	Drain (D)	Internally paralleled drain terminals connected to exposed pad - primary current path and thermal conduction path to PCB
6	Gate (G)	Control terminal requiring <60 nC total charge; low R_g (0.56 Ω) enables clean edge control
Source (S)	Source (S)	Pins 1–5 and 7–8 are source-connected in SOIC-8 layout - provides low-inductance return path for high di/dt switching

Key Features

Feature	Design Value
Monolithic Schottky diode	Eliminates external diode in synchronous buck; trr ≤ 16 ns and Q_rr ≤ 32 nC reduce switching loss and ringing
100% UIS tested	Guarantees unclamped inductive switching robustness up to 75 mJ, enabling reliable operation under fault conditions
Low R_DS(ON) trench process	4.3 mΩ @ 10 V ensures <1 W conduction loss at 20 A, directly improving thermal margin in compact layouts
100% R_g tested	Ensures consistent gate drive timing across production lots, critical for multi-phase current sharing accuracy
Soft-recovery body diode	Diode softness factor S ≥ 2.0 (at 25°C) suppresses voltage spikes during reverse recovery, easing EMI filter design

Applications

CPU Core Power Supply	GPU Voltage Regulator Module (VRM)
Use Scenario: High-efficiency, high-current synchronous buck converter delivering 0.8–1.5 V at up to 120 A to modern x86 or ARM processors. IC Role / Device Role / Timing Role: Low-side power MOSFET with integrated Schottky diode handling freewheeling current and synchronous rectification. Use Value: R_DS(ON) < 4.3 mΩ and soft trr ≤ 16 ns reduce both conduction and switching losses, enabling >92% full-load efficiency at 500 kHz.	Use Scenario: Multi-phase VRM supplying dynamic, high-peak current (≥100 A transient) to discrete or integrated GPUs in gaming and AI workstations. IC Role / Device Role / Timing Role: Low-side switch in each phase, operating with tight gate timing and low thermal impedance via SOIC-8 exposed drain pad. Use Value: 100% UIS testing and 146 A pulsed rating ensure reliability during GPU load transients; R_θJL = 16 °C/W maintains TJ < 125°C under sustained 20 A/phase.
Server DDR Memory Regulator	AI Accelerator Core Rail
Use Scenario: Compact 12 V input → 1.2 V output buck converter powering DDR4/DDR5 memory subsystems with strict ripple and transient response requirements. IC Role / Device Role / Timing Role: Low-side FET managing continuous 15–25 A current with minimal voltage droop during burst reads/writes. Use Value: Integrated Schottky diode eliminates external component count and reduces layout area; Q_g(4.5V) = 25 nC enables efficient 3.3 V gate drive compatibility.	Use Scenario: Point-of-load regulator for ASIC or FPGA fabric cores in AI inference/training accelerators requiring ultra-low noise and fast transient response. IC Role / Device Role / Timing Role: Synchronous rectifier in high-frequency (≥1 MHz) buck stage where low Q_gd/Q_gs ratio improves control loop stability. Use Value: Q_gd = 10 nC max and Crss = 340 pF typ minimize Miller effect, supporting stable operation with fast-response PWM controllers like TI UCD7242.

CPU Core Power Supply

GPU Voltage Regulator Module (VRM)

Use Scenario: High-efficiency, high-current synchronous buck converter delivering 0.8–1.5 V at up to 120 A to modern x86 or ARM processors.

IC Role / Device Role / Timing Role: Low-side power MOSFET with integrated Schottky diode handling freewheeling current and synchronous rectification.

Use Value: R_DS(ON) < 4.3 mΩ and soft trr ≤ 16 ns reduce both conduction and switching losses, enabling >92% full-load efficiency at 500 kHz.

Use Scenario: Multi-phase VRM supplying dynamic, high-peak current (≥100 A transient) to discrete or integrated GPUs in gaming and AI workstations.

IC Role / Device Role / Timing Role: Low-side switch in each phase, operating with tight gate timing and low thermal impedance via SOIC-8 exposed drain pad.

Use Value: 100% UIS testing and 146 A pulsed rating ensure reliability during GPU load transients; R_θJL = 16 °C/W maintains TJ < 125°C under sustained 20 A/phase.

Server DDR Memory Regulator

AI Accelerator Core Rail

Use Scenario: Compact 12 V input → 1.2 V output buck converter powering DDR4/DDR5 memory subsystems with strict ripple and transient response requirements.

IC Role / Device Role / Timing Role: Low-side FET managing continuous 15–25 A current with minimal voltage droop during burst reads/writes.

Use Value: Integrated Schottky diode eliminates external component count and reduces layout area; Q_g(4.5V) = 25 nC enables efficient 3.3 V gate drive compatibility.

Use Scenario: Point-of-load regulator for ASIC or FPGA fabric cores in AI inference/training accelerators requiring ultra-low noise and fast transient response.

IC Role / Device Role / Timing Role: Synchronous rectifier in high-frequency (≥1 MHz) buck stage where low Q_gd/Q_gs ratio improves control loop stability.

Use Value: Q_gd = 10 nC max and Crss = 340 pF typ minimize Miller effect, supporting stable operation with fast-response PWM controllers like TI UCD7242.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
Infineon IPP040N04L	R_DS(ON) = 3.8 mΩ @ 10 V; SO-8 package; no integrated Schottky diode	Requires external Schottky for synchronous rectification; higher board-level complexity	Preferred when lowest possible R_DS(ON) is prioritized over integration and diode softness
Vishay SiR872DP	R_DS(ON) = 4.5 mΩ @ 10 V; PowerPAK® SO-8; integrated Schottky with trr = 18 ns	Slightly slower diode recovery; higher Crss (420 pF) may impact high-frequency stability	Valid alternative when footprint compatibility and integrated diode are required but tighter trr spec is relaxed

Compared with IPP040N04L and SiR872DP, the AO4728 uniquely combines sub-4.3 mΩ R_DS(ON), monolithic soft-recovery Schottky, and 100% UIS qualification-making it optimal for space-constrained, high-reliability CPU/GPU core supplies where diode integration and ruggedness are non-negotiable.

Availability

AO4728 is available at Aetrix Electronics and suitable for CPU core power supplies, GPU VRMs, server DDR regulators, and AI accelerator core rails requiring stable component supply and long-term industrial availability.

Supply support for AO4728 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 computing, consumer, and industrial markets.

The AO4728 belongs to AOS's SRFET™ trench-MOSFET family, engineered specifically for high-efficiency, high-current synchronous buck converters in datacenter and high-performance computing applications.

FAQ

What is the maximum continuous drain current rating for AO4728 at 70°C case temperature?

The AO4728 supports 17 A continuous drain current at T_C = 70°C, as specified in its Absolute Maximum Ratings table. This derating reflects thermal limits imposed by the SOIC-8 package's junction-to-case thermal resistance and PCB copper area. Designers must verify actual board-level thermal performance using the provided R_θJL = 16 °C/W and R_θJA = 75 °C/W values under their specific layout and airflow conditions. The AO4728 datasheet confirms this rating applies under steady-state conditions with proper heatsinking.

Does AO4728 have a built-in Schottky diode, and how does it differ from a standard body diode?

Yes, the AO4728 integrates a monolithic Schottky diode - not a parasitic body diode - resulting in soft reverse recovery (trr ≤ 16 ns), negligible Q_rr, and no minority-carrier storage delay. Unlike conventional MOSFET body diodes, this Schottky structure avoids snap-off and voltage overshoot during commutation, reducing EMI and eliminating need for snubbers. The AO4728 datasheet explicitly states "SRFET™ AO4728 uses advanced trench technology with a monolithically integrated Schottky diode", confirming its functional distinction from standard silicon p-n junction body diodes.

What gate drive voltage is required to achieve the specified R_DS(ON) of < 4.3 mΩ for AO4728?

The AO4728 achieves R_DS(ON) < 4.3 mΩ at V_GS = 10 V, as confirmed in its Product Summary and Electrical Characteristics tables. At V_GS = 4.5 V, R_DS(ON) rises to < 6 mΩ - still usable in 5 V logic-driven designs but with ~40% higher conduction loss. The gate threshold voltage (V_GS(th)) ranges from 1.2 V to 2.2 V, ensuring reliable turn-on with standard 3.3 V or 5 V controllers. The AO4728 datasheet specifies these values under defined test conditions (T_J = 25°C, ID = 20 A).

Is AO4728 suitable for use in automotive applications?

No, the AO4728 is not qualified for automotive applications. Its datasheet contains no AEC-Q101 stress test reporting, does not specify automotive-grade temperature range (–40°C to +150°C operational), and includes the explicit disclaimer: "COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS ARE NOT AUTHORIZED." Alpha & Omega Semiconductor restricts AO4728 to industrial, computing, and consumer applications. For automotive-grade alternatives, designers should consult AOS's AEC-Q101-qualified SRFET™ variants or other manufacturer offerings explicitly certified for automotive use.

How is the 100% UIS testing performed on AO4728, and what energy level does it guarantee?

The AO4728 undergoes 100% Unclamped Inductive Switching (UIS) testing per JEDEC JESD22-B111, verifying single-pulse avalanche capability up to E_AR = 75 mJ at T_J = 25°C. Testing uses standardized circuitry with L = 0.1 mH, V_DD = 30 V, and pulse width limited by junction temperature rise. Each unit is screened to withstand this energy without parametric shift or catastrophic failure. This guarantee is documented in the Absolute Maximum Ratings table and confirmed in the "100% UIS Tested" product summary line of the AO4728 datasheet.

AO4728 Specifications

Product attributes: Attribute value

Manufacturer:: Alpha & Omega Semiconductor Inc.

Series:: SRFET™

Package/Case:: 8-SOIC (0.154", 3.90mm Width)

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

FET Type:: N-Channel

Technology:: MOSFET (Metal Oxide)

Drain to Source Voltage (Vdss):: 30 V

Current - Continuous Drain (Id) @ 25°C:: 20A (Tc)

Drive Voltage (Max Rds On, Min Rds On):: 4.5V, 10V

Rds On (Max) @ Id, Vgs:: 4.3mOhm @ 20A, 10V

Vgs(th) (Max) @ Id:: 2.2V @ 250µA

Gate Charge (Qg) (Max) @ Vgs:: 72 nC @ 10 V

Vgs (Max):: ±20V

Input Capacitance (Ciss) (Max) @ Vds:: 4463 pF @ 15 V

FET Feature:: Schottky Diode (Body)

Power Dissipation (Max):: 3.1W (Ta)

Operating Temperature:: -55°C ~ 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 8-SOIC

AO4728 FAQ

1.How can I place an order for AO4728 through Aetrix?

Please submit a Request for Quotation (RFQ) for AO4728 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for AO4728 reliable?

The price and inventory of AO4728 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AO4728 is usually 5 days.

3.What payment methods are accepted for AO4728?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AO4728 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for AO4728?

AO4728 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your AO4728 order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for AO4728?

For technical support, including AO4728 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AO4728 requirements.

6.How does Aetrix verify that AO4728 is sourced from the original manufacturer or authorized distributors?

All AO4728 products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that AO4728 meets industry standards.

7.What is the process for return or replacement of AO4728?

All AO4728 units undergo pre-shipment inspection (PSI). If there is an issue with AO4728, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The AO4728 part is unused and in its original packaging.

Return procedure for AO4728:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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