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Vishay General Semiconductor - Diodes Division SMAJ18AHM3/I
- Part No.:
- SMAJ18AHM3/I
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ18AHM3/I.pdf
- Description:
- TVS DIODE 18VWM 29.2VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:7,861
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Product details
Overview
SMAJ18AHM3/I 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 (10/1000 μs waveform), targeting protection of MOSFETs, ICs, and sensor interfaces in automotive and industrial systems.
For engineers reviewing the SMAJ18AHM3/I datasheet, SMAJ18AHM3/I pinout, SMAJ18AHM3/I application, or SMAJ18AHM3/I equivalent, key selection criteria include its AEC-Q101 qualification (HM3 suffix), halogen-free RoHS compliance, 150 °C max junction temperature, low incremental surge resistance, and suitability for inductive load switching and ESD-prone signal line protection.
Technical Context
The SMAJ18AHM3/I operates as a unidirectional avalanche diode with glass-passivated junction, responding to fast transients (<1 ps intrinsic response) by entering breakdown when reverse voltage exceeds VBR. Its clamping action limits downstream voltage to ≤29.2 V under 13.7 A surge, maintaining circuit integrity during 10/1000 μs lightning-induced surges.
Thermally, it exhibits RθJA = 120 °C/W and RθJL = 30 °C/W, requiring minimum 0.2" × 0.2" copper pads per terminal for rated 400 W pulse handling. The cathode band denotes polarity, and it meets MSL Level 1 (260 °C reflow peak) per J-STD-020.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 18 V - Maximum continuous reverse operating voltage before leakage exceeds 1 μA; defines safe DC bias margin. |
| VBR min/max | 20.0 V / 22.1 V at 1 mA - Confirmed breakdown range ensures reliable turn-on within spec across production lot. |
| VC @ IPPM | 29.2 V at 13.7 A - Clamped voltage during 10/1000 μs surge; determines protected circuit's maximum stress level. |
| PPPM | 400 W - Peak pulse power handling capability; enables robust protection against IEC 61000-4-5 Level 4 surges. |
| ID @ VWM | 1.0 μA - Reverse leakage at stand-off voltage; low value minimizes standby power loss in battery-powered systems. |
| TJ max | +150 °C - Maximum junction temperature; supports operation in under-hood automotive environments. |
| Package | SMA (DO-214AC) - Surface-mount outline with 5.28 mm length, 4.50 mm width, and 2.29 mm height; compatible with automated pick-and-place. |
Pinout & Package
Package: SMA (DO-214AC), molded epoxy case with matte tin-plated leads, UL 94 V-0 rated, MSL Level 1 compliant. Cathode indicated by band; anode is unmarked end.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Cathode (banded end) | Reverse-biased terminal | Connected to protected line; conducts during overvoltage to shunt surge current to ground. |
| Anode (unbanded end) | Reference/ground terminal | Typically tied to system ground or low-impedance return path; completes clamping loop during transient event. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified (HM3 suffix) | Validated for automotive-grade reliability including temperature cycling, HTRB, and ESD testing per AEC standard. |
| Halogen-free & RoHS-compliant | Meets environmental compliance requirements for modern automotive and industrial PCB assemblies without compromising thermal performance. |
| 400 W peak pulse power (10/1000 μs) | Supports IEC 61000-4-5 surge immunity up to 4 kV (line-to-ground) in properly laid-out designs with adequate copper area. |
| Low clamping ratio (VC/VBR ≈ 1.39) | Minimizes overvoltage overshoot during clamping, reducing stress on downstream MOSFET gates and IC inputs. |
| Fast response time (<1 ps) | Activates before most semiconductor damage thresholds are exceeded, enabling protection of high-speed logic and analog front-ends. |
Applications
| Automotive Power Rail Protection | Industrial Sensor Signal Line Protection |
|---|---|
Use Scenario: Protecting 12 V battery-fed ECUs from load dump and alternator transients. IC Role / Device Role / Timing Role: Unidirectional TVS placed between power rail and chassis ground to clamp spikes above 29.2 V. Use Value: Prevents latch-up or gate oxide rupture in microcontrollers and power management ICs during ISO 7637-2 Pulse 5a events. | Use Scenario: Shielding analog output lines (e.g., 4–20 mA current loops) from ESD and cable discharge events. IC Role / Device Role / Timing Role: TVS mounted at connector interface to divert sub-100 ns ESD pulses away from precision op-amps and ADC drivers. Use Value: Maintains signal integrity and avoids calibration drift caused by transient-induced offset shifts in sensor conditioning circuits. |
| Consumer Device USB Port Protection | MOSFET Gate Drive Circuit Protection |
Use Scenario: Safeguarding USB 2.0 data lines (D+/D−) against human-body-model (HBM) ESD up to ±15 kV. IC Role / Device Role / Timing Role: Bidirectional-capable variant not used here; SMAJ18AHM3/I applied on VBUS line only due to unidirectional rating. Use Value: Limits VBUS overvoltage to ≤29.2 V during hot-plug surges, preventing damage to USB controller power domains. | Use Scenario: Clamping Miller-induced voltage spikes on high-side N-channel MOSFET gates driven by PWM controllers. IC Role / Device Role / Timing Role: Connected between gate and source to clamp dv/dt-induced ringing exceeding 18 V. Use Value: Avoids false turn-on and shoot-through in half-bridge configurations by limiting gate-source voltage excursion. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ18AHE3/I | Same electrical specs but RoHS-compliant (not halogen-free); lacks AEC-Q101 qualification. | Restricted to commercial-grade industrial or consumer use; not approved for automotive under-hood deployment. | Select when halogen-free content is not mandated and automotive qualification is unnecessary. |
| SMBJ18A-HM3/I | Same VWM/VBR/VC ratings but in larger SMB (DO-214AA) package; higher thermal mass (RθJA = 80 °C/W). | Better suited for higher average power dissipation or less aggressive board layout; requires more PCB area. | Choose when improved thermal derating or legacy SMB footprint compatibility is prioritized over miniaturization. |
Compared with SMAJ18AHM3/I, SMAJ18AHE3/I offers identical clamping performance without halogen-free assurance or automotive qualification, while SMBJ18A-HM3/I delivers equivalent protection in a thermally superior but physically larger package-enabling trade-offs between board space, thermal margin, and compliance scope.
