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Taiwan Semiconductor Corporation SMCJ18A
- Part No.:
- SMCJ18A
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AB, SMC
- Datasheet:
-
SMCJ18A.pdf
- Description:
- TVS DIODE 18VWM 29.2VC SMC
- Quantity:
- Payment:
- Shipping:
Inventory:3,152
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Product details
Overview
SMCJ18A from Taiwan Semiconductor is a unidirectional 1500W surface-mount transient voltage suppressor (TVS) diode in DO-214AB (SMC) package, with 18V working stand-off voltage (VWM), 20–22.1V breakdown voltage (VBR), and 29.2V maximum clamping voltage (VC) at 53A peak pulse current. It protects automotive power rails and industrial I/O interfaces against ISO 7637-2 Pulse 1/2a/2b/3a/3b transients.
For engineers reviewing the SMCJ18A datasheet, SMCJ18A pinout, SMCJ18A application, or SMCJ18A equivalent, this page delivers verified electrical parameters, thermal performance data, real-world protection use cases, and validated alternative parts for ESD and surge immunity design in automotive and industrial control systems.
Technical Context
The SMCJ18A uses a glass-passivated silicon junction to achieve fast response (<1.0 ps from 0 V to VBR min) and low leakage (<1 µA at 18 V). Its unidirectional configuration provides forward conduction only during reverse overvoltage events, enabling integration into DC power lines without interfering with normal operation.
Rated for 1500 W peak pulse power (tp = 1 ms), it sustains 53 A peak impulse current (IPPM) while clamping to ≤29.2 V - critical for safeguarding 24 V nominal systems where rail voltage must stay below 30 V during transients. Junction temperature range is –55°C to +150°C, supporting under-hood and industrial ambient conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 18 V - maximum continuous reverse operating voltage before clamping begins; matches 24 V system nominal rails with safety margin |
| VBR min / max | 20 V / 22.1 V @ IT = 1 mA - ensures reliable turn-on above normal operating voltage but below damage threshold of protected ICs |
| VC @ IPPM | 29.2 V @ 53 A - clamping voltage limits downstream component stress during 1 ms surge events per ISO 7637-2 |
| PPK | 1500 W - peak pulse power rating defines energy-handling capability for transient suppression |
| IR @ VWM | <1 µA - ultra-low leakage preserves battery life and avoids false triggering in always-on circuits |
| TJ max | +150 °C - enables placement near heat sources in engine control units or motor drives |
| RθJA | 55 °C/W - thermal resistance informs PCB copper area requirements for sustained power dissipation |
Pinout & Package
DO-214AB (SMC) surface-mount package with cathode band marking; matte tin-plated leads compliant with J-STD-002 solderability; moisture sensitivity level 1 (per J-STD-020); UL 94V-0 molding compound.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction path during clamping | Connected to ground or low-side return; completes surge current path when reverse voltage exceeds VBR |
| Cathode | Protected line connection point | Connected to 24 V rail or signal line; reverse-biased during normal operation, avalanches during overvoltage |
Key Features
| Feature | Design Value |
|---|---|
| Glass-passivated junction | Ensures stable VBR and low IR over lifetime and temperature cycling, critical for automotive qualification |
| ISO 7637-2 compliance (Pulse 1/2a/2b/3a/3b) | Validated for automotive load-dump and inductive-switching immunity testing without external circuitry |
| Fast response time <1.0 ps | Clamps before sensitive logic or analog inputs experience damaging voltage overshoot |
| RoHS and halogen-free (IEC 61249-2-21) | Meets global environmental compliance for industrial and automotive supply chains |
| DO-214AB mechanical robustness | Withstands board flexure and thermal cycling in harsh environments; weight 0.210 g supports automated placement |
Applications
| Automotive Power Rail Protection | Industrial PLC Digital I/O Protection |
|---|---|
Use Scenario: 24 V battery-fed ECUs exposed to load dump and alternator transients per ISO 7637-2. IC Role / Device Role / Timing Role: Unidirectional TVS placed between 24 V rail and chassis ground to clamp surges before they reach power management ICs. Use Value: Limits rail voltage to ≤29.2 V during 53 A transients, preventing latch-up or burnout of buck converters and microcontrollers. | Use Scenario: 24 V digital input modules receiving signals from field sensors in factory automation. IC Role / Device Role / Timing Role: TVS on each input channel to absorb EFT bursts (IEC 61000-4-4) and inductive kickback from solenoid drivers. Use Value: Enables >10 kV ESD and 2 kV EFT immunity without adding RC filters that degrade signal edge rate. |
| LED Driver Overvoltage Clamp | Motor Drive Gate Driver Protection |
Use Scenario: Constant-current LED drivers powered from 24 V bus in commercial lighting fixtures. IC Role / Device Role / Timing Role: SMCJ18A placed across driver input terminals to suppress switching noise and lightning-induced surges. Use Value: Prevents premature failure of high-side MOSFETs and current-sense amplifiers by limiting input voltage excursions to 29.2 V. | Use Scenario: Half-bridge gate drivers controlling 24 V BLDC motors in HVAC blowers or pumps. IC Role / Device Role / Timing Role: TVS on high-side gate drive supply rail to protect level-shifters and bootstrap FETs from Miller-induced spikes. Use Value: Maintains gate oxide integrity by clamping supply rail transients faster than internal ESD diodes can respond. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ18A (Bourns) | Same VWM (18 V), lower PPK (600 W), lower IPPM (32.4 A), higher VC (29.7 V) | Not suitable for ISO 7637-2 Pulse 5a (load dump); limited to lower-energy ESD/EFT scenarios | Select SMBJ18A only for space-constrained designs where 1500 W rating is unnecessary |
| 1.5SMC18A (ON Semiconductor) | Identical VWM (18 V), same PPK (1500 W), same VC (29.2 V), but higher IR (≤5 µA vs. ≤1 µA) | Acceptable for most 24 V systems, though higher leakage may impact ultra-low-power sleep modes | Choose 1.5SMC18A when dual-sourcing is required and leakage tolerance allows up to 5 µA |
Compared with SMBJ18A and 1.5SMC18A, the SMCJ18A offers superior energy handling for automotive load-dump immunity and the lowest leakage among 1500 W-class 18 V TVS diodes - making it optimal for always-on 24 V systems requiring long-term reliability and minimal standby current.
