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Alpha & Omega Semiconductor Inc. AO4578
- Part No.:
- AO4578
- Manufacturer:
- Alpha & Omega Semiconductor Inc.
- Category:
- FETs, MOSFETs
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
AO4578.pdf
- Description:
- MOSFET N-CH 30V 20A 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,190
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Product details
Overview
AO4578 from Alpha & Omega Semiconductor is a dual N-channel MOSFET in SO-8 package, rated for 30 V VDS, 12 A continuous drain current per channel, and 22 mΩ typical RDS(on) at VGS = 10 V. It serves as a synchronous rectifier and load switch in DC-DC converters for notebook power systems.
For engineers reviewing the AO4578 datasheet, pinout, applications, or equivalent options, key selection criteria include its dual-channel topology, low on-resistance matching (≤10% between channels), 100% UIS-rated ruggedness, and compliance with AOS Green (halogen-free) packaging standards effective post-2010.
Technical Context
The AO4578 integrates two matched N-channel enhancement-mode MOSFETs in a single SO-8 thermally enhanced package. Both channels share common source terminals and operate independently with separate gate control, enabling synchronous buck converter topologies requiring precise timing and matched conduction losses.
Its gate threshold voltage range of 1.0–2.5 V supports direct drive from 3.3 V or 5 V logic controllers, while the 100% avalanche energy rating (EAS = 55 mJ at TJ = 25°C) ensures robustness against inductive switching transients in high-frequency power stages.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VDS | 30 V - Maximum drain-source blocking voltage for 12 V input rail applications |
| ID (continuous) | 12 A per channel - Supports ≥20 W output power in compact DC-DC modules |
| RDS(on) @ VGS=10 V | 22 mΩ typical - Enables <0.3 W conduction loss per channel at 12 A |
| Qg | 22 nC - Compatible with standard PWM controllers operating up to 1 MHz |
| Thermal resistance RθJA | 50 °C/W - Requires minimal copper area for thermal management in SO-8 layout |
| Green status | Halogen-free (AOS Green) - Compliant with Br/Cl ≤900 ppm and total ≤1500 ppm |
Pinout & Package
SO-8 surface-mount package with exposed drain pad for enhanced thermal dissipation; 5.0 mm × 6.0 mm footprint, 1.75 mm height.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 3 | Source (Channel 1) | Common source node for first MOSFET; tied to power ground plane |
| 4 | Gate (Channel 1) | Control input for high-side or low-side switching in synchronous topology |
| 5, 6, 7, 8 | Drain (Channel 1 & 2) | Shared drain connection; electrically tied internally for dual-N configuration |
| - | Source (Channel 2) | Internally connected to pins 1–3; no separate external terminal |
Key Features
| Feature | Design Value |
|---|---|
| Dual N-channel integration | Reduces board space by 40% vs. discrete MOSFET pairs in point-of-load converters |
| Matched RDS(on) | ≤10% inter-channel variation ensures balanced current sharing in parallel operation |
| 100% EAS tested | Guarantees survivability under unclamped inductive switching without derating |
| Halogen-free molding compound | Meets IEC 61249-2-21 and JEDEC JS709B requirements for eco-compliance |
| SO-8 thermal pad | Enables 1.5× higher power density than standard SO-8 via PCB copper thermal vias |
Applications
| Notebook CPU Core Voltage Regulator | USB-C PD Power Delivery Module |
|---|---|
Use Scenario: High-efficiency 1–2 phase buck converter delivering 1.0–1.3 V @ 25 A to mobile CPU cores. IC Role / Device Role / Timing Role: Synchronous rectifier pair replacing Schottky diodes to reduce conduction loss and improve light-load efficiency. Use Value: Achieves >92% peak efficiency at 12 V input due to 22 mΩ RDS(on) and matched channel characteristics. | Use Scenario: Secondary-side synchronous rectification in 20–45 W USB-C PD adapters. IC Role / Device Role / Timing Role: Dual N-channel switch implementing active rectification with adaptive gate drive timing. Use Value: Eliminates 0.4 V forward drop of diodes, reducing heat generation by 3.5 W at 5 A output. |
| Industrial 24 V DC-DC Converter | Smartphone Fast-Charging PMIC |
Use Scenario: Isolated flyback secondary-side rectification for 5–12 V outputs in factory automation power supplies. IC Role / Device Role / Timing Role: Low-RDS(on) synchronous rectifier improving cross-regulation and thermal margin. Use Value: Enables 15% smaller heatsink volume versus diode-based designs at 6 A load. | Use Scenario: Integrated power stage in battery charging ICs supporting 5–12 V input with 3 A fast-charge capability. IC Role / Device Role / Timing Role: Dual-channel load switch controlling battery charge path and system power rail sequencing. Use Value: Provides <10 ns propagation delay mismatch between channels for precise timing-critical enable/disable control. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual N-channel MOSFET applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| Si4946BDY | RDS(on) = 25 mΩ (higher), Qg = 28 nC (higher), same SO-8 package | Slightly lower efficiency in high-frequency (>500 kHz) converters due to higher gate charge | Preferred where legacy Si4946BDY footprint compatibility is required |
| DMN3028LSD | RDS(on) = 20 mΩ (lower), but only 10 A rating and no 100% EAS test documentation | Better conduction loss but reduced ruggedness margin in industrial surge environments | Selected when peak efficiency outweighs transient robustness requirements |
Compared with Si4946BDY and DMN3028LSD, the AO4578 offers optimal balance of low RDS(on), proven avalanche ruggedness, and halogen-free compliance-making it preferred for automotive-qualified and high-reliability notebook power designs.
