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Vishay General Semiconductor - Diodes Division SMAJ18AHM3/H
- Part No.:
- SMAJ18AHM3/H
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ18AHM3/H.pdf
- Description:
- TVS DIODE 18VWM 29.2VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:4,654
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Product details
Overview
SMAJ18AHM3/H from Vishay General Semiconductor is a unidirectional surface-mount Transient Voltage Suppressor (TVS) diode in SMA (DO-214AC) package, designed for clamping voltage transients on power and signal lines. It features a 18 V stand-off voltage (VWM), 20.0–22.1 V breakdown voltage (VBR) at 1 mA, 29.2 V maximum clamping voltage (VC) at 13.7 A peak pulse current (IPPM), and 400 W peak pulse power rating with 10/1000 μs waveform - used to protect MOSFETs, ICs, and sensor interfaces in automotive and industrial control systems.
For engineers reviewing the SMAJ18AHM3/H datasheet, SMAJ18AHM3/H pinout, SMAJ18AHM3/H application, or SMAJ18AHM3/H equivalent, key selection criteria include unidirectional polarity, AEC-Q101 qualification status, 120 °C/W junction-to-ambient thermal resistance, and compatibility with automated SMT placement on 0.2" × 0.2" copper pads.
Technical Context
This TVS diode operates as a clamping device in reverse-biased configuration, conducting only when transient voltage exceeds its breakdown threshold. Its glass-passivated junction ensures stable leakage performance (<1.0 μA at VWM), while low incremental surge resistance enables rapid energy diversion during ESD or inductive switching events.
The SMAJ18AHM3/H is halogen-free, RoHS-compliant, and qualified to AEC-Q101 for automotive use. It meets MSL Level 1 per J-STD-020 with 260 °C reflow peak temperature tolerance and supports repetitive surge duty cycles up to 0.01 % at 400 W (derated to 300 W above 78 V).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 18 V - maximum continuous reverse operating voltage before clamping begins |
| VBR min/max | 20.0 V / 22.1 V at 1 mA - defines reliable turn-on window under standardized test conditions |
| VC @ IPPM | 29.2 V at 13.7 A - clamped voltage seen by protected circuit during worst-case 10/1000 μs surge |
| PPPM | 400 W - peak transient power it can absorb without failure (10/1000 μs waveform) |
| ID @ VWM | ≤1.0 μA - ultra-low reverse leakage preserves signal integrity and system quiescent current |
| TJ max | +150 °C - maximum junction temperature enabling operation in under-hood automotive environments |
| RθJA | 120 °C/W - thermal resistance indicating required PCB copper area for safe power dissipation |
Pinout & Package
Package: SMA (DO-214AC), surface-mount, single-ended cathode-marked case with matte tin-plated leads solderable per J-STD-002 and JESD 22-B102. Polarity indicated by black band denoting cathode terminal.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Cathode (banded end) | Anode of internal PN junction | Connected to protected line; conducts surge current toward ground when transient exceeds VBR |
| Anode (unmarked end) | Cathode of internal PN junction | Typically tied to system ground or low-impedance return path for effective clamping |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive applications including engine control units and body electronics |
| Halogen-free & RoHS-compliant | Meets environmental compliance requirements for global automotive and industrial markets |
| 400 W peak pulse power | Handles high-energy transients from inductive load switching (e.g., solenoids, relays) |
| Fast response time & low clamping ratio | Clamps within picoseconds with VC/VBR ≈ 1.46 - minimizing overvoltage stress on downstream ICs |
| MSL Level 1 moisture sensitivity | Allows unlimited floor life and standard reflow without baking preconditioning |
Applications
| Automotive Power Line Protection | Industrial Sensor Interface Protection |
|---|---|
Use Scenario: Protecting 12 V battery-fed ECUs against load dump and alternator ripple transients. IC Role / Device Role / Timing Role: Unidirectional TVS placed between power rail and chassis ground to clamp surges above 22.1 V. Use Value: Prevents latch-up or permanent damage to microcontrollers and CAN transceivers during ISO 7637-2 Pulse 5a events. | Use Scenario: Safeguarding analog output lines of pressure or temperature sensors in PLC I/O modules. IC Role / Device Role / Timing Role: Clamping device on 4–20 mA loop or 0–10 V signal path against ESD and field wiring faults. Use Value: Maintains measurement accuracy by limiting transient-induced offset errors and preventing ADC saturation. |
| Consumer Device USB Port Protection | Telecom Base Station DC Power Input |
Use Scenario: Adding secondary surge protection on VBUS line of USB 2.0 host ports in set-top boxes or smart displays. IC Role / Device Role / Timing Role: Standoff-rated TVS placed upstream of USB power switch to suppress contact discharge ESD. Use Value: Complies with IEC 61000-4-2 Level 4 (±15 kV air/±8 kV contact) without affecting USB enumeration timing. | Use Scenario: Front-end transient suppression on -48 V DC input of telecom remote radio heads. IC Role / Device Role / Timing Role: Unidirectional clamping device referenced to negative rail to handle negative-going surges. Use Value: Withstands repeated 10/1000 μs surges up to 400 W while maintaining <1 μA leakage at nominal -48 V operation. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ18AHE3/H | Same electrical specs; RoHS-compliant but not halogen-free | Lacks halogen-free certification required for some Tier 1 automotive programs | Select SMAJ18AHM3/H when halogen-free compliance is mandated by OEM specification |
| SMBJ18A-H | Higher 600 W PPPM rating; SMB (DO-214AA) package with larger footprint and lower RθJA (85 °C/W) | Better thermal performance but requires PCB layout change and higher assembly cost | Choose SMBJ18A-H only if system-level testing confirms need for >400 W surge handling or improved thermal margin |
Compared with SMAJ18AHE3/H and SMBJ18A-H, the SMAJ18AHM3/H uniquely combines AEC-Q101 qualification, halogen-free construction, and SMA footprint - making it optimal for space-constrained automotive modules where material compliance and reliability validation are jointly required.