Availability
SMAJ18AHM3/I is available at Aetrix Electronics and suitable for automotive electronics, industrial sensor interfaces, and consumer power supply protection requiring stable component supply, long-term lifecycle support, and AEC-Q101 traceability.
Supply support for SMAJ18AHM3/I 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, efficiency, and application-specific optimization.
The SMAJ series was developed for high-reliability transient suppression in space-constrained, high-surge environments-including automotive power distribution, industrial automation I/O modules, and telecom infrastructure-leveraging TRANSZORB® technology for consistent clamping.
FAQ
What is the maximum clamping voltage of the SMAJ18AHM3/I under a 10/1000 μs surge?
The SMAJ18AHM3/I has a maximum clamping voltage (VC) of 29.2 V at 13.7 A peak pulse current (IPPM) under a 10/1000 μs waveform. This value is measured per JEDEC standards and guarantees that downstream components experience no more than 29.2 V during such transient events, making SMAJ18AHM3/I suitable for protecting 24 V nominal systems where overvoltage headroom is tightly constrained.
Is the SMAJ18AHM3/I qualified for automotive applications?
Yes, the SMAJ18AHM3/I carries the HM3 suffix, indicating it is halogen-free, RoHS-compliant, and AEC-Q101 qualified. This certification covers stress tests including high-temperature reverse bias, temperature cycling, and ESD, confirming its suitability for under-hood and body-control module applications where reliability under thermal and mechanical stress is critical-distinct from non-qualified variants like SMAJ18A-E3/I.
What does the "HM3" suffix mean in SMAJ18AHM3/I?
The "HM3" suffix in SMAJ18AHM3/I denotes halogen-free, RoHS-compliant construction with AEC-Q101 qualification. It differentiates this part from commercial-grade versions (E3/M3) and confirms compliance with automotive environmental and reliability standards, including whisker resistance (JESD 201 Class 2) and moisture sensitivity level (MSL Level 1, 260 °C peak reflow). This makes SMAJ18AHM3/I appropriate for Tier 1 automotive supply chains requiring full material and process traceability.
Can SMAJ18AHM3/I be used for bidirectional transient suppression?
No, SMAJ18AHM3/I is a unidirectional TVS diode, as indicated by the "A" (not "CA") suffix and the presence of a cathode band. It conducts only in reverse bias and must be oriented with the banded end toward the protected line. For bidirectional protection-such as AC signal lines or differential buses-SMAJ18CA variants (e.g., SMAJ18CAHM3/I) are required, which exhibit symmetrical clamping in both polarities and lack polarity marking.
What is the thermal resistance junction-to-ambient (RθJA) for SMAJ18AHM3/I?
The SMAJ18AHM3/I has a typical thermal resistance junction-to-ambient (RθJA) of 120 °C/W when mounted on the minimum recommended pad layout (0.2" × 0.2" copper per terminal). This value assumes natural convection and defines the temperature rise per watt of sustained power dissipation; for pulsed operation, thermal inertia allows brief 400 W surges without exceeding the +150 °C maximum junction temperature, provided PCB layout adheres to Vishay's mounting guidelines.
SMAJ18AHM3/I 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/I FAQ
1.How can I place an order for SMAJ18AHM3/I through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ18AHM3/I 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/I reliable?
The price and inventory of SMAJ18AHM3/I are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ18AHM3/I is usually 5 days.
3.What payment methods are accepted for SMAJ18AHM3/I?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ18AHM3/I transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ18AHM3/I?
SMAJ18AHM3/I orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ18AHM3/I 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/I?
For technical support, including SMAJ18AHM3/I datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ18AHM3/I requirements.
6.How does Aetrix verify that SMAJ18AHM3/I is sourced from the original manufacturer or authorized distributors?
All SMAJ18AHM3/I 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/I meets industry standards.
7.What is the process for return or replacement of SMAJ18AHM3/I?
All SMAJ18AHM3/I units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ18AHM3/I, 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/I part is unused and in its original packaging.
Return procedure for SMAJ18AHM3/I:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMAJ18AHM3/I Tags
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