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

Vishay Siliconix SI4778DY-T1-E3

Name: SI4778DY-T1-E3
Brand: Vishay Siliconix
SKU: SI4778DY-T1-E3
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: SI4778DY-T1-E3

Manufacturer:: Vishay Siliconix

Category:: FETs, MOSFETs

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

Datasheet:: SI4778DY-T1-E3.pdf

Description:: MOSFET N-CH 25V 8A 8SO

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Product details

Overview

SI4778DY-T1-E3 from Vishay Siliconix is an N-channel 25-V TrenchFET® Power MOSFET in SO-8 package, with R_DS(on) = 0.023 Ω at V_GS = 10 V, 8 A continuous drain current (package-limited), and 5.5 nC total gate charge. It serves as a high-efficiency synchronous rectifier or main switch in notebook system power rails and DC/DC converters.

For engineers reviewing the SI4778DY-T1-E3 datasheet, SI4778DY-T1-E3 pinout, SI4778DY-T1-E3 application, or SI4778DY-T1-E3 equivalent, key selection criteria include its low R_DS(on) at 4.5 V drive, 100% UIS-tested ruggedness, halogen-free construction, and SO-8 thermal performance under 1" × 1" FR4 mounting.

Technical Context

This MOSFET employs trench-gate silicon technology optimized for low conduction loss and fast switching in high-frequency synchronous buck converters. Its gate threshold voltage (1.0–2.2 V) enables reliable turn-on with standard 3.3 V or 5 V logic-level drivers, while its 16 V maximum gate-source rating supports robust gate drive margin.

The device features a fully characterized body diode with t_rr = 15–30 ns and Q_rr = 8–16 nC, enabling efficient reverse recovery in hard-switched topologies. Thermal resistance from junction-to-foot is 19 °C/W (typical), supporting direct thermal coupling to PCB copper in compact notebook power stages.

Key Specifications

Parameter	Value and Actual Design Meaning
V_DS	25 V - Maximum blocking voltage suitable for 12 V input DC/DC stages with margin.
R_DS(on)	0.023 Ω @ V_GS = 10 V - Enables ≤1.3 W conduction loss at 7 A, critical for thermally constrained notebook PCBs.
I_D (cont)	8 A (package-limited) - Sustains full load in 1–2 phase VRMs without derating at TC = 25 °C.
Q_g	5.5 nC @ V_GS = 4.5 V - Minimizes gate drive power and enables efficient operation with low-voltage controllers.
R_thJA	42 °C/W (typ) - Predictable junction temperature rise on standard FR4, supporting thermal design without heatsinks.
V_GS(th)	1.0–2.2 V - Ensures clean turn-on with 3.3 V GPIO or PWM controller outputs.
t_rr	15–30 ns - Reduces body diode switching loss and EMI in synchronous rectification mode.

Pinout & Package

SO-8 (MS-012) surface-mount package with exposed drain paddle for enhanced thermal dissipation. Pin 1–8 arranged in dual-row narrow-body layout per JEDEC MS-012 standard.

Pin/Terminal	Circuit Role	Design Meaning
1, 2, 3, 4, 5, 8	Drain (D)	Internally connected to exposed paddle; primary current path and thermal interface to PCB copper.
6	Gate (G)	Control terminal; low input capacitance (C_iss = 680 pF) reduces driver loading.
7	Source (S)	Reference node for gate drive; tied to power ground plane in synchronous buck high-side configuration.

Key Features

Feature	Design Value
TrenchFET® architecture	Delivers lowest R_DS(on) per die area among Vishay's 25 V SO-8 MOSFETs, enabling smaller footprint in multi-phase VRMs.
100% UIS tested	Guarantees avalanche energy handling (E_AS = 1.25 mJ) without screening failure, critical for transient overload survival.
Halogen-free construction	Meets IEC 61249-2-21, supporting RoHS-compliant and environmentally regulated notebook designs.
Low Q_gd/Q_g ratio	Q_gd = 1.5 nC / Q_g = 5.5 nC → ~27% - Improves switching speed control and reduces Miller-induced shoot-through risk.

