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

STMicroelectronics SM15T18CAY

Name: SM15T18CAY
Brand: STMicroelectronics
SKU: SM15T18CAY
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: SM15T18CAY

Manufacturer:: STMicroelectronics

Category:: TVS Diodes

Package:: DO-214AB, SMC

Datasheet:: SM15T18CAY.pdf

Description:: TVS DIODE 15.3VWM 32.5VC SMC

Quantity:: RFQ Add To RFQ list

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Inventory:4,584

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Product details

Overview

SM15T18CAY from STMicroelectronics is a bidirectional automotive-grade transient voltage suppression (TVS) diode in SMC package, designed for ISO 7637-2 pulse protection and ISO 10605 ESD immunity in 12 V/24 V vehicle systems. It features 18 V breakdown voltage (V_BR = 15.3–18.9 V), 32.5 A peak pulse current (I_PP) at 8/20 µs, 25.2 V clamping voltage (V_CL) at 10/1000 µs, and 1500 W peak pulse power rating.

For engineers reviewing the SM15T18CAY datasheet, SM15T18CAY pinout, SM15T18CAY application, or SM15T18CAY equivalent, key selection criteria include bidirectional surge clamping capability, AEC-Q101 qualification, low leakage (<1 µA at 85 °C), high junction temperature operation (T_j up to 150 °C), and compliance with ISO 7637-2 Pulse 1/2a/3a/3b and ISO 10605 ±30 kV ESD levels.

Technical Context

This bidirectional TVS diode uses planar silicon technology to achieve stable V_BR temperature coefficient (α_T = 8.8 × 10⁻⁴/°C) and low dynamic resistance (R_D = 0.044 Ω at 10/1000 µs). Its symmetrical I-V characteristics enable identical clamping performance in both polarities, critical for protecting differential bus lines like LIN or sensor interfaces against reverse-polarity transients and double-ended surges.

The device operates across −55 °C to +150 °C junction temperature range and maintains ≤1 µA leakage at 85 °C, supporting long-term reliability in under-hood environments. Its SMC package provides thermal robustness with 0.25 g mass and JEDEC-compliant footprint, enabling effective heat dissipation during repetitive 10/1000 µs pulses up to 1250 W at T_j = 150 °C.

Key Specifications

Parameter	Value and Actual Design Meaning
V_BR (min/typ/max)	15.3 / 17.1 / 18.9 V at 1 mA - defines precise voltage threshold for avalanche conduction onset
V_CL @ 10/1000 µs	25.2 V at 1 A - maximum clamped voltage seen by protected circuit during slow surge events
I_PP @ 8/20 µs	32.5 A - peak current handling capacity for fast ESD-like transients per ISO 10605
P_PP (10/1000 µs)	1500 W - sustained surge energy absorption without degradation at T_amb = 25 °C
I_R @ V_RM	0.2 µA at 25 °C, 1 µA at 85 °C - ensures minimal loading on high-impedance automotive signal paths
T_j max	+150 °C - enables placement near heat sources (e.g., ECUs, power modules) without derating
Standards Compliance	AEC-Q101 qualified; ISO 10605 ±30 kV (air/contact); ISO 7637-2 Pulse 1/2a/3a/3b; IEC 61000-4-4 Level 4

Pinout & Package

SM15T18CAY is housed in an SMC (DO-214AB) surface-mount package with two terminals: Cathode (K) and Anode (A), arranged symmetrically for bidirectional operation. The package measures 5.55–6.25 mm (L) × 7.75–8.15 mm (W) × 2.45 mm (H) and features matte tin-plated leads compliant with J-STD-002 and MIL-STD-750 Method 2026.

Pin/Terminal	Circuit Role	Design Meaning
Anode (A)	Positive terminal in forward bias; forms symmetrical junction with cathode	Enables identical clamping behavior for positive and negative transients - no polarity dependency
Cathode (K)	Negative terminal in forward bias; forms symmetrical junction with anode	Provides low-inductance path to ground or reference rail during bidirectional surge events

Key Features

Feature	Design Value
AEC-Q101 qualification	Validated for automotive under-hood use with extended temperature cycling, humidity, and mechanical shock testing
Bidirectional clamping	Identical V_CL and I_PP response for ± polarity surges - eliminates need for dual-device placement
Low leakage current	≤1 µA at 85 °C ensures negligible DC loading on CAN/LIN/sensor reference networks
High T_j capability	Rated for continuous operation up to +150 °C - supports integration into compact, thermally constrained ECUs
ISO 7637-2 Pulse 3b support	Clamps +150 V transients (12 V system) without failure - protects against load-dump-induced overvoltage

Applications

Automotive Body Control Module (BCM)

Engine Control Unit (ECU) Sensor Interface

Use Scenario: Protecting LIN bus lines from battery reverse connection and alternator load dump transients.

IC Role / Device Role / Timing Role: Bidirectional voltage clamp placed between LIN transceiver and connector, limiting line voltage to safe levels during ±150 V ISO 7637-2 Pulse 3b events.

Use Value: Prevents LIN transceiver latch-up or permanent damage while maintaining <1 µA standby leakage to preserve sleep-mode current budget.

Use Scenario: Safeguarding analog pressure/temperature sensor inputs against ESD and ignition coil coupling noise.

IC Role / Device Role / Timing Role: Low-capacitance (≈200 pF at 0 V) bidirectional TVS placed at sensor harness entry point to shunt fast transients before reaching ADC front-end.

Use Value: Maintains signal integrity with <25.2 V clamping during 10/1000 µs surges, avoiding ADC saturation or microcontroller reset.

Infotainment Head Unit Power Input

ADAS Camera Module Data Lines

Use Scenario: Suppressing 12 V supply rail transients caused by relay switching and motor actuation in dashboard electronics.

IC Role / Device Role / Timing Role: Primary surge suppressor on main 12 V input, coordinated with downstream ceramic capacitors to absorb 1500 W pulses per ISO 7637-2 Pulse 1 (−150 V).

Use Value: Enables single-device protection with 1250 W capability at T_j = 150 °C, reducing BOM count versus multi-stage solutions.

Use Scenario: Shielding FPD-Link III or GMSL serial video data lines from ESD events during assembly and field service.

IC Role / Device Role / Timing Role: Bidirectional TVS mounted directly at board edge connector, providing ±30 kV air/contact ESD immunity per ISO 10605 without degrading 3 Gbps signal integrity.

Use Value: Achieves <0.044 Ω dynamic resistance to minimize V_CL overshoot, preserving eye diagram margin for high-speed video transmission.

Equivalent & Alternatives

The following parts are listed as comparable options for similar bidirectional TVS diode applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
SMAJ18CA	Same SMC package but lower P_PP (400 W), higher V_CL (32.4 V at 10/1000 µs), non-AEC-Q101	Limited to non-automotive industrial use; insufficient for ISO 7637-2 Pulse 1/3b compliance	Select only for cost-sensitive non-automotive designs where 1500 W surge rating is not required.
TPSMD18CA	Higher V_CL (28.5 V), lower I_PP (28.2 A), same AEC-Q101 grade but larger SOD-123FL footprint	Requires PCB redesign due to different package; less effective clamping for 12 V rail protection	Choose when board space allows larger footprint and higher clamping voltage is acceptable for legacy system compatibility.

Compared with SMAJ18CA and TPSMD18CA, SM15T18CAY delivers superior surge robustness (1500 W vs. 400 W/600 W), tighter clamping (25.2 V vs. 32.4 V/28.5 V), and guaranteed AEC-Q101 qualification - making it the optimal choice for new automotive designs requiring full ISO 7637-2 and ISO 10605 compliance.

Availability

SM15T18CAY is available at Aetrix Electronics and suitable for automotive body control modules, engine control units, infotainment power supplies, and ADAS camera interfaces requiring stable component supply with full AEC-Q101 traceability and ISO-compliant surge protection.

Supply support for SM15T18CAY 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, specializing in automotive, industrial, and power management ICs with strong vertical integration and manufacturing control.

The SM15Txx series belongs to ST's automotive-grade TVS portfolio, engineered specifically for robust transient suppression in harsh vehicle electrical environments - targeting ISO 7637-2, ISO 10605, and IEC 61000-4-4 compliance in ECU, BCM, and ADAS subsystems.

FAQ

What is the difference between SM15T18AY and SM15T18CAY?

SM15T18AY is unidirectional (anode-to-cathode conduction only), while SM15T18CAY is bidirectional - offering symmetrical clamping for both positive and negative transients. The 'C' suffix explicitly denotes bidirectional functionality, critical for protecting AC-coupled or differential signal lines without polarity constraints.

Does SM15T18CAY require external series impedance for optimal ESD protection?

No external series resistor is required for basic ISO 10605 compliance, as the device's low dynamic resistance (0.044 Ω) and fast response (<1 ns) enable direct shunting of ±30 kV ESD events. However, a small series resistor (e.g., 10 Ω) may be added to limit peak current in ultra-low-impedance test fixtures without affecting functional protection.

Can SM15T18CAY be used in 24 V commercial vehicle systems?

Yes - its 18 V nominal breakdown and 25.2 V clamping voltage provide adequate margin above 24 V nominal rail (typically 20–28 V), and its AEC-Q101 qualification covers extended temperature and vibration requirements common in heavy-duty vehicles. Pulse 3b testing at +150 V confirms suitability for 24 V load-dump scenarios.

How does junction temperature affect clamping voltage in SM15T18CAY?

V_CL increases linearly with junction temperature at a rate of α_T = 8.8 × 10⁻⁴/°C. At T_j = 150 °C, V_CL rises by ≈1.1 V above its 25 °C value (25.2 V → ~26.3 V), remaining well within safe limits for 12 V system protection while preserving margin against downstream IC absolute maximum ratings.

SM15T18CAY Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Package/Case:: DO-214AB