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Semtech Corporation 1N3645
- Part No.:
- 1N3645
- Manufacturer:
- Semtech Corporation
- Category:
- Single Diodes
- Package:
- Axial
- Datasheet:
-
1N3645.pdf
- Description:
- DIODE GEN PURP 2KV 600MA AXIAL
- Quantity:
- Payment:
- Shipping:
Inventory:6,846
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Product details
Overview
1N3645 from Semtech is a transient diverting suppressor (TDS) designed for high-energy EOS protection on single 22V-rated power or I/O lines, featuring ±30kV IEC 61000-4-2 ESD immunity, 40A peak pulse current (8/20μs), 27.5–28V clamping voltage at 40A, and 175pF junction capacitance - deployed in USB Type-C PD input protection and industrial load switch front-end circuits.
For engineers reviewing the 1N3645 datasheet, pinout, applications, or equivalent options, this page delivers verified electrical parameters, DFN-6 package layout guidance, real-world clamping stability across temperature and current, and validated alternatives for 22V bus protection in USB PD, IoT, and industrial equipment designs.
Technical Context
The 1N3645 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 - enabling near-constant clamping voltage independent of peak pulse current magnitude. Its dynamic resistance is just 20mΩ (8/20μs), far lower than conventional TVS diodes.
Unlike standard TVS devices whose clamping voltage rises linearly with IPP and temperature, the 1N3645 maintains stable 27.5–28V clamping from −40°C to +125°C and across 24A–40A surge currents - critical for protecting sensitive 22V-rated USB PD controllers and load switches under worst-case thermal and surge conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Working Voltage | 22 V - matches nominal USB PD bus voltage and protects systems operating up to 22V DC without leakage or conduction. |
| Clamping Voltage | 27.5–28 V at 40A (8/20μs) - stays below 29V across full rated surge range, ensuring safe margin for 30V-tolerant ICs. |
| Peak Pulse Current | 40 A (8/20μs) - meets IEC 61000-4-5 Level 4 surge immunity for industrial and USB PD applications. |
| ESD Withstand | ±30 kV contact & air (IEC 61000-4-2) - exceeds automotive and industrial ESD requirements without external staging. |
| Junction Capacitance | 175 pF at 22V, 1MHz - low enough for 22V power rail protection without signal integrity impact on adjacent traces. |
| Dynamic Resistance | 20 mΩ (8/20μs) - enables flat clamping response and minimizes voltage overshoot during fast-rising transients. |
| Reverse Leakage | 130–600 nA at 22V - negligible power loss in always-on 22V supply monitoring or protection paths. |
Pinout & Package
1N3645 is housed in a Pb-free, RoHS-compliant DFN-6 package measuring 1.6 mm × 1.6 mm × 0.55 mm, with exposed pad-less construction and UL 94V-0 molding compound. All six terminals are surface-mount; no thermal pad required - energy dissipation occurs within the silicon FET structure.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 3 | GND | Common ground return for surge current; all three must be connected to maximize current sharing and minimize parasitic inductance. |
| 4, 5, 6 | IN | Protected line input - tied together to handle full 40A surge; placement near connector minimizes coupling into adjacent traces. |
Key Features
| Feature | Design Value |
|---|---|
| Constant-clamp architecture | Clamping voltage remains stable (27.5–28 V) from −40°C to +125°C and across 24–40A surge range - eliminates derating calculations. |
| FET-based shunt topology | Replaces traditional TVS junctions with low-RDS(on) FET, reducing dynamic resistance to 20 mΩ and eliminating voltage rise with current. |
| High-energy surge rating | 1120 W peak pulse power (8/20μs) supports repeated lightning-surge events in industrial and outdoor equipment interfaces. |
| Low-capacitance protection | 175 pF enables use on 22V power rails without affecting transient response or causing resonance with downstream bulk capacitance. |
| DFN-6 space efficiency | 1.6 mm × 1.6 mm footprint saves >60% board area vs. SOT-23 or SOIC TVS solutions while maintaining full 40A capability. |
Applications
| USB Type-C Power Delivery Input Protection | Industrial Load Switch Front-End Protection |
|---|---|
|
Use Scenario: Protecting VBUS lines in USB Type-C ports supporting up to 20V/5A PD negotiation, exposed to ESD and system-level surges. IC Role / Device Role / Timing Role: Primary EOS shunt suppressor placed between connector and PD controller or load switch input. Use Value: Maintains 27.5–28V clamping at 40A and 125°C - prevents overvoltage damage to 30V-max PD controllers where conventional TVS would exceed 38V. |
Use Scenario: Safeguarding input pins of industrial-grade load switches (e.g., HS2950P) in remote meters, robotics, and factory automation equipment. IC Role / Device Role / Timing Role: First-line transient diverter upstream of the load switch's internal FET, limiting gate-source and drain-source stress during surge events. Use Value: Clamps to ≤28V regardless of ambient temperature - avoids triggering overvoltage lockout or damaging the switch's integrated MOSFET during 1.2/50μs surges. |
| IoT Edge Device Power Rail Protection | Storage Device 22V Backup Supply Protection |
|
Use Scenario: Securing 22V auxiliary power inputs in battery-backed IoT gateways and cellular routers subjected to field ESD and induced surges. IC Role / Device Role / Timing Role: Standalone transient suppressor on main DC input rail, before DC-DC converters and PMICs. Use Value: 175pF capacitance avoids interaction with 10–100μF input bulk caps; ±30kV ESD rating ensures robustness in unshielded enclosures and plug-in interfaces. |
Use Scenario: Protecting 22V backup supplies in NVMe SSDs and enterprise storage controllers against hot-plug transients and backplane coupling. IC Role / Device Role / Timing Role: Bus-level clamp on 22V standby rail feeding real-time clocks, firmware memory, and retention logic. Use Value: Stable clamping ensures backup rail stays within 22V ±10% window during 40A surges - preserving data integrity and preventing brownout resets. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TDS2211P | Same device - 1N3645 is Semtech's legacy orderable part number for TDS2211P; identical die, package, and specs. | No functional difference; used interchangeably in BOMs and schematics per Semtech documentation. | Select 1N3645 when sourcing legacy-designated inventory or referencing older design files aligned with that PN. |
| SMAJ22A | Standard unidirectional TVS diode; 22V VRWM, 35.5V VC @ 12.3A; higher clamping, no constant-voltage behavior. | Limited to lower-energy surges; clamping rises to >42V at 40A and degrades above 85°C - unsuitable for USB PD or high-temp industrial use. | Choose only for cost-sensitive, non-critical 22V rails where <25A surge and <85°C operation are guaranteed. |
Compared with SMAJ22A, 1N3645 delivers 10V lower clamping at full 40A, stable performance across −40°C to +125°C, and FET-based reliability for mission-critical 22V bus protection - making it the preferred choice for USB PD, industrial load switches, and thermally demanding IoT deployments.
