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

Vishay Siliconix SI4447DY-T1-E3

Name: SI4447DY-T1-E3
Brand: Vishay Siliconix
SKU: SI4447DY-T1-E3
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: SI4447DY-T1-E3

Manufacturer:: Vishay Siliconix

Category:: FETs, MOSFETs

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

Datasheet:: SI4447DY-T1-E3.pdf

Description:: MOSFET P-CH 40V 3.3A 8SO

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Product details

Overview

SI4447DY-T1-E3 from Vishay Siliconix is a P-channel enhancement-mode MOSFET designed for high-efficiency switching in low-voltage DC-DC conversion and CCFL inverter circuits. It features -40 V V_DS, 0.054 Ω R_DS(on) at V_GS = -10 V, -4.5 A continuous drain current (T_A = 25 °C), 9 nC total gate charge, and SO-8 package with lead-free finish.

For engineers reviewing the SI4447DY-T1-E3 datasheet, SI4447DY-T1-E3 pinout, SI4447DY-T1-E3 application, or SI4447DY-T1-E3 equivalent, key selection criteria include negative gate threshold voltage (-0.8 to -2.2 V), low R_DS(on) at -4.5 V drive, body diode recovery performance (t_rr = 27–45 ns), and thermal resistance (R_thJA = 85 °C/W steady-state).

Technical Context

This device operates as a single P-channel power switch in high-side configuration, using trench-based silicon architecture for reduced conduction loss and improved switching efficiency. Its gate threshold voltage range (-0.8 to -2.2 V) enables reliable turn-on with standard logic-level negative gate drive, while its 100 % UIS-tested ruggedness supports inductive load switching without external snubbers.

The SO-8 package provides dual-source/drain terminals per side for enhanced current handling and thermal spreading. Its dynamic parameters-including C_iss = 805 pF, Q_gd = 3.6 nC, and t_d(off) = 74–110 ns-support stable operation in 100–500 kHz switching applications where gate drive strength and Miller immunity are critical.

Key Specifications

Parameter	Value and Actual Design Meaning
V_DS	-40 V - Maximum blocking voltage for high-side switch in ≤40 V rail systems
R_DS(on)	0.054 Ω @ V_GS = -10 V - Enables <120 mW conduction loss at -4.5 A
I_D (cont)	-4.5 A @ T_A = 25 °C - Supports compact PCB layout without forced air cooling
Q_g	9 nC (typ) - Reduces gate driver power requirement and switching loss at 200 kHz+
V_GS(th)	-0.8 to -2.2 V - Ensures full enhancement with -3.3 V or -5 V logic-compatible gate drive
t_r/t_f	12–18 ns / 38–60 ns - Supports fast transition control in resonant and PWM topologies
R_thJA	85 °C/W (steady-state) - Limits junction rise to ~128 °C at 1.1 W dissipation on FR4

Pinout & Package

SI4447DY-T1-E3 is housed in a standard SO-8 (MS-012) surface-mount package with exposed drain pads on pins 1, 2, 3, and 4 for thermal and current sharing. The package measures 4.9 mm × 3.9 mm × 1.55 mm (D × E × A) and is RoHS-compliant and lead-free.

Pin/Terminal	Circuit Role	Design Meaning
1, 2, 3, 4	Drain (D)	Common high-current output node; internally paralleled for lower R_DS(on) and improved thermal path
5, 6, 7	Source (S)	Return path for load current; pins 5 and 6 share primary source connection; pin 7 is auxiliary
8	Gate (G)	Control input requiring negative voltage relative to source to turn on; low C_iss enables fast edge rates

Key Features

Feature	Design Value
TrenchFET® architecture	Delivers 20 % lower R_DS(on) vs. planar P-channel MOSFETs at same die size and voltage rating
100 % UIS tested	Guarantees unclamped inductive switching capability up to I_AS = 16 A and E_AS = 13 mJ
Low Q_gd/Q_g ratio	0.4 (3.6/9 nC) - Improves Miller immunity and reduces risk of false turn-on in high-dV/dt environments
Body diode t_rr & Q_rr	27–45 ns / 17–26 nC - Enables synchronous rectification or freewheeling with minimal reverse recovery loss