Availability
SMAJ18AHM3/H is available at Aetrix Electronics and suitable for automotive electronic control units, industrial sensor interfaces, and telecom power supply inputs requiring stable component supply across long production lifecycles.
Supply support for SMAJ18AHM3/H 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 General Semiconductor is a global leader in discrete semiconductors, specializing in diodes, rectifiers, TVS devices, and optoelectronics with emphasis on reliability and application-specific performance.
The SMAJ series was developed specifically for robust, surface-mount transient suppression in harsh environments - targeting automotive, industrial, and telecom applications where AEC-Q101 qualification and consistent clamping behavior are mandatory.
FAQ
What does the "HM3" suffix indicate in SMAJ18AHM3/H?
The "HM3" suffix in SMAJ18AHM3/H denotes halogen-free, RoHS-compliant construction with AEC-Q101 qualification. The "H" indicates automotive-grade qualification, "M3" specifies halogen-free materials, and the trailing "/H" refers to the packaging variant (7″ tape-and-reel, 1800 units per reel). This distinguishes it from commercial-grade "E3" or non-halogen-free "HE3" variants.
Is SMAJ18AHM3/H bidirectional or unidirectional?
SMAJ18AHM3/H is a unidirectional TVS diode, confirmed by its part number ending in "A" (not "CA") and explicit marking as unidirectional in Vishay's datasheet Table 1. It conducts only in reverse bias - the cathode band must be oriented toward the protected line, with anode connected to ground for proper clamping operation.
What is the maximum clamping voltage of SMAJ18AHM3/H at rated surge current?
The maximum clamping voltage (VC) of SMAJ18AHM3/H is 29.2 V at 13.7 A peak pulse current (IPPM), measured under standardized 10/1000 μs waveform conditions. This value ensures protected circuits experience no more than 29.2 V during worst-case transient events, providing design margin below typical 3.3 V or 5 V IC absolute maximum ratings.
Can SMAJ18AHM3/H replace SMAJ18A-E3 in an existing design?
SMAJ18AHM3/H can replace SMAJ18A-E3 electrically and mechanically, as both share identical SMA (DO-214AC) package, pinout, and core electrical parameters. However, SMAJ18AHM3/H adds halogen-free and AEC-Q101 qualifications - so replacement is acceptable if those certifications are not already required; otherwise, full requalification may be needed for automotive deployment.
What is the thermal resistance and how does it affect PCB layout for SMAJ18AHM3/H?
SMAJ18AHM3/H has a typical junction-to-ambient thermal resistance (RθJA) of 120 °C/W when mounted on minimum recommended 0.2" × 0.2" (5.0 mm × 5.0 mm) copper pads per terminal. To maintain TJ ≤ 150 °C under 400 W surge, adequate copper area and thermal vias are essential - undersized pads risk localized overheating and premature failure during repetitive transients.
SMAJ18AHM3/H Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Package/Case:
- DO-214AC, SMA
- Series:
- TransZorb®
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Discontinued at Digi-Key
- Type:
- Zener
- Unidirectional Channels:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 18V
- Voltage - Breakdown (Min):
- 20V
- Voltage - Clamping (Max) @ Ipp:
- 29.2V
- Current - Peak Pulse (10/1000µs):
- 13.7A
- Power - Peak Pulse:
- 400W
- Power Line Protection:
- No
- Applications:
- Telecom
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 150°C (TJ)
- Grade:
- Automotive
- Qualification:
- AEC-Q101
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-214AC (SMA)
SMAJ18AHM3/H FAQ
1.How can I place an order for SMAJ18AHM3/H through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ18AHM3/H 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 SMAJ18AHM3/H reliable?
The price and inventory of SMAJ18AHM3/H are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ18AHM3/H is usually 5 days.
3.What payment methods are accepted for SMAJ18AHM3/H?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ18AHM3/H transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ18AHM3/H?
SMAJ18AHM3/H orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ18AHM3/H 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 SMAJ18AHM3/H?
For technical support, including SMAJ18AHM3/H datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ18AHM3/H requirements.
6.How does Aetrix verify that SMAJ18AHM3/H is sourced from the original manufacturer or authorized distributors?
All SMAJ18AHM3/H 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 SMAJ18AHM3/H meets industry standards.
7.What is the process for return or replacement of SMAJ18AHM3/H?
All SMAJ18AHM3/H units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ18AHM3/H, 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 SMAJ18AHM3/H part is unused and in its original packaging.
Return procedure for SMAJ18AHM3/H:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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