Send an Inquiry

To receive a quote for your project, please fill in the following information, and we’ll get back to you promptly.

Submit Inventory List

Please fill in the following information, and we’ll get back to you promptly.

Home > Products > Circuit Protection > Transient Voltage Suppressors (TVS) > TVS Diodes

Vishay General Semiconductor - Diodes Division SMAJ18-E3/5A

Name: SMAJ18-E3/5A
Brand: Vishay General Semiconductor - Diodes Division
SKU: SMAJ18-E3/5A
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

Compare

Part No.:: SMAJ18-E3/5A

Manufacturer:: Vishay General Semiconductor - Diodes Division

Category:: TVS Diodes

Package:: DO-214AC, SMA

Datasheet:: SMAJ18-E3/5A.pdf

Description:: TVS DIODE 18VWM 32.2VC DO214AC

Quantity:: RFQ Add To RFQ list

Payment:

Shipping:

Inventory:3,193

Please send an inquiry. Send us your inquiry, and we will respond immediately.

Product details

Overview

SMAJ18-E3/5A from Vishay General Semiconductor is a unidirectional surface-mount Transient Voltage Suppressor (TVS) diode in DO-214AC (SMA) package, designed to protect sensitive electronics against voltage transients induced by inductive load switching and lightning. It features 18 V standoff voltage (V_WM), 32.2 V clamping voltage (V_C) at 12.4 A peak pulse current (I_PPM), and 400 W peak pulse power (10/1000 µs waveform).

For engineers reviewing the SMAJ18-E3/5A datasheet, SMAJ18-E3/5A pinout, SMAJ18-E3/5A application, or SMAJ18-E3/5A equivalent, this device is selected for robust ESD and surge protection in automotive sensor interfaces, industrial I/O lines, and DC power rail clamping where fast response (<1 ns), low clamping ratio, and RoHS-compliant commercial-grade reliability are required.

Technical Context

The SMAJ18-E3/5A operates as a unidirectional avalanche diode with cathode-band polarity marking, exhibiting a breakdown voltage (V_BR) of 20.0–24.4 V at 1 mA test current and maximum reverse leakage (I_D) ≤1.0 µA at 18 V standoff. Its thermal resistance is 120 °C/W (junction-to-ambient) on standard 0.2 × 0.2" copper pads.

It delivers 400 W peak pulse power up to 78 V and derates to 300 W above that threshold, with 40 A non-repetitive forward surge rating (8.3 ms half-sine) and 150 °C maximum junction temperature - enabling use in high-energy transient environments without thermal runaway under defined PCB layout conditions.

Key Specifications

Parameter	Value and Actual Design Meaning
V_WM	18 V - Maximum continuous reverse operating voltage before clamping begins; defines safe working range for protected circuit.
V_C @ I_PPM	32.2 V - Clamped voltage at 12.4 A peak pulse current; limits downstream voltage stress during surge events.
I_PPM	12.4 A - Peak surge current capability with 10/1000 µs waveform; determines energy-handling capacity per IEEE C62.35.
P_PPM	400 W - Peak pulse power dissipation; specifies transient energy absorption limit under standardized surge conditions.
T_J max.	+150 °C - Maximum junction temperature; sets thermal design margin for sustained operation and surge recovery.
R_θJA	120 °C/W - Junction-to-ambient thermal resistance on 0.2 × 0.2" copper pads; guides PCB copper area requirements for thermal management.

Pinout & Package

Package: DO-214AC (SMA), surface-mount, matte tin-plated leads, RoHS-compliant commercial grade (E3 suffix), MSL Level 1 (260 °C reflow).

Pin/Terminal	Circuit Role	Design Meaning
Anode	Forward conduction terminal	Connected to lower-potential side (e.g., ground or return path) in unidirectional configuration.
Cathode (marked with band)	Avalanche clamping terminal	Connected to protected line; conducts when reverse voltage exceeds V_WM, shunting surge to ground.