Applications

CCFL Inverter	High-Side Load Switch
Use Scenario: Driving cold cathode fluorescent lamp (CCFL) backlight in LCD panels using resonant half-bridge topology. IC Role / Device Role / Timing Role: High-side P-channel switch controlling lamp current during positive half-cycle; synchronized with low-side N-channel device. Use Value: Low R_DS(on) minimizes conduction loss at 2–5 A peak, while fast t_f ensures clean zero-voltage switching transitions.	Use Scenario: Enabling/disabling 12 V or 24 V subsystems (e.g., sensor arrays, display modules) in industrial HMIs. IC Role / Device Role / Timing Role: High-side power switch controlled by microcontroller GPIO with level-shifting circuitry. Use Value: Negative V_GS(th) allows direct interface with -5 V or -3.3 V gate drivers; SO-8 footprint supports automated assembly and thermal relief.
DC-DC Synchronous Buck (High-Side)	Hot-Swap Controller (P-FET Driver)
Use Scenario: Upper switch in non-isolated buck converter supplying 3.3 V or 5 V from 12 V input in telecom power modules. IC Role / Device Role / Timing Role: Main power switch operating at 300–500 kHz; duty cycle modulated by PWM controller. Use Value: 9 nC Q_g reduces gate drive losses; low C_oss (120 pF) maintains efficiency across wide V_DS range.	Use Scenario: Input protection FET in hot-swap card cages for server backplanes or modular instrumentation. IC Role / Device Role / Timing Role: Inrush-limiting P-MOSFET controlled by dedicated hot-swap IC (e.g., LTC4215). Use Value: 100 % UIS testing ensures survivability during live-insertion transients; R_DS(on) tolerance supports precise current limiting.

CCFL Inverter

High-Side Load Switch

Use Scenario: Driving cold cathode fluorescent lamp (CCFL) backlight in LCD panels using resonant half-bridge topology.

IC Role / Device Role / Timing Role: High-side P-channel switch controlling lamp current during positive half-cycle; synchronized with low-side N-channel device.

Use Value: Low R_DS(on) minimizes conduction loss at 2–5 A peak, while fast t_f ensures clean zero-voltage switching transitions.

Use Scenario: Enabling/disabling 12 V or 24 V subsystems (e.g., sensor arrays, display modules) in industrial HMIs.

IC Role / Device Role / Timing Role: High-side power switch controlled by microcontroller GPIO with level-shifting circuitry.

Use Value: Negative V_GS(th) allows direct interface with -5 V or -3.3 V gate drivers; SO-8 footprint supports automated assembly and thermal relief.

DC-DC Synchronous Buck (High-Side)

Hot-Swap Controller (P-FET Driver)

Use Scenario: Upper switch in non-isolated buck converter supplying 3.3 V or 5 V from 12 V input in telecom power modules.

IC Role / Device Role / Timing Role: Main power switch operating at 300–500 kHz; duty cycle modulated by PWM controller.

Use Value: 9 nC Q_g reduces gate drive losses; low C_oss (120 pF) maintains efficiency across wide V_DS range.

Use Scenario: Input protection FET in hot-swap card cages for server backplanes or modular instrumentation.

IC Role / Device Role / Timing Role: Inrush-limiting P-MOSFET controlled by dedicated hot-swap IC (e.g., LTC4215).

Use Value: 100 % UIS testing ensures survivability during live-insertion transients; R_DS(on) tolerance supports precise current limiting.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
IRF7410PbF	R_DS(on) = 0.055 Ω @ -10 V; Q_g = 11 nC; SO-8 but no exposed drain pad	Higher gate charge increases driver loss; lacks integrated thermal pad for high-power density layouts	Prefer SI4447DY-T1-E3 when board space and thermal management are constrained
DMN3026LSD-13	R_DS(on) = 0.042 Ω @ -10 V; V_DS = -30 V; dual P+P in SO-8; higher leakage (I_DSS = -5 µA)	Lower voltage rating limits use to ≤30 V systems; dual configuration adds routing complexity	Choose SI4447DY-T1-E3 for -40 V blocking margin and single-device simplicity in CCFL or load-switch roles

Compared with IRF7410PbF and DMN3026LSD-13, SI4447DY-T1-E3 offers superior thermal performance via exposed drain pads, tighter V_GS(th) distribution for predictable turn-on, and validated UIS robustness-making it preferred for high-reliability, thermally dense, or inductive-load applications.

Availability

SI4447DY-T1-E3 is available at Aetrix Electronics and suitable for CCFL inverters, high-side load switches, and DC-DC synchronous buck converters requiring stable component supply, consistent parametric performance, and long-term manufacturing continuity.

Supply support for SI4447DY-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, specializing in MOSFETs, diodes, optoelectronics, and passive components with emphasis on reliability, power efficiency, and miniaturization.

The Si4447DY belongs to Vishay's TrenchFET® P-channel power MOSFET product line, engineered for high-efficiency, high-density power management in lighting, industrial controls, and portable electronics.

