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Home > Products > Discrete Semiconductor Products > Diodes > Rectifiers > Single Diodes

STMicroelectronics STPS3L40UFN

Name: STPS3L40UFN
Brand: STMicroelectronics
SKU: STPS3L40UFN
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: STPS3L40UFN

Manufacturer:: STMicroelectronics

Category:: Single Diodes

Package:: DO-221AA, SMB Flat Leads

Datasheet:: STPS3L40UFN.pdf

Description:: DIODE SCHOTTKY 40V 3A SMBFLAT

Quantity:: RFQ Add To RFQ list

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Inventory:4,787

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Product details

Overview

STPS3L40UFN from STMicroelectronics is a 40 V, 3 A low-drop Schottky rectifier in SMB Flat Notch package, designed for high-frequency DC/DC converters and switch-mode power supplies. It delivers typ. 0.40 V forward voltage at 3 A and 125 °C, features avalanche rating up to 95 W (10 µs), and achieves junction-to-lead thermal resistance of 15 °C/W - enabling compact, efficient telecom and TV power supply designs.

For engineers reviewing the STPS3L40UFN datasheet, STPS3L40UFN pinout, STPS3L40UFN application, or STPS3L40UFN equivalent, key selection criteria include its 40 V repetitive peak reverse voltage, 3 A average forward current capability at 120 °C ambient (SMB Flat Notch), negligible switching losses, and ECOPACK2-compliant lead-free packaging for surface-mount reliability.

Technical Context

This Schottky rectifier operates with zero minority-carrier storage, eliminating reverse recovery time and associated switching losses. Its metal–semiconductor junction enables low VF and high-speed unidirectional conduction essential for >100 kHz DC/DC topologies.

Thermal performance is optimized via low R_th(j-l) (15 °C/W) and avalanche-rated ruggedness (95 W, 10 µs pulse), supporting robust operation under transient overvoltage and surge conditions without external snubbers.

Key Specifications

Parameter	Value and Actual Design Meaning
V_RRM	40 V - Maximum reverse blocking voltage; ensures safe operation in 36 V nominal bus systems with margin.
I_F(AV)	3 A at T_L = 120 °C (SMB Flat Notch) - Continuous DC output current capability without heatsink in typical SMPS layouts.
V_F(typ.)	0.40 V @ 3 A, 125 °C - Directly reduces conduction loss to ~1.2 W, improving efficiency in high-current 5–12 V rails.
R_th(j-l)	15 °C/W - Enables direct PCB copper pad thermal coupling; simplifies thermal design vs. discrete heatsink mounting.
I_FSM	75 A (10 ms sinusoidal) - Withstands inrush and short-circuit surges common in AC/DC front-end and battery charger inputs.
P_ARM	95 W @ 10 µs, T_j = 125 °C - Avalanche energy rating allows safe clamping of inductive kickback in flyback and LLC resonant converters.

Pinout & Package

SMB Flat Notch package: surface-mount, lead-free, UL94 V0 epoxy body (3.30–3.95 mm length × 5.20–5.60 mm width × 0.90–1.10 mm height), optimized for automated placement and reflow soldering on FR4 boards.

Pin/Terminal	Circuit Role	Design Meaning
Anode (A)	Current entry terminal	Connected to input/high-side node; must be routed with low-inductance trace to minimize voltage spikes during switching.
Cathode (K)	Current exit terminal	Connected to output/low-side node; serves as reference for output filtering and feedback sensing in buck/flyback outputs.

Key Features

Feature	Design Value
Negligible switching losses	No reverse recovery charge (Q_rr ≈ 0); eliminates turn-off loss and EMI in high-frequency (>200 kHz) converters.
Low forward voltage drop	V_F = 0.40 V typ. @ 3 A, 125 °C - Reduces conduction loss by ≥30% vs. standard silicon diodes in same footprint.
Avalanche rated	95 W peak avalanche power (10 µs) - Enables reliable operation without external TVS in cost-sensitive consumer power supplies.
Low thermal resistance	R_th(j-l) = 15 °C/W - Allows full 3 A current handling with only 45 °C temperature rise above PCB pad at 120 °C ambient.

Applications

Telecom Power Supply

Set-Top Box Power Supply

Use Scenario: Secondary-side rectification in isolated 48 V input, 12 V/3 A output DC/DC modules for PoE-powered base stations.

IC Role / Device Role / Timing Role: High-efficiency synchronous rectifier replacement; conducts during positive half-cycle of transformer secondary voltage.

Use Value: 0.40 V V_F minimizes dropout and improves load regulation under dynamic 0–3 A step loads.

Use Scenario: Output rectification in non-isolated buck-derived 12 V → 5 V/3 A converter for HDMI interface and tuner subsystems.

IC Role / Device Role / Timing Role: Unidirectional freewheeling path during low-side MOSFET off-time; critical for continuous conduction mode stability.

Use Value: Avalanche rating absorbs leakage inductance spikes from coupled inductors, preventing cathode overvoltage failure.

TV Power Supply

Battery Charger

Use Scenario: Standby 5 V rail rectification in multi-output flyback PSUs powering microcontrollers and remote control receivers.

IC Role / Device Role / Timing Role: Low-loss output diode operating continuously at light load (10–100 mA), where V_F dominates efficiency.

Use Value: 0.40 V V_F at 125 °C maintains >85% standby efficiency even at elevated board temperatures.