Key Features

Feature	Design Value
400 W peak pulse power (10/1000 µs)	Enables protection against high-energy transients such as ISO 7637-2 Pulse 1/2a/5a in automotive 12 V systems.
Clamping ratio (V_C/V_WM) = 1.79	Provides tight voltage limiting relative to standoff, minimizing overvoltage exposure to downstream ICs like MCUs or CAN transceivers.
Response time <1 ns	Ensures suppression before transient-induced damage occurs in fast-edge digital or analog signal paths.
MSL Level 1, 260 °C reflow compatible	Supports standard lead-free SMT assembly without pre-baking or special handling.

Applications

Automotive Sensor Protection	Industrial PLC I/O Protection
Use Scenario: Protecting analog output lines of engine coolant temperature sensors exposed to load dump and alternator ripple. IC Role / Device Role / Timing Role: Unidirectional TVS clamping transient spikes on 5 V or 12 V sensor supply rails before they reach ADC inputs or signal conditioning op-amps. Use Value: Prevents latch-up or parametric shift in precision sensor front-ends by limiting voltage to ≤32.2 V during 10/1000 µs surges up to 12.4 A.	Use Scenario: Shielding 24 V digital input modules in programmable logic controllers from inductive kickback of solenoid valves and contactors. IC Role / Device Role / Timing Role: Fast-acting surge shunt placed across input terminals to clamp transients before reaching optocoupler or Schmitt-trigger input stages. Use Value: Maintains functional safety integrity by ensuring input stage remains within absolute maximum ratings during repetitive 400 W surge events.
DC Power Rail Clamping	USB/Serial Interface ESD Protection
Use Scenario: Safeguarding 12 V or 24 V DC power distribution networks in embedded gateways against coupling from nearby motor drives. IC Role / Device Role / Timing Role: Parallel-connected TVS on main power bus to absorb energy from coupled transients before reaching DC-DC converters or PMICs. Use Value: Extends system uptime by preventing brownouts or reset events caused by transient-induced voltage sag or overvoltage on critical rails.	Use Scenario: Adding secondary-level surge immunity to RS-232 or USB VBUS lines in industrial field devices connected to noisy plant-floor cabling. IC Role / Device Role / Timing Role: Standoff-limited clamping element placed between connector and transceiver IC to suppress ESD (IEC 61000-4-2) and fast transients (IEC 61000-4-4). Use Value: Achieves Level 4 (±8 kV contact / ±15 kV air) ESD immunity without degrading signal integrity due to low 1.0 µA leakage at 18 V.

Automotive Sensor Protection

Industrial PLC I/O Protection

Use Scenario: Protecting analog output lines of engine coolant temperature sensors exposed to load dump and alternator ripple.

IC Role / Device Role / Timing Role: Unidirectional TVS clamping transient spikes on 5 V or 12 V sensor supply rails before they reach ADC inputs or signal conditioning op-amps.

Use Value: Prevents latch-up or parametric shift in precision sensor front-ends by limiting voltage to ≤32.2 V during 10/1000 µs surges up to 12.4 A.

Use Scenario: Shielding 24 V digital input modules in programmable logic controllers from inductive kickback of solenoid valves and contactors.

IC Role / Device Role / Timing Role: Fast-acting surge shunt placed across input terminals to clamp transients before reaching optocoupler or Schmitt-trigger input stages.

Use Value: Maintains functional safety integrity by ensuring input stage remains within absolute maximum ratings during repetitive 400 W surge events.

DC Power Rail Clamping

USB/Serial Interface ESD Protection

Use Scenario: Safeguarding 12 V or 24 V DC power distribution networks in embedded gateways against coupling from nearby motor drives.

IC Role / Device Role / Timing Role: Parallel-connected TVS on main power bus to absorb energy from coupled transients before reaching DC-DC converters or PMICs.

Use Value: Extends system uptime by preventing brownouts or reset events caused by transient-induced voltage sag or overvoltage on critical rails.

Use Scenario: Adding secondary-level surge immunity to RS-232 or USB VBUS lines in industrial field devices connected to noisy plant-floor cabling.

