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Vishay General Semiconductor - Diodes Division SMAJ20AHM3/I
- Part No.:
- SMAJ20AHM3/I
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ20AHM3/I.pdf
- Description:
- TVS DIODE 20VWM 32.4VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:2,811
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Product details
Overview
SMAJ20AHM3/I from Vishay General Semiconductor is a unidirectional surface-mount Transient Voltage Suppressor (TVS) diode designed for robust overvoltage protection of sensitive electronics. It features a 20 V stand-off voltage (VWM), 22.2–24.5 V breakdown voltage (VBR) at 1 mA, 32.4 V maximum clamping voltage (VC) at 12.3 A peak pulse current (IPPM), and 400 W peak pulse power rating with 10/1000 μs waveform - deployed on signal lines and power rails in automotive ECUs and industrial sensor interfaces.
For engineers reviewing the SMAJ20AHM3/I datasheet, SMAJ20AHM3/I pinout, SMAJ20AHM3/I application, or SMAJ20AHM3/I equivalent, this part serves as a halogen-free, AEC-Q101-qualified TVS for high-reliability 24 V system protection where low clamping voltage, fast response (<1 ns), and MSL Level 1 moisture sensitivity are critical selection criteria.
Technical Context
The SMAJ20AHM3/I operates as a unidirectional avalanche diode, conducting only when reverse voltage exceeds its breakdown threshold to shunt transient energy to ground. Its glass-passivated junction ensures stable VBR tolerance and low leakage (<1 μA at 20 V), while the SMA (DO-214AC) package enables automated placement and meets UL 94 V-0 flammability requirements.
Designed for repetitive surge suppression under 0.01% duty cycle, it delivers 400 W peak pulse power up to 78 V and derates to 300 W above that - validated with 8.3 ms half-sine IFSM = 40 A surge capability and thermal resistance RθJA = 120 °C/W on standard 5.0 mm × 5.0 mm copper pads.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM (Stand-off Voltage) | 20 V - maximum continuous reverse operating voltage before clamping begins; defines safe operating margin for 24 V nominal systems. |
| VBR (Breakdown Voltage) | 22.2–24.5 V at 1 mA - tight tolerance ensures predictable turn-on during transients without false triggering. |
| VC (Clamping Voltage) | 32.4 V at IPPM = 12.3 A - limits downstream voltage stress during 10/1000 μs surges, protecting 3.3 V/5 V logic and MOSFET gates. |
| PPPM (Peak Pulse Power) | 400 W (10/1000 μs) - sustains high-energy lightning-induced or inductive-switching transients without failure. |
| ID (Reverse Leakage) | <1 μA at 20 V - negligible standby current preserves battery life and avoids signal integrity issues in low-power sensor nodes. |
| TJ max. | +150 °C - supports operation in under-hood automotive environments and industrial enclosures without derating. |
| Package | SMA (DO-214AC) - industry-standard surface-mount outline with cathode band marking; compatible with reflow and wave soldering per J-STD-002. |
Pinout & Package
Package: SMA (DO-214AC), molded plastic case with matte tin-plated leads; polarity indicated by cathode band on unidirectional devices.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction terminal | Connected to protected line (e.g., 24 V rail or signal input); conducts during forward-biased ESD events. |
| Cathode | Reverse-biased clamping terminal | Connected to ground reference; avalanches at VBR to clamp transients and divert surge current away from ICs. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive applications including engine control, body electronics, and ADAS sensors per stress test requirements. |
| Halogen-free & RoHS-compliant | HM3 suffix denotes compliance with JEDEC J-STD-201 Class 2 whisker resistance and environmental regulations for green manufacturing. |
| 400 W peak pulse power | Handles ISO 7637-2 Pulse 1/2a/5a transients and IEC 61000-4-5 Level 4 surges without degradation in 24 V systems. |