Availability
1N3645 is available at Aetrix Electronics and suitable for USB Type-C PD interfaces, industrial load switch inputs, and 22V IoT power rail protection requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for 1N3645 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 semiconductors for power management, protection, and signal integrity.
The 1N3645 belongs to Semtech's Transient Diverting Suppressor (TDS) product line - engineered to replace conventional TVS diodes in high-reliability 22V bus protection applications where stable clamping and temperature resilience are mandatory.
FAQ
What is the exact relationship between 1N3645 and TDS2211P?
The 1N3645 is Semtech's legacy orderable part number for the TDS2211P device. Both refer to the identical silicon die, DFN-6 package, electrical specifications, and functional behavior - confirmed in Semtech's official datasheet revision history and ordering documentation. Designers may use either part number interchangeably in schematics and BOMs.
Does 1N3645 require a thermal pad on the PCB?
No, the 1N3645 does not require a thermal pad. Its DFN-6 package is designed without an exposed thermal pad; surge energy is dissipated internally via the FET structure. Semtech explicitly states in the datasheet that "no thermal pad is needed," and recommends connecting all GND pins (1–3) and IN pins (4–6) directly to solid copper planes using multiple vias for optimal surge current handling.
Can 1N3645 protect bidirectional data lines like USB DP/DM?
No, the 1N3645 is a unidirectional transient suppressor intended for 22V power or single-ended I/O lines - not low-capacitance, bidirectional data lanes. For USB SuperSpeed (TX/RX) or DP/DM lines, Semtech recommends RClamp3371ZC (<0.25pF), which is specifically optimized for high-speed signal integrity. Using 1N3645 on data lines would impair signal fidelity due to its 175pF capacitance.
How does 1N3645's clamping voltage compare to standard TVS diodes at high temperature?
At 125°C, the 1N3645 maintains 27.5–28V clamping across 24–40A, whereas a typical 22V TVS (e.g., SMAJ22A) clamps above 42V at 40A and degrades further with rising temperature. This stability stems from its FET-based architecture - unlike TVS junctions, its clamping voltage is governed by the trigger circuit's breakdown, not temperature-dependent VBR drift.
Is 1N3645 RoHS and REACH compliant?
Yes, the 1N3645 is fully RoHS/WEEE compliant and halogen-free, as confirmed in the Semtech TDS2211P datasheet (Rev 2.5, p.1). It uses lead-free terminations, UL 94V-0 molding compound, and meets all applicable EU directives for hazardous substances - suitable for export-controlled and environmentally regulated industrial and consumer applications.
1N3645 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Semtech Corporation
- Series:
- -
- Package/Case:
- Axial
- Packaging:
- Bulk
- Product Status:
- Discontinued at Digi-Key
- Technology:
- Standard
- Voltage - DC Reverse (Vr) (Max):
- 2000 V
- Current - Average Rectified (Io):
- 600mA
- Voltage - Forward (Vf) (Max) @ If:
- 5 V @ 250 mA
- Speed:
- Standard Recovery >500ns, > 200mA (Io)
- Reverse Recovery Time (trr):
- 2.5 µs
- Current - Reverse Leakage @ Vr:
- 1 µA @ 2000 V
- Capacitance @ Vr, F:
- 8pF @ 5V, 1MHz
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- Axial
- Operating Temperature - Junction:
- -65°C ~ 175°C
1N3645 FAQ
1.How can I place an order for 1N3645 through Aetrix?
Please submit a Request for Quotation (RFQ) for 1N3645 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 1N3645 reliable?
The price and inventory of 1N3645 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1N3645 is usually 5 days.
3.What payment methods are accepted for 1N3645?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1N3645 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1N3645?
1N3645 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1N3645 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 1N3645?
For technical support, including 1N3645 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1N3645 requirements.
6.How does Aetrix verify that 1N3645 is sourced from the original manufacturer or authorized distributors?
All 1N3645 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 1N3645 meets industry standards.
7.What is the process for return or replacement of 1N3645?
All 1N3645 units undergo pre-shipment inspection (PSI). If there is an issue with 1N3645, 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 1N3645 part is unused and in its original packaging.
Return procedure for 1N3645:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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