IC Role / Device Role / Timing Role: Standoff-limited clamping element placed between connector and transceiver IC to suppress ESD (IEC 61000-4-2) and fast transients (IEC 61000-4-4).

Use Value: Achieves Level 4 (±8 kV contact / ±15 kV air) ESD immunity without degrading signal integrity due to low 1.0 µA leakage at 18 V.

Equivalent & Alternatives

The following parts are listed as comparable options for similar transient voltage suppression applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
SMAJ18A-E3/5A	Lower V_BR (20.0–22.1 V vs. 20.0–24.4 V); tighter tolerance; 29.2 V clamping at 13.7 A.	Better suited for designs requiring tighter clamping voltage control and lower V_BR variation across temperature.	Select SMAJ18A-E3/5A when V_BR consistency and reduced clamping spread are prioritized over absolute peak power margin.
SMCJ18A-E3/57T	Higher power rating (1500 W), larger DO-214AB (SMC) package, same V_WM/V_C family, 15.4 A I_PPM.	Used where higher single-event energy absorption is needed, e.g., primary-level power input protection.	Choose SMCJ18A-E3/57T only if PCB space allows larger footprint and surge threat level exceeds 400 W capability.

Compared with SMAJ18-E3/5A, SMAJ18A-E3/5A offers improved V_BR consistency but identical package and layout; SMCJ18A-E3/57T provides 3.75× higher peak power in a larger package, requiring board redesign but enabling higher-threat environments.

Availability

SMAJ18-E3/5A is available at Aetrix Electronics and suitable for automotive sensor interfaces, industrial PLC I/O modules, and DC power rail clamping requiring stable component supply, full traceability, and long-term lifecycle support.

Supply support for SMAJ18-E3/5A 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 performance.

The SMAJ series is engineered for surface-mount transient suppression in automotive, industrial, and telecom systems - delivering consistent clamping, low leakage, and robust surge handling in compact DO-214AC packaging.

FAQ

What is the standoff voltage rating of the SMAJ18-E3/5A?

The SMAJ18-E3/5A has a standoff voltage (V_WM) of 18 V, meaning it remains non-conductive under normal operating conditions up to this reverse voltage. This value ensures compatibility with 12 V and 15 V nominal systems while providing sufficient margin before clamping initiates. The SMAJ18-E3/5A maintains ≤1.0 µA reverse leakage at this voltage, preserving signal integrity in low-power sensing circuits.

How does the clamping voltage of SMAJ18-E3/5A compare to its breakdown voltage?

The SMAJ18-E3/5A exhibits a breakdown voltage (V_BR) range of 20.0–24.4 V at 1 mA test current, while its maximum clamping voltage (V_C) is 32.2 V at 12.4 A peak pulse current. This results in a clamping ratio of approximately 1.79, indicating effective voltage limiting during surge events. The SMAJ18-E3/5A achieves this with low incremental surge resistance, minimizing overshoot beyond V_C during fast transients.

Is SMAJ18-E3/5A suitable for automotive applications?

The SMAJ18-E3/5A is rated for commercial-grade operation and meets RoHS and JESD201 Class 1A whisker testing, but it is not AEC-Q101 qualified. For automotive applications requiring qualification, the HE3-suffix variant (e.g., SMAJ18HE3/5A) must be used. The SMAJ18-E3/5A remains appropriate for non-safety-critical automotive subsystems such as infotainment power rails or cabin sensor interfaces where full qualification is not mandated.

What is the peak pulse current rating of SMAJ18-E3/5A under standard test conditions?

The SMAJ18-E3/5A supports a peak pulse current (I_PPM) of 12.4 A when subjected to a 10/1000 µs waveform, measured at 25 °C ambient and mounted on 0.2 × 0.2" copper pads. This rating corresponds to its 400 W peak pulse power capability. Derating applies above 25 °C per Figure 2 in the datasheet, and actual I_PPM decreases linearly with increasing junction temperature. The SMAJ18-E3/5A sustains this performance without degradation when used within its specified thermal limits.

Does SMAJ18-E3/5A have polarity marking, and how is it oriented in circuit?