| Low clamping ratio (VC/VBR ≈ 1.4) | Minimizes overvoltage overshoot during clamping - critical for safeguarding gate oxides of MOSFETs and input stages of CAN transceivers. |
| MSL Level 1 (260 °C peak) | Enables single-reflow assembly without baking; eliminates moisture-related popcorning risk in high-volume SMT production. |
Applications
| Automotive Body Control Module (BCM) | Industrial PLC Digital Input Card |
|---|---|
|
Use Scenario: Protects microcontroller GPIOs and LIN bus transceivers from load dump and alternator ripple in vehicle door modules. IC Role / Device Role / Timing Role: Unidirectional TVS placed between LIN line and chassis ground to clamp negative transients below -40 V and positive spikes above 20 V. Use Value: Prevents latch-up and permanent damage to 5 V tolerant transceivers during 12 V system load dump events (ISO 16750-2). |
Use Scenario: Shields 24 V DC digital input circuits from inductive kickback when solenoids or relays de-energize. IC Role / Device Role / Timing Role: Standoff-rated TVS connected across input terminals to absorb 600 W+ switching surges before reaching optocoupler or MCU input stage. Use Value: Enables reliable 100 k-cycle operation of PLC inputs without field failures due to repeated 10/1000 μs transients. |
| Telecom Power Supply Front-End | Consumer Appliance Motor Driver Board |
|
Use Scenario: Guards AC/DC adapter secondary-side 24 V output against lightning-induced surges entering via Ethernet or PoE lines. IC Role / Device Role / Timing Role: Primary-level TVS on DC output rail, coordinated with upstream MOV and downstream LC filtering to meet IEC 61000-4-5 Level 3. Use Value: Reduces need for oversized capacitors and extends lifetime of DC-DC converters by limiting voltage excursion to ≤32.4 V. |
Use Scenario: Safeguards H-bridge gate drivers in washing machine motor controllers from back-EMF spikes during PWM commutation. IC Role / Device Role / Timing Role: Localized TVS on each half-bridge supply rail (VDD and VSS) to clamp fast-rising <100 ns transients induced by MOSFET switching. Use Value: Eliminates gate oxide breakdown in 600 V MOSFETs by clamping transients within 1 ns response time and sub-33 V VC. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ20AHE3/I | Same electrical specs but RoHS-compliant (non-halogen-free) and commercial-grade; lacks AEC-Q101 qualification. | Suitable for non-automotive industrial or consumer use where halogen content is unrestricted and automotive qualification is unnecessary. | Select SMAJ20AHE3/I for cost-sensitive commercial designs without automotive reliability requirements. |
| SMBJ20A-HM3 | Higher 600 W PPPM rating, SMB (DO-214AA) package - larger footprint and 20% higher clamping voltage (34.4 V). | Better suited for higher-energy transients but requires PCB layout change; not drop-in compatible due to different pad dimensions. | Choose SMBJ20A-HM3 only when 400 W is insufficient and board space allows larger SMB footprint. |
Compared with SMAJ20AHM3/I, SMAJ20AHE3/I offers identical protection performance without halogen-free assurance or automotive qualification, while SMBJ20A-HM3 provides greater surge capacity at the expense of board area and tighter clamping - making SMAJ20AHM3/I optimal for space-constrained AEC-Q101-compliant 24 V systems.
Availability
SMAJ20AHM3/I is available at Aetrix Electronics and suitable for automotive body electronics, industrial PLC input protection, telecom power front-ends, and appliance motor control requiring stable component supply with full traceability and long-term lifecycle support.
Supply support for SMAJ20AHM3/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, MOSFETs, and protection devices with emphasis on reliability, efficiency, and application-specific optimization.
The SMAJ series targets high-reliability transient suppression in automotive, industrial, and telecom infrastructure - engineered for fast clamping, low leakage, and robust surge handling in harsh environments.
FAQ
What is the clamping voltage of the SMAJ20AHM3/I at its rated peak pulse current?
