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Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > Voltage Reference

Semtech Corporation SC4437SK-3.3TRT

Name: SC4437SK-3.3TRT
Brand: Semtech Corporation
SKU: SC4437SK-3.3TRT
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: SC4437SK-3.3TRT

Manufacturer:: Semtech Corporation

Category:: Voltage Reference

Package:: TO-236-3, SC-59, SOT-23-3

Datasheet:: SC4437SK-3.3TRT.pdf

Description:: IC VREF SERIES 1% SOT23-3

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Product details

Overview

SC4437SK-3.3TRT from Semtech is a transient diverting suppressor (TDS) designed for high-energy EOS protection of 3.3V I/O or power lines in USB, industrial, and IoT interfaces. It delivers ±30kV IEC 61000-4-2 ESD immunity, clamps at 5.8V (IPP = 24A), maintains <20mΩ dynamic resistance, and operates from –40°C to +125°C in a 1.6mm × 1.6mm DFN-6 package.

For engineers reviewing the SC4437SK-3.3TRT datasheet, pinout, applications, or equivalent options, key selection criteria include clamping voltage stability across temperature, low capacitance (175pF @ 22V), ultra-low dynamic resistance, and compatibility with 3.3V bus protection in space-constrained USB Type-C and load switch designs.

Technical Context

The SC4437SK-3.3TRT uses a surge-rated FET as its primary protection element, activated by a precision trigger circuit that turns on the shunt path when transient voltage exceeds breakdown. Unlike conventional TVS diodes, its clamping voltage remains nearly constant (5.8V typical) across the full rated peak pulse current range (up to 24A) due to decreasing R_DS(on) under surge conditions.

It features a 3.3V working voltage (V_RWM), 5.2V typical breakdown (V_BR), and 175pF junction capacitance at 3.3V bias - optimized for high-speed digital interfaces where signal integrity and low loading are critical. Its DFN-6 layout assigns pins 1–3 to GND and pins 4–6 to IN, requiring all six pins to be connected for full 24A surge capability.

Key Specifications

Parameter	Value and Actual Design Meaning
Working Voltage (V_RWM)	3.3 V - matches standard 3.3V logic and interface rails without derating.
Clamping Voltage (V_C)	5.8 V @ IPP = 24A - stays below 6V threshold to protect 3.3V ICs with margin.
Peak Pulse Current (I_PP)	24 A (tp = 8/20μs) - meets IEC 61000-4-5 Level 3 surge immunity requirements.
ESD Withstand	±30 kV contact & air (IEC 61000-4-2) - exceeds industrial and USB PD ESD robustness needs.
Junction Capacitance (C_J)	175 pF @ VR = 3.3V, 1MHz - low enough for USB 2.0 and industrial control lines.
Dynamic Resistance (R_DYN)	20 mΩ - enables flat clamping response and minimal voltage rise under surge.
Operating Temperature	–40°C to +125°C - supports extended-range operation in automotive-adjacent and industrial environments.

Pinout & Package

SC4437SK-3.3TRT is housed in a Pb-free, RoHS-compliant DFN-6 package measuring 1.6 mm × 1.6 mm × 0.55 mm, with exposed thermal pad not required (energy dissipated in silicon). All six terminals must be soldered: pins 1–3 serve as low-inductance ground return paths; pins 4–6 form a parallel input node for the protected line.

Pin/Terminal	Circuit Role	Design Meaning
1, 2, 3	GND	Common ground connection - all three must be tied to PCB ground plane via multiple vias to minimize surge loop inductance.
4, 5, 6	IN	Parallel-connected input node - connects directly to protected 3.3V line (e.g., USB VBUS, load switch input); all three pins conduct surge current jointly.

Key Features

Feature	Design Value
FET-based transient diversion	Replaces conventional TVS with active shunt switching - eliminates linear V_C vs. I_PP drift and improves temperature stability.
Constant clamping voltage	V_C = 5.8V across –40°C to +125°C and 1A–24A - ensures predictable protection margin under worst-case thermal and surge conditions.
Low dynamic resistance	R_DYN = 20 mΩ - reduces voltage overshoot during fast-rising transients (e.g., ESD) and minimizes power dissipation in silicon.
High EFT immunity	±4 kV per IEC 61000-4-4 (5/50 ns, 100 kHz/5 kHz) - protects against repetitive burst noise in industrial control and power supply environments.
Space-efficient packaging	1.6 mm × 1.6 mm footprint - saves >60% board area versus SO-8 or SOT-23 TVS alternatives while supporting same surge rating.