Yes, the SMAJ18-E3/5A is unidirectional and features a cathode band marking on the DO-214AC (SMA) package body. During circuit integration, the banded end must be connected to the line being protected (e.g., 12 V rail), while the anode connects to ground or the return path. This orientation enables avalanche conduction only during reverse overvoltage events, preventing forward conduction during normal operation. Incorrect polarity will render the SMAJ18-E3/5A ineffective for transient suppression.

SMAJ18-E3/5A Specifications

Product attributes: Attribute value

Manufacturer:: Vishay General Semiconductor - Diodes Division

Package/Case:: DO-214AC, SMA

Series:: TransZorb®

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Type:: Zener

Unidirectional Channels:: 1

Bidirectional Channels:: -

Voltage - Reverse Standoff (Typ):: 18V

Voltage - Breakdown (Min):: 20V

Voltage - Clamping (Max) @ Ipp:: 32.2V

Current - Peak Pulse (10/1000µs):: 12.4A

Power - Peak Pulse:: 400W

Power Line Protection:: No

Applications:: General Purpose

Capacitance @ Frequency:: -

Operating Temperature:: -55°C ~ 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: DO-214AC (SMA)

SMAJ18-E3/5A FAQ

1.How can I place an order for SMAJ18-E3/5A through Aetrix?

Please submit a Request for Quotation (RFQ) for SMAJ18-E3/5A 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 SMAJ18-E3/5A reliable?

The price and inventory of SMAJ18-E3/5A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ18-E3/5A is usually 5 days.

3.What payment methods are accepted for SMAJ18-E3/5A?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ18-E3/5A transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for SMAJ18-E3/5A?

SMAJ18-E3/5A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your SMAJ18-E3/5A 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 SMAJ18-E3/5A?

For technical support, including SMAJ18-E3/5A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ18-E3/5A requirements.

6.How does Aetrix verify that SMAJ18-E3/5A is sourced from the original manufacturer or authorized distributors?

All SMAJ18-E3/5A 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 SMAJ18-E3/5A meets industry standards.

7.What is the process for return or replacement of SMAJ18-E3/5A?

All SMAJ18-E3/5A units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ18-E3/5A, 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 SMAJ18-E3/5A part is unused and in its original packaging.

Return procedure for SMAJ18-E3/5A:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

Tech Hub

2026-09-11 Comparator Circuit: Voltage Thresholds, Op-Amp Differences, LM393 and Practical Design

Comparator circuit design covering voltage thresholds, input limits, open-collector outputs, LM393 wiring, op-amp differences, hysteresis, timing, window detection and practical fault diagnosis.

2026-09-10 Schmitt Trigger Explained: Hysteresis, Circuits, Inverters and Applications

Schmitt triggers use separate rising and falling thresholds to stabilize slow or noisy signals. This guide covers hysteresis, 74HC14 and 74HCT14 selection, comparator calculations, RC oscillators and p…

2026-09-09 Counterfeit Electronic Components: How to Detect, Authenticate, and Test Suspect Parts

Counterfeit components can hide behind convincing markings and passing basic function tests. This engineering reference covers source traceability, external inspection, X-ray, XRF, electrical testing, …

2026-09-08 Obsolete Electronic Components: How to Source and Evaluate Replacements

A practical engineering and sourcing framework covering lifecycle verification, lifetime-buy calculations, replacement qualification, supplier checks and counterfeit-risk controls.

2026-09-07 TTL vs CMOS Logic Levels: 74HC and 74HCT Compatibility Explained

TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.

2026-09-04 Logic Level Shifter: How to Connect 3.3V and 5V Logic Safely

A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.

2026-09-03 74HC595 vs TPIC6B595: Output Drive, Pinout, Current, and Load Selection

The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…

2026-09-02 74HC595 Pinout, Timing, Output Current, and Applications

The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…

2026-09-01 Latch vs Flip-Flop: Timing, Differences and Design Choices

A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…

2026-08-30 D Latch Circuit: Truth Table, Timing, ICs and Applications

A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …