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Semtech Corporation 1N6638
- Part No.:
- 1N6638
- Manufacturer:
- Semtech Corporation
- Category:
- Single Diodes
- Package:
- Axial
- Datasheet:
-
1N6638.pdf
- Description:
- DIODE GEN PURP 125V 300MA AXIAL
- Quantity:
- Payment:
- Shipping:
Inventory:4,850
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Product details
Overview
1N6638 from Semtech is a transient diverting suppressor (TDS) designed for high-energy EOS protection of 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 ultra-low 20mΩ dynamic resistance. It protects USB PD, USB Type-C VBus, and load switch inputs in industrial and portable electronics.
For engineers reviewing the 1N6638 datasheet, pinout, applications, or equivalent options, this page delivers verified electrical specs, DFN-6 package layout guidance, clamping stability across temperature and current, and real-world implementation insights for EOS-critical bus protection.
Technical Context
The 1N6638 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-27.5–28V across 24A to 40A and −40°C to +125°C-due to decreasing RDS(on) under surge.
It operates with a 22V reverse stand-off voltage (VRWM) and 25–27.9V breakdown (VBR), exhibits only 130–600nA leakage at 22V, and maintains 175pF junction capacitance at 22V/1MHz-enabling robust protection without signal integrity compromise on high-speed power rails.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reverse Stand-Off Voltage | 22V - defines maximum continuous operating voltage before clamping activation |
| Clamping Voltage | 27.5–28V at 40A (8/20μs) - ensures protected ICs see ≤28V during worst-case surges |
| Peak Pulse Current | 40A (8/20μs) - meets IEC 61000-4-5 Level 4 industrial surge immunity requirements |
| ESD Withstand | ±30kV contact & air (IEC 61000-4-2) - exceeds automotive and industrial ESD stress levels |
| Dynamic Resistance | 20mΩ - enables flat clamping curve and minimal voltage rise under increasing surge current |
| Junction Capacitance | 175pF at 22V/1MHz - low enough to avoid degrading 20V power rail stability or noise coupling |
Pinout & Package
1N6638 is housed in a Pb-free, RoHS-compliant DFN-6 package measuring 1.6mm × 1.6mm × 0.55mm with exposed thermal pad not required-energy is dissipated in the silicon FET structure. All six terminals must be connected per functional role for full 40A surge rating.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 3 | GND | Common ground return path for surge current; all three pins must be connected to minimize inductance |
| 4, 5, 6 | IN | Protected line input (e.g., USB PD VBus); parallel connection ensures current sharing and full 40A capability |
Key Features
| Feature | Design Value |
|---|---|
| Constant clamping across current & temperature | 27.5–28V clamping maintained from −40°C to +125°C and 24A to 40A-no derating needed |
| FET-based shunt architecture | Replaces PN-junction TVS with active switching; eliminates linear VC = VBR + IPP×RDYN dependency |
| Low dynamic resistance | 20mΩ enables <1V voltage rise between 1A and 40A-critical for protecting 22V-tolerant controllers |
| High EFT immunity | ±4kV per IEC 61000-4-4 (5/50ns, 100kHz/5kHz) - protects against repetitive burst transients in industrial environments |
Applications
| USB Type-C Power Delivery Bus Protection | Industrial Load Switch Input Protection |
|---|---|
Use Scenario: Protecting 20V–22V USB PD VBus lines from lightning-induced surges and connector ESD events in notebooks and docking stations. IC Role / Device Role / Timing Role: Primary EOS shunt suppressor placed directly at Type-C connector, clamping transients before they reach PD controller or load switch. Use Value: Maintains 27.5–28V clamping at 40A and 125°C-prevents overvoltage damage to 22V-rated PD controllers where standard TVS would exceed 35V. |
Use Scenario: Safeguarding enable and input pins of industrial-grade load switches (e.g., HS2950P) against EOS in remote meters and robotics. IC Role / Device Role / Timing Role: Front-end transient diverter that limits voltage seen by the load switch's internal FET gate and drain. Use Value: Keeps clamping voltage below the 30V+ absolute maximum rating of common load switches-avoiding latch-up or permanent failure during 1kV/42Ω surges. |
| IoT Device Power Rail Protection | Storage Device 22V Supply Protection |
Use Scenario: Securing 22V auxiliary power rails in battery-powered IoT gateways exposed to field ESD and induced surges. IC Role / Device Role / Timing Role: Single-device solution for high-energy EOS suppression on compact PCBs with limited space for discrete TVS arrays. Use Value: 1.6mm × 1.6mm DFN footprint saves >60% board area vs. equivalent SOD-123 or SMA TVS solutions while delivering superior clamping. |
Use Scenario: Protecting 22V DC input of NVMe SSD enclosures and enterprise storage backplanes from hot-plug transients and system-level surges. IC Role / Device Role / Timing Role: High-reliability bus protector placed at power entry point, rated for repeated 40A surge events without degradation. Use Value: 1120W peak pulse power rating and −55°C to +150°C junction temperature range ensure long-term reliability in thermally demanding storage chassis. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ22A | Standard unidirectional TVS diode; 35.1V clamping at 12.3A (8/20μs), higher RDYN (~0.5Ω), VBR = 24.4–26.9V | Limited to lower-energy surges; clamping rises to >40V at 40A and 125°C-unsuitable for 22V-tolerant ICs | Select only if cost sensitivity outweighs clamping performance and temperature stability requirements |
| TDS2211P | Same die, identical electrical specs and DFN-6 package; Semtech's official part number for this device | Direct functional and mechanical replacement; same marking (T22), tape/reel, and qualification | Preferred for new designs-1N6638 is legacy designation; TDS2211P is current production part with full documentation support |
Compared with SMAJ22A, 1N6638 delivers 12V lower clamping at 40A and stable performance across temperature-critical for 22V systems-while TDS2211P is its exact form-fit-function replacement with updated manufacturing traceability and datasheet alignment.