Applications

USB Type-C Power Delivery Interface	Industrial Load Switch Input Protection
Use Scenario: Protecting 3.3V auxiliary power rails and control signals in USB Type-C receptacles supporting PD negotiation and VCONN sourcing. IC Role / Device Role / Timing Role: Transient diverting suppressor placed between VCONN or CC line and ground to clamp EOS events before reaching PD controller or level-shifter ICs. Use Value: Maintains 5.8V clamping at 24A and 125°C - prevents latch-up or gate oxide damage in 3.3V PD controllers where traditional TVS would exceed safe voltage margins.	Use Scenario: Safeguarding the input of 3.3V-rated load switches (e.g., TPS229xx, AP22653) in programmable logic controllers and remote I/O modules. IC Role / Device Role / Timing Role: Primary front-end surge protector absorbing lightning-induced surges and hot-swap transients on switched 3.3V distribution buses. Use Value: 20 mΩ R_DYN limits voltage overshoot to <0.5V above clamping during 10A/µs dI/dt events - avoids false overvoltage shutdown in load switch OVP circuitry.
IoT Sensor Node Power Bus	Medical Diagnostic Equipment Data Lines
Use Scenario: Securing 3.3V power inputs of battery-powered edge sensors exposed to ESD during field servicing or connector mating. IC Role / Device Role / Timing Role: Single-device EOS solution replacing multi-component TVS+RC filters on compact sensor PCBs with limited real estate. Use Value: 175pF capacitance adds negligible loading to 3.3V rail - avoids destabilizing LDO feedback or interfering with ADC reference decoupling.	Use Scenario: Protecting isolated 3.3V communication lines (e.g., UART, SPI) linking FPGA-based acquisition modules to analog front-ends in portable diagnostic gear. IC Role / Device Role / Timing Role: Low-capacitance transient suppressor placed at board edge to prevent coupling of ESD into sensitive analog signal chains. Use Value: ±30kV ESD rating and stable 5.8V clamping ensure immunity to operator-handling discharges without degrading signal rise time (<1 ns impact).

USB Type-C Power Delivery Interface

Industrial Load Switch Input Protection

Use Scenario: Protecting 3.3V auxiliary power rails and control signals in USB Type-C receptacles supporting PD negotiation and VCONN sourcing.

IC Role / Device Role / Timing Role: Transient diverting suppressor placed between VCONN or CC line and ground to clamp EOS events before reaching PD controller or level-shifter ICs.

Use Value: Maintains 5.8V clamping at 24A and 125°C - prevents latch-up or gate oxide damage in 3.3V PD controllers where traditional TVS would exceed safe voltage margins.

Use Scenario: Safeguarding the input of 3.3V-rated load switches (e.g., TPS229xx, AP22653) in programmable logic controllers and remote I/O modules.

IC Role / Device Role / Timing Role: Primary front-end surge protector absorbing lightning-induced surges and hot-swap transients on switched 3.3V distribution buses.

Use Value: 20 mΩ R_DYN limits voltage overshoot to <0.5V above clamping during 10A/µs dI/dt events - avoids false overvoltage shutdown in load switch OVP circuitry.

IoT Sensor Node Power Bus

Medical Diagnostic Equipment Data Lines

Use Scenario: Securing 3.3V power inputs of battery-powered edge sensors exposed to ESD during field servicing or connector mating.

IC Role / Device Role / Timing Role: Single-device EOS solution replacing multi-component TVS+RC filters on compact sensor PCBs with limited real estate.

Use Value: 175pF capacitance adds negligible loading to 3.3V rail - avoids destabilizing LDO feedback or interfering with ADC reference decoupling.

Use Scenario: Protecting isolated 3.3V communication lines (e.g., UART, SPI) linking FPGA-based acquisition modules to analog front-ends in portable diagnostic gear.

IC Role / Device Role / Timing Role: Low-capacitance transient suppressor placed at board edge to prevent coupling of ESD into sensitive analog signal chains.

Use Value: ±30kV ESD rating and stable 5.8V clamping ensure immunity to operator-handling discharges without degrading signal rise time (<1 ns impact).

Equivalent & Alternatives

The following parts are listed as comparable options for similar transient suppression applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
TDS2211P	22V V_RWM, 27.5V clamping @ 24A, 175pF - higher working voltage and clamping, same package.	Targeted at 20–22V USB PD bus protection, not 3.3V logic lines.	Select only if protecting >20V rails; incompatible with 3.3V ICs due to excessive clamping voltage.
uClamp3311ZA	3.3V V_RWM, 7.5V clamping @ 12A, 120pF - lower surge rating and higher clamping than SC4437SK-3.3TRT.	Suitable for lower-energy ESD-only scenarios (e.g., button inputs), not industrial surge.	Use where space or cost constraints preclude SC4437SK-3.3TRT; verify 7.5V clamping is acceptable for downstream 3.3V ICs.

Compared with TDS2211P and uClamp3311ZA, SC4437SK-3.3TRT uniquely combines 3.3V working voltage, 5.8V clamping at 24A, and 20mΩ dynamic resistance - enabling robust surge protection on 3.3V rails without compromising signal integrity or thermal margin.

Availability

SC4437SK-3.3TRT is available at Aetrix Electronics and suitable for USB Type-C interface protection, industrial load switch input hardening, and IoT sensor node power bus safeguarding requiring stable component supply and long-term lifecycle support.