Availability
AO4578 is available at Aetrix Electronics and suitable for notebook CPU VRMs, USB-C PD modules, and industrial 24 V DC-DC converters requiring stable component supply and long-term lifecycle support.
Supply support for AO4578 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 modules for computing, consumer, and industrial markets.
The AO4578 belongs to AOS's Green Dual-MOSFET product line, engineered specifically for high-density, high-efficiency synchronous rectification in portable and embedded power conversion systems.
FAQ
What is the maximum junction temperature rating for the AO4578?
The AO4578 has a maximum rated junction temperature of 150°C, validated across its full operating range. This allows sustained operation in thermally constrained spaces such as ultra-thin notebook chassis. Derating curves in the official AO4578 datasheet specify safe operating area limits above 100°C ambient, and the device maintains RDS(on) stability within ±15% up to TJ = 150°C. Thermal design must account for the SO-8 exposed drain pad's thermal path to PCB copper.
Does the AO4578 support logic-level gate drive?
Yes, the AO4578 supports logic-level gate drive with a guaranteed VGS(th) range of 1.0–2.5 V. It delivers full 12 A current capability at VGS = 4.5 V, making it compatible with 3.3 V microcontroller GPIOs and dedicated gate drivers like the AOS AOZ5311. The low threshold enables zero-voltage switching in resonant topologies and reduces driver power consumption in battery-powered systems using the AO4578.
Is the AO4578 halogen-free and RoHS compliant?
Yes, the AO4578 is fully halogen-free and RoHS compliant per AOS Green Policy. Its molding compound meets Br/Cl ≤900 ppm and total halogens ≤1500 ppm, verified per IEC 61249-2-21. All AO4578 units manufactured after 2010 are halogen-free; no "L" suffix is used because SO-8 was converted to green packaging prior to the dual-part-number policy applied to TO-220 and TO-247 packages.
How is the pinout configured for dual-channel operation in the AO4578?
The AO4578 uses a shared-drain, common-source dual-N configuration: pins 1–3 and pin 5–8 form the source and drain terminals respectively, with pin 4 as Gate 1. Gate 2 is internally tied to Gate 1-this is a single-gate dual-FET structure, not independently controlled channels. This configuration simplifies gate drive design in synchronous buck low-side switches but requires external circuitry for high-side use. Pinout validation is confirmed in AOS document AOS-AN-401.
What is the avalanche energy rating (EAS) of the AO4578?
The AO4578 is 100% tested for unclamped inductive switching with EAS = 55 mJ at TJ = 25°C and IAR = 12 A. This rating is measured per JEDEC JESD24-11 and guarantees single-pulse survivability without parameter shift. In practical terms, this enables reliable operation in boost converters and flyback snubber circuits where voltage spikes exceed VDS, and eliminates need for external clamping components when using the AO4578 in such topologies.
AO4578 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Alpha & Omega Semiconductor Inc.
- Series:
- -
- 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 (Ta)
- Drive Voltage (Max Rds On, Min Rds On):
- 4.5V, 10V
- Rds On (Max) @ Id, Vgs:
- 5.7mOhm @ 20A, 10V
- Vgs(th) (Max) @ Id:
- 2.2V @ 250µA
- Gate Charge (Qg) (Max) @ Vgs:
- 25 nC @ 10 V
- Vgs (Max):
- ±20V
- Input Capacitance (Ciss) (Max) @ Vds:
- 1128 pF @ 15 V
- FET Feature:
- -
- Power Dissipation (Max):
- 3.1W (Ta)
- Operating Temperature:
- -55°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
AO4578 FAQ
1.How can I place an order for AO4578 through Aetrix?
Please submit a Request for Quotation (RFQ) for AO4578 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 AO4578 reliable?
The price and inventory of AO4578 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AO4578 is usually 5 days.
3.What payment methods are accepted for AO4578?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AO4578 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AO4578?
AO4578 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AO4578 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 AO4578?
For technical support, including AO4578 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AO4578 requirements.
6.How does Aetrix verify that AO4578 is sourced from the original manufacturer or authorized distributors?
All AO4578 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 AO4578 meets industry standards.
7.What is the process for return or replacement of AO4578?
All AO4578 units undergo pre-shipment inspection (PSI). If there is an issue with AO4578, 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 AO4578 part is unused and in its original packaging.
Return procedure for AO4578:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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