Availability
SMCJ18A is available at Aetrix Electronics and suitable for automotive electronics, industrial PLCs, LED lighting systems, and motor control modules requiring stable component supply and full ISO 7637-2 compliance.
Supply support for SMCJ18A 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
Taiwan Semiconductor Corporation (TSC) is a vertically integrated semiconductor manufacturer specializing in discrete power devices, including TVS diodes, rectifiers, and MOSFETs for automotive and industrial markets.
The SMCJ series was designed specifically for high-energy transient suppression in 12 V/24 V automotive and industrial power systems, emphasizing ruggedness, consistency, and compliance with international surge immunity standards.
FAQ
What is the clamping voltage of the SMCJ18A and why does it matter?
The SMCJ18A has a maximum clamping voltage (VC) of 29.2 V at 53 A peak pulse current. This value defines the highest voltage seen by downstream components during a transient event. For 24 V systems, keeping clamped voltage below 30 V prevents damage to common 30 V-rated power MOSFETs, gate drivers, and LDO regulators - making the SMCJ18A a precise match for robust 24 V rail protection.
Is the SMCJ18A unidirectional or bidirectional?
The SMCJ18A is a unidirectional TVS diode, indicated by the absence of "C" or "CA" suffix. It conducts only in reverse bias above its breakdown voltage and blocks forward current like a standard diode. This configuration is ideal for DC power line protection where polarity is fixed, such as 24 V battery inputs in automotive ECUs.
Does the SMCJ18A meet automotive transient immunity standards?
Yes, the SMCJ18A meets ISO 7637-2 requirements for Pulse 1 (inductive load disconnect), Pulse 2a (sudden load removal), Pulse 2b (supply interruption), Pulse 3a (capacitive coupling), and Pulse 3b (ground noise). Its 1500 W rating and 29.2 V clamping enable direct compliance without additional filtering components in standard 24 V automotive architectures.
What is the thermal resistance of the SMCJ18A and how does it affect layout?
The SMCJ18A has a junction-to-ambient thermal resistance (RθJA) of 55 °C/W. To maintain safe operation during repetitive surges, PCB layout must provide adequate copper area - typically ≥100 mm² of 2 oz copper per terminal - to dissipate heat. The RθJC of 10 °C/W also supports heatsinking via the cathode pad if needed for high-duty-cycle applications.
How does the SMCJ18A compare to the SMCJ18 (non-A) variant?
The SMCJ18A offers tighter breakdown voltage tolerance (20–22.1 V) versus SMCJ18 (20–24.4 V), resulting in more predictable clamping onset and lower worst-case VC. Its lower VBR max improves compatibility with 24 V systems where overvoltage margin is constrained. Both share identical package, power rating, and thermal specs - the "A" suffix denotes enhanced VBR consistency for critical applications.
SMCJ18A Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Taiwan Semiconductor Corporation
- Package/Case:
- DO-214AB, SMC
- Series:
- -
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- 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):
- 51.4A
- Power - Peak Pulse:
- 1500W (1.5kW)
- Power Line Protection:
- No
- Applications:
- General Purpose
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-214AB (SMC)
SMCJ18A FAQ
1.How can I place an order for SMCJ18A through Aetrix?
Please submit a Request for Quotation (RFQ) for SMCJ18A 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 SMCJ18A reliable?
The price and inventory of SMCJ18A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMCJ18A is usually 5 days.
3.What payment methods are accepted for SMCJ18A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMCJ18A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMCJ18A?
SMCJ18A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMCJ18A 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 SMCJ18A?
For technical support, including SMCJ18A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMCJ18A requirements.
6.How does Aetrix verify that SMCJ18A is sourced from the original manufacturer or authorized distributors?
All SMCJ18A 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 SMCJ18A meets industry standards.
7.What is the process for return or replacement of SMCJ18A?
All SMCJ18A units undergo pre-shipment inspection (PSI). If there is an issue with SMCJ18A, 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 SMCJ18A part is unused and in its original packaging.
Return procedure for SMCJ18A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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