Supply support for SC4437SK-3.3TRT 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

Semtech Corporation is a U.S.-based fabless semiconductor company specializing in high-performance analog and mixed-signal ICs for precision sensing, protection, and connectivity.

SC4437SK-3.3TRT belongs to Semtech's Transient Diverting Suppressor (TDS) family, engineered to replace conventional TVS diodes with FET-based active clamping for superior surge immunity in space-constrained, thermally demanding applications.

FAQ

What is the maximum clamping voltage of SC4437SK-3.3TRT under IEC 61000-4-5 surge conditions?

The SC4437SK-3.3TRT clamps at 5.8 V (typical) and 6.0 V (max) when subjected to a 24 A, 8/20 µs surge per IEC 61000-4-5. This value is guaranteed across –40°C to +125°C and reflects the device's FET-based active clamping architecture - not a fixed V_BR + I_PP×R_DYN relationship. The SC4437SK-3.3TRT maintains this tight clamping window even at full rated current and temperature extremes.

Can SC4437SK-3.3TRT be used to protect 3.3V USB data lines like D+/D–?

No - SC4437SK-3.3TRT is not intended for high-speed data line protection. Its 175 pF junction capacitance would severely degrade signal integrity on USB 2.0 differential pairs. For D+/D– lines, Semtech recommends low-capacitance TVS devices such as RClamp3371ZC (<0.25 pF). The SC4437SK-3.3TRT is designed for 3.3V power rails, VCONN, CC, or other low-frequency I/O where capacitance is not a limiting factor.

Does SC4437SK-3.3TRT require a thermal pad or heatsink on the PCB?

No. SC4437SK-3.3TRT dissipates surge energy within its silicon die and does not rely on external thermal conduction. The DFN-6 package has no exposed thermal pad, and the datasheet explicitly states "no thermal pad is needed." Layout best practice is to connect all GND pins (1–3) to a solid ground plane using multiple vias - not to add copper pour for heat sinking.

How does SC4437SK-3.3TRT differ from standard TVS diodes in clamping behavior?

Unlike standard TVS diodes whose clamping voltage rises linearly with peak current (V_C = V_BR + I_PP×R_DYN), the SC4437SK-3.3TRT uses a triggered FET to achieve near-constant clamping. Its V_C stays at ~5.8 V from 1 A to 24 A because R_DS(on) decreases under surge, counteracting current-driven voltage rise. This eliminates the need to overspecify I_PP to meet voltage thresholds - a key advantage of the SC4437SK-3.3TRT.

Is SC4437SK-3.3TRT compliant with RoHS and halogen-free standards?

Yes. SC4437SK-3.3TRT is Pb-free, halogen-free, and fully compliant with RoHS and WEEE directives. Its molding compound meets UL 94V-0 flammability rating, and the lead finish is lead-free. The device is supplied in tape-and-reel packaging (3,000 units per 7-inch reel), with marking code "T33" followed by date code - consistent with Semtech's environmental compliance program for the SC4437SK-3.3TRT family.

SC4437SK-3.3TRT Specifications

Product attributes: Attribute value

Manufacturer:: Semtech Corporation

Package/Case:: TO-236-3, SC-59, SOT-23-3

Series:: -

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Reference Type:: Series

Output Type:: Fixed

Voltage - Output (Min/Fixed):: 3.3V

Voltage - Output (Max):: -

Current - Output:: 20 mA

Tolerance:: ±1%

Temperature Coefficient:: 120ppm/°C

Noise - 0.1Hz to 10Hz:: -

Noise - 10Hz to 10kHz:: -

Voltage - Input:: 4.2V ~ 28V

Current - Supply:: 220µA

Current - Cathode:: -

Operating Temperature:: -40°C ~ 125°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: SOT-23-3

SC4437SK-3.3TRT FAQ

1.How can I place an order for SC4437SK-3.3TRT through Aetrix?

Please submit a Request for Quotation (RFQ) for SC4437SK-3.3TRT 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 SC4437SK-3.3TRT reliable?

The price and inventory of SC4437SK-3.3TRT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SC4437SK-3.3TRT is usually 5 days.

3.What payment methods are accepted for SC4437SK-3.3TRT?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SC4437SK-3.3TRT transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for SC4437SK-3.3TRT?

SC4437SK-3.3TRT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your SC4437SK-3.3TRT 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 SC4437SK-3.3TRT?

For technical support, including SC4437SK-3.3TRT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SC4437SK-3.3TRT requirements.

6.How does Aetrix verify that SC4437SK-3.3TRT is sourced from the original manufacturer or authorized distributors?

All SC4437SK-3.3TRT 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 SC4437SK-3.3TRT meets industry standards.

7.What is the process for return or replacement of SC4437SK-3.3TRT?

All SC4437SK-3.3TRT units undergo pre-shipment inspection (PSI). If there is an issue with SC4437SK-3.3TRT, 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 SC4437SK-3.3TRT part is unused and in its original packaging.

Return procedure for SC4437SK-3.3TRT:

1.Submit a request within 90 days.

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

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