Applications

Notebook System Power	DC/DC Converter
Use Scenario: Primary high-side switch in 1–2 phase CPU/GPU VRMs on ultrabook motherboards. IC Role / Device Role / Timing Role: Main power switch synchronized to controller PWM signal; operates at 300–1000 kHz. Use Value: 0.023 Ω R_DS(on) at 10 V reduces conduction loss by >25% vs. legacy 30 V SO-8 MOSFETs, extending battery runtime.	Use Scenario: Synchronous rectifier in isolated forward or active-clamp forward converters for display backlight supplies. IC Role / Device Role / Timing Role: Low-side synchronous rectifier driven by transformer-coupled gate signal; replaces Schottky diode. Use Value: Body diode V_SD = 0.8–1.2 V and t_rr < 30 ns minimize reverse recovery loss and improve efficiency by 3–5% over discrete diodes.
Gaming Laptop VRM	USB-C PD Power Path
Use Scenario: High-current phase leg in multi-phase VRMs delivering up to 120 A to discrete GPU modules. IC Role / Device Role / Timing Role: Parallel-switched N-channel MOSFET sharing current with identical devices; gate-driven by dedicated phase controller. Use Value: 8 A continuous rating per device and 30 A pulsed capability support peak GPU loads without thermal throttling on 1" × 1" FR4.	Use Scenario: Input protection switch in USB-C PD sink applications requiring 20 V tolerance and low forward drop. IC Role / Device Role / Timing Role: Load switch controlling power delivery path from Type-C port to system rail; enabled via PMIC GPIO. Use Value: V_GS(th) ≤ 2.2 V ensures reliable turn-on from 3.3 V PMIC outputs, while 25 V V_DS accommodates 20 V PD profiles with safety margin.

Notebook System Power

DC/DC Converter

Use Scenario: Primary high-side switch in 1–2 phase CPU/GPU VRMs on ultrabook motherboards.

IC Role / Device Role / Timing Role: Main power switch synchronized to controller PWM signal; operates at 300–1000 kHz.

Use Value: 0.023 Ω R_DS(on) at 10 V reduces conduction loss by >25% vs. legacy 30 V SO-8 MOSFETs, extending battery runtime.

Use Scenario: Synchronous rectifier in isolated forward or active-clamp forward converters for display backlight supplies.

IC Role / Device Role / Timing Role: Low-side synchronous rectifier driven by transformer-coupled gate signal; replaces Schottky diode.

Use Value: Body diode V_SD = 0.8–1.2 V and t_rr < 30 ns minimize reverse recovery loss and improve efficiency by 3–5% over discrete diodes.

Gaming Laptop VRM

USB-C PD Power Path

Use Scenario: High-current phase leg in multi-phase VRMs delivering up to 120 A to discrete GPU modules.

IC Role / Device Role / Timing Role: Parallel-switched N-channel MOSFET sharing current with identical devices; gate-driven by dedicated phase controller.

Use Value: 8 A continuous rating per device and 30 A pulsed capability support peak GPU loads without thermal throttling on 1" × 1" FR4.

Use Scenario: Input protection switch in USB-C PD sink applications requiring 20 V tolerance and low forward drop.

IC Role / Device Role / Timing Role: Load switch controlling power delivery path from Type-C port to system rail; enabled via PMIC GPIO.

Use Value: V_GS(th) ≤ 2.2 V ensures reliable turn-on from 3.3 V PMIC outputs, while 25 V V_DS accommodates 20 V PD profiles with safety margin.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
Infineon BSC014N04LS	R_DS(on) = 1.4 mΩ @ 10 V (lower), but SO-8 package with different pinout (G/S/D arrangement differs); higher Q_g = 22 nC.	Requires PCB layout change due to non-identical pin mapping; better for ultra-low-loss designs where gate drive strength permits.	Select only if redesigning layout and prioritizing sub-mΩ conduction loss over gate drive simplicity.
ON Semiconductor NTMFS4C09NT1G	R_DS(on) = 2.5 mΩ @ 10 V, same SO-8 footprint, but rated for 40 V V_DS; Q_g = 17 nC; not halogen-free.	Higher voltage rating adds margin for transient spikes but increases cost and gate drive demand; lacks halogen-free compliance.	Prefer when system transients exceed 25 V or halogen-free requirement is waived; otherwise SI4778DY-T1-E3 offers better cost/performance balance.

Compared with BSC014N04LS and NTMFS4C09NT1G, SI4778DY-T1-E3 delivers optimal trade-off of low R_DS(on), logic-level gate compatibility, halogen-free compliance, and SO-8 pinout stability-making it ideal for volume notebook and gaming laptop VRM designs where layout reuse and thermal predictability are critical.

Availability

SI4778DY-T1-E3 is available at Aetrix Electronics and suitable for notebook system power, DC/DC converter, and gaming laptop VRM applications requiring stable component supply, consistent SO-8 sourcing, and halogen-free compliance.

Supply support for SI4778DY-T1-E3 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

Vishay Siliconix is a global leader in discrete semiconductors and passive components, specializing in high-reliability power MOSFETs, diodes, and optoelectronics for demanding industrial and computing applications.