Use Scenario: Output rectification in 19 V → 12.6 V/3 A Li-ion charger for portable projectors and smart displays.

IC Role / Device Role / Timing Role: Primary output rectifier in constant-voltage stage; handles full charging current with minimal thermal derating.

Use Value: R_th(j-l) = 15 °C/W enables direct thermal coupling to 2 cm² copper pour, avoiding discrete heatsinks.

Equivalent & Alternatives

The following parts are listed as comparable options for similar Schottky rectifier applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
SS34 (Diodes Inc.)	Same 40 V V_RRM, 3 A I_F(AV), but VF = 0.55 V typ. @ 3 A, 25 °C; no avalanche rating; SMB package (no notch).	Lacks avalanche ruggedness; unsuitable for flyback or inductive-load circuits with voltage transients.	Select only for low-cost, low-stress linear or low-frequency buck applications where surge immunity is not required.
SB340 (SMC, Vishay)	Same 40 V/3 A rating, VF = 0.52 V typ. @ 3 A, 25 °C; SMC package (larger footprint); R_th(j-l) = 18 °C/W.	Higher thermal resistance requires larger copper area or heatsink for same current; not drop-in compatible due to SMC vs. SMB Flat Notch footprint.	Choose when board layout accommodates SMC and higher thermal mass is acceptable; avoid if space-constrained or high-density routing is needed.

Compared with SS34 and SB340, STPS3L40UFN offers lower VF at elevated temperature, certified avalanche capability, and SMB Flat Notch's precise placement alignment - making it optimal for thermally dense, high-reliability consumer power supplies where size, efficiency, and transient robustness are jointly critical.

Availability

STPS3L40UFN is available at Aetrix Electronics and suitable for telecom power supply, set-top box power supply, and TV power supply requiring stable component supply across long-life consumer electronics programs.

Supply support for STPS3L40UFN 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing analog, power, MCU, and sensor solutions for industrial, automotive, and consumer markets.

STPS3L40UFN belongs to ST's high-efficiency Schottky rectifier product line, engineered specifically for high-frequency, space-constrained switch-mode power supplies where low VF, thermal efficiency, and avalanche ruggedness are mandatory.

FAQ

What is the maximum junction temperature for STPS3L40UFN?

The absolute maximum operating junction temperature is +150 °C, as specified in Table 1 of DS1947 Rev 5. Operation at this limit requires strict thermal management: PCB copper area must maintain junction-to-ambient thermal resistance below 50 °C/W, and ambient temperature must not exceed 120 °C at the device location.

Is STPS3L40UFN RoHS and REACH compliant?

Yes - STPS3L40UFN is manufactured as an ECOPACK2 component, meeting RoHS Directive 2011/65/EU and REACH Regulation (EC) No. 1907/2006. The SMB Flat Notch package uses lead-free terminations and halogen-free epoxy, verified per ST's published environmental compliance documentation.

Can STPS3L40UFN replace a standard PN-junction rectifier in an existing design?

Yes, provided the circuit does not rely on reverse recovery for timing or snubbing functions. STPS3L40UFN has no reverse recovery time, so it eliminates associated switching loss and EMI - but may require minor output capacitor adjustment in some flyback designs due to faster voltage transitions.

What is the recommended PCB footprint for STPS3L40UFN?

The official footprint is defined in Figure 15 of DS1947 Rev 5: 5.84 mm × 1.20 mm pad length/width, with 3.44 mm center-to-center spacing and 2.07 mm pad-to-pad clearance. Use 1.20 mm solder mask opening and 0.3 mm stencil aperture for optimal reflow yield and void control.

STPS3L40UFN Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: ECOPACK®2

Package/Case:: DO-221AA, SMB Flat Leads

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Technology:: Schottky

Voltage - DC Reverse (Vr) (Max):: 40 V

Current - Average Rectified (Io):: 3A

Voltage - Forward (Vf) (Max) @ If:: 500 mV @ 3 A

Speed:: Fast Recovery =< 500ns, > 200mA (Io)

Reverse Recovery Time (trr):: -

Current - Reverse Leakage @ Vr:: 100 µA @ 40 V

Capacitance @ Vr, F:: -

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: SMBflat Notch

Operating Temperature - Junction:: 150°C

STPS3L40UFN FAQ

1.How can I place an order for STPS3L40UFN through Aetrix?

Please submit a Request for Quotation (RFQ) for STPS3L40UFN 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 STPS3L40UFN reliable?

The price and inventory of STPS3L40UFN are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for STPS3L40UFN is usually 5 days.

3.What payment methods are accepted for STPS3L40UFN?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for STPS3L40UFN transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for STPS3L40UFN?

STPS3L40UFN orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your STPS3L40UFN 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 STPS3L40UFN?

For technical support, including STPS3L40UFN datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your STPS3L40UFN requirements.

6.How does Aetrix verify that STPS3L40UFN is sourced from the original manufacturer or authorized distributors?

All STPS3L40UFN 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 STPS3L40UFN meets industry standards.

7.What is the process for return or replacement of STPS3L40UFN?

All STPS3L40UFN units undergo pre-shipment inspection (PSI). If there is an issue with STPS3L40UFN, 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 STPS3L40UFN part is unused and in its original packaging.

Return procedure for STPS3L40UFN:

1.Submit a request within 90 days.

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

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