The SMAJ20AHM3/I has a maximum clamping voltage (VC) of 32.4 V at its peak pulse current (IPPM) of 12.3 A, measured under the standardized 10/1000 μs waveform. This value ensures downstream components like 3.3 V microcontrollers or 5 V transceivers remain within safe voltage limits during surge events. The SMAJ20AHM3/I achieves this with a low clamping ratio of approximately 1.4, reflecting efficient avalanche conduction without excessive overshoot.
Is the SMAJ20AHM3/I suitable for automotive applications?
Yes, the SMAJ20AHM3/I is AEC-Q101 qualified, meaning it has passed rigorous stress tests for temperature cycling, humidity, mechanical shock, and surge endurance required for automotive electronic systems. Its HM3 suffix confirms halogen-free, RoHS-compliant construction and JESD201 Class 2 whisker resistance - making SMAJ20AHM3/I appropriate for under-hood and cabin modules including BCMs, lighting controls, and sensor interfaces.
How does the SMAJ20AHM3/I differ from the SMAJ20A-E3/61 variant?
The SMAJ20AHM3/I differs from SMAJ20A-E3/61 primarily in material composition and qualification: HM3 denotes halogen-free and AEC-Q101 qualification, whereas E3 indicates RoHS-compliant but non-halogen-free commercial grade. Both share identical electrical parameters (VWM = 20 V, VC = 32.4 V), but SMAJ20AHM3/I is certified for automotive use and manufactured to stricter material standards - critical for Tier 1 suppliers requiring full compliance documentation.
What is the thermal resistance of the SMAJ20AHM3/I, and how does it affect PCB layout?
The SMAJ20AHM3/I has a typical junction-to-ambient thermal resistance (RθJA) of 120 °C/W when mounted on 0.2" × 0.2" (5.0 mm × 5.0 mm) copper pads per terminal. This value assumes minimal copper area; increasing pad size or adding thermal vias reduces RθJA and improves surge survivability. For sustained power dissipation or high ambient temperatures, designers should verify junction temperature using PD = 3.3 W and ensure TJ stays below +150 °C - especially in sealed automotive enclosures.
Can the SMAJ20AHM3/I be used in bidirectional protection circuits?
No, the SMAJ20AHM3/I is a unidirectional TVS diode, identifiable by its cathode band marking and specified breakdown behavior only in reverse bias. For bidirectional protection - such as AC signal lines or differential buses - a CA-suffixed part like SMAJ20CA must be used. Attempting to use SMAJ20AHM3/I in bidirectional configurations risks forward conduction during negative transients and inadequate clamping, compromising system reliability.
SMAJ20AHM3/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):
- 20V
- Voltage - Breakdown (Min):
- 22.2V
- Voltage - Clamping (Max) @ Ipp:
- 32.4V
- Current - Peak Pulse (10/1000µs):
- 12.3A
- 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)
SMAJ20AHM3/I FAQ
1.How can I place an order for SMAJ20AHM3/I through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ20AHM3/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 SMAJ20AHM3/I reliable?
The price and inventory of SMAJ20AHM3/I are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ20AHM3/I is usually 5 days.
3.What payment methods are accepted for SMAJ20AHM3/I?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ20AHM3/I transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ20AHM3/I?
SMAJ20AHM3/I orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ20AHM3/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 SMAJ20AHM3/I?
For technical support, including SMAJ20AHM3/I datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ20AHM3/I requirements.
6.How does Aetrix verify that SMAJ20AHM3/I is sourced from the original manufacturer or authorized distributors?
All SMAJ20AHM3/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 SMAJ20AHM3/I meets industry standards.
7.What is the process for return or replacement of SMAJ20AHM3/I?
All SMAJ20AHM3/I units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ20AHM3/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 SMAJ20AHM3/I part is unused and in its original packaging.
Return procedure for SMAJ20AHM3/I:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMAJ20AHM3/I Tags
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