The Si4778DY product line targets high-efficiency, space-constrained DC/DC power conversion in portable computing-designed specifically for synchronous buck stages where low R_DS(on), fast switching, and thermal reliability are essential.

FAQ

What is the maximum continuous drain current rating for SI4778DY-T1-E3?

The SI4778DY-T1-E3 has a continuous drain current rating of 8 A at T_C = 25 °C, limited by package thermal capacity-not silicon capability. At T_C = 70 °C, the rating remains 8 A, but at T_A = 25 °C it drops to 8 A (package-limited) and further to 6.4 A at T_A = 70 °C per datasheet Section 1. This reflects SO-8 thermal constraints under standard FR4 mounting conditions.

Is SI4778DY-T1-E3 suitable for 3.3 V gate drive applications?

Yes, SI4778DY-T1-E3 is fully compatible with 3.3 V gate drive: its gate threshold voltage (V_GS(th)) ranges from 1.0 V to 2.2 V, and R_DS(on) is specified at 0.028 Ω with only 4.5 V V_GS. The device achieves low on-resistance and stable switching behavior even with logic-level controllers commonly used in notebook VRMs.

Does SI4778DY-T1-E3 have avalanche capability, and is it tested?

Yes, SI4778DY-T1-E3 is 100% tested for Unclamped Inductive Switching (UIS) per datasheet Feature list and Absolute Maximum Ratings. It guarantees single-pulse avalanche current (I_AS) of 5 A and energy (E_AS) of 1.25 mJ, ensuring robustness against inductive transients in DC/DC converter switching nodes.

What is the thermal resistance from junction to ambient for SI4778DY-T1-E3?

The SI4778DY-T1-E3 has a typical junction-to-ambient thermal resistance (R_thJA) of 42 °C/W and a maximum of 53 °C/W when mounted on a 1" × 1" FR4 board per datasheet Note b. This value assumes standard surface-mount assembly and defines the baseline for thermal design in notebook power stages without added heatsinking.

How does the body diode performance of SI4778DY-T1-E3 impact synchronous rectifier use?

The SI4778DY-T1-E3 body diode exhibits V_SD = 0.8–1.2 V at I_S = 5.6 A and reverse recovery time t_rr = 15–30 ns, enabling efficient synchronous rectification. Its low Q_rr (8–16 nC) and fast recovery reduce switching loss and EMI compared to Schottky alternatives-especially valuable in high-frequency forward converters used in display power supplies.

SI4778DY-T1-E3 Specifications

Product attributes: Attribute value

Manufacturer:: Vishay Siliconix

Series:: TrenchFET®

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):: 25 V

Current - Continuous Drain (Id) @ 25°C:: 8A (Tc)

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

Rds On (Max) @ Id, Vgs:: 23mOhm @ 7A, 10V

Vgs(th) (Max) @ Id:: 2.2V @ 250µA

Gate Charge (Qg) (Max) @ Vgs:: 18 nC @ 10 V

Vgs (Max):: ±16V

Input Capacitance (Ciss) (Max) @ Vds:: 680 pF @ 13 V

FET Feature:: -

Power Dissipation (Max):: 2.4W (Ta), 5W (Tc)

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

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 8-SOIC

SI4778DY-T1-E3 FAQ

1.How can I place an order for SI4778DY-T1-E3 through Aetrix?

Please submit a Request for Quotation (RFQ) for SI4778DY-T1-E3 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 SI4778DY-T1-E3 reliable?

The price and inventory of SI4778DY-T1-E3 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SI4778DY-T1-E3 is usually 5 days.

3.What payment methods are accepted for SI4778DY-T1-E3?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SI4778DY-T1-E3 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for SI4778DY-T1-E3?

SI4778DY-T1-E3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your SI4778DY-T1-E3 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 SI4778DY-T1-E3?

For technical support, including SI4778DY-T1-E3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SI4778DY-T1-E3 requirements.

6.How does Aetrix verify that SI4778DY-T1-E3 is sourced from the original manufacturer or authorized distributors?

All SI4778DY-T1-E3 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 SI4778DY-T1-E3 meets industry standards.

7.What is the process for return or replacement of SI4778DY-T1-E3?

All SI4778DY-T1-E3 units undergo pre-shipment inspection (PSI). If there is an issue with SI4778DY-T1-E3, 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 SI4778DY-T1-E3 part is unused and in its original packaging.

Return procedure for SI4778DY-T1-E3:

1.Submit a request within 90 days.

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

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