FAQ

What is the maximum continuous drain current for SI4447DY-T1-E3 at 70 °C ambient temperature?

The SI4447DY-T1-E3 supports -3.6 A continuous drain current at T_A = 70 °C under standard mounting conditions (1" × 1" FR4 board). This value is derived from the Absolute Maximum Ratings table and accounts for thermal derating due to reduced heat dissipation at elevated ambient temperatures. The SI4447DY-T1-E3 must be used within this limit to ensure safe junction temperature operation below 150 °C.

Does SI4447DY-T1-E3 have a built-in body diode, and what are its forward voltage characteristics?

Yes, SI4447DY-T1-E3 integrates a body diode with V_SD = -0.79 to -1.2 V at I_S = -1.7 A and T_J = 25 °C. Its reverse recovery time (t_rr) is 27–45 ns and Q_rr is 17–26 nC, enabling efficient freewheeling in buck or flyback topologies. These values are measured under specified test conditions and are confirmed in the "Diode Forward Voltage" and "Dynamic" sections of the SI4447DY-T1-E3 datasheet.

Can SI4447DY-T1-E3 be driven directly by a 3.3 V microcontroller GPIO pin?

No-SI4447DY-T1-E3 requires a negative gate-to-source voltage to turn on, with V_GS(th) ranging from -0.8 to -2.2 V. A 3.3 V GPIO alone cannot produce the required negative bias. To drive SI4447DY-T1-E3 from a 3.3 V MCU, a level-shifting circuit (e.g., charge pump or dedicated gate driver like TC4427) must generate ≥-4.5 V at the gate relative to source. This is essential for achieving specified R_DS(on) and avoiding partial turn-on.

What is the thermal resistance from junction to foot (R_thJF) for SI4447DY-T1-E3, and why does it matter?

The SI4447DY-T1-E3 has R_thJF = 30–40 °C/W (steady-state), measured from junction to the exposed drain pad (pins 1–4). This parameter matters because it defines the dominant thermal path when the device is soldered to a copper pour or heatsink. Lower R_thJF enables higher power dissipation without exceeding T_J(max) = 150 °C-critical in compact CCFL inverters or high-side switches where airflow is limited.

Is SI4447DY-T1-E3 halogen-free, and how is that verified?

SI4447DY-T1-E3 is not halogen-free; only the variant SI4447DY-T1-GE3 carries that designation. Per Vishay documentation (S09-0322-Rev. B), the "-E3" suffix indicates lead-free compliance per JEDEC J-STD-609, while "-GE3" adds halogen-free status per IEC 61249-2-21. This distinction is explicitly stated in the Ordering Information section of the SI4447DY-T1-E3 datasheet.

SI4447DY-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:: P-Channel

Technology:: MOSFET (Metal Oxide)

Drain to Source Voltage (Vdss):: 40 V

Current - Continuous Drain (Id) @ 25°C:: 3.3A (Ta)

Drive Voltage (Max Rds On, Min Rds On):: 15V, 10V

Rds On (Max) @ Id, Vgs:: 72mOhm @ 4.5A, 15V

Vgs(th) (Max) @ Id:: 2.2V @ 250µA

Gate Charge (Qg) (Max) @ Vgs:: 14 nC @ 4.5 V

Vgs (Max):: ±16V

Input Capacitance (Ciss) (Max) @ Vds:: 805 pF @ 20 V

FET Feature:: -

Power Dissipation (Max):: 1.1W (Ta)

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

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 8-SOIC

SI4447DY-T1-E3 FAQ

1.How can I place an order for SI4447DY-T1-E3 through Aetrix?

Please submit a Request for Quotation (RFQ) for SI4447DY-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 SI4447DY-T1-E3 reliable?

The price and inventory of SI4447DY-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 SI4447DY-T1-E3 is usually 5 days.

3.What payment methods are accepted for SI4447DY-T1-E3?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SI4447DY-T1-E3 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for SI4447DY-T1-E3?

SI4447DY-T1-E3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your SI4447DY-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 SI4447DY-T1-E3?

For technical support, including SI4447DY-T1-E3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SI4447DY-T1-E3 requirements.

6.How does Aetrix verify that SI4447DY-T1-E3 is sourced from the original manufacturer or authorized distributors?

All SI4447DY-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 SI4447DY-T1-E3 meets industry standards.

7.What is the process for return or replacement of SI4447DY-T1-E3?

All SI4447DY-T1-E3 units undergo pre-shipment inspection (PSI). If there is an issue with SI4447DY-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 SI4447DY-T1-E3 part is unused and in its original packaging.

Return procedure for SI4447DY-T1-E3:

1.Submit a request within 90 days.

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

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