Availability
1N6638 is available at Aetrix Electronics and suitable for USB Type-C power delivery, industrial load switch protection, and IoT device 22V rail applications requiring stable component supply, long-term lifecycle assurance, and consistent surge performance.
Supply support for 1N6638 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 analog and mixed-signal ICs for precision sensing, protection, and signal integrity.
The 1N6638 belongs to Semtech's Transient Diverting Suppressor (TDS) product line-engineered to replace conventional TVS diodes in high-reliability 20–30V power rail protection where flat clamping and temperature stability are mandatory.
FAQ
What is the clamping voltage of the 1N6638 at 40A surge current?
The 1N6638 clamps at 27.5–28V under 40A peak pulse current (8/20μs waveform), as guaranteed by design and validated across −40°C to +125°C. This stable clamping-unlike conventional TVS diodes-is enabled by its FET-based shunt architecture and 20mΩ dynamic resistance, ensuring protected downstream ICs remain within safe 22V-tolerant operating limits.
Is the 1N6638 pin-compatible with standard TVS diodes in SOD-123 or SMA packages?
No-the 1N6638 uses a 6-pin DFN-1616 package (1.6mm × 1.6mm) with three parallel input pins (4,5,6) and three parallel ground pins (1,2,3); it is not pin-compatible with 2-pin SOD-123 or SMA TVS diodes. Its layout requires dedicated land pattern per Semtech's recommended footprint, with multi-via grounding for optimal surge current handling.
Does the 1N6638 require a thermal pad or heatsink for 40A surge operation?
No-the 1N6638 dissipates surge energy in its silicon FET structure, not at a junction like traditional TVS diodes, so no thermal pad or external heatsink is required. Semtech explicitly states "no thermal pad is needed" in the datasheet; PCB layout focuses on low-inductance grounding via multiple vias to pins 1–3 instead.
Can the 1N6638 protect high-speed data lines like USB SuperSpeed or PCIe?
No-the 1N6638 is intended for power or low-speed I/O line protection (e.g., USB PD VBus, CC, SBU, load switch inputs), not high-speed signal lines. Its 175pF junction capacitance would severely degrade signal integrity on >1Gbps interfaces; Semtech recommends RClamp3371ZC (<0.25pF) for SuperSpeed lanes alongside 1N6638 for VBus.
What is the difference between 1N6638 and TDS2211P?
The 1N6638 and TDS2211P are identical devices-same silicon die, electrical specifications, DFN-6 package, marking code (T22), and qualification. TDS2211P is Semtech's current official part number; 1N6638 is a legacy designation still used in some distributor catalogs. For new designs, TDS2211P is recommended due to active documentation and supply chain support.
1N6638 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):
- 125 V
- Current - Average Rectified (Io):
- 300mA
- Voltage - Forward (Vf) (Max) @ If:
- 800 mV @ 10 mA
- Speed:
- Fast Recovery =< 500ns, > 200mA (Io)
- Reverse Recovery Time (trr):
- 4.5 ns
- Current - Reverse Leakage @ Vr:
- 500 nA @ 125 V
- Capacitance @ Vr, F:
- -
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- Axial
- Operating Temperature - Junction:
- -
1N6638 FAQ
1.How can I place an order for 1N6638 through Aetrix?
Please submit a Request for Quotation (RFQ) for 1N6638 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 1N6638 reliable?
The price and inventory of 1N6638 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1N6638 is usually 5 days.
3.What payment methods are accepted for 1N6638?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1N6638 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1N6638?
1N6638 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1N6638 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 1N6638?
For technical support, including 1N6638 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1N6638 requirements.
6.How does Aetrix verify that 1N6638 is sourced from the original manufacturer or authorized distributors?
All 1N6638 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 1N6638 meets industry standards.
7.What is the process for return or replacement of 1N6638?
All 1N6638 units undergo pre-shipment inspection (PSI). If there is an issue with 1N6638, 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 1N6638 part is unused and in its original packaging.
Return procedure for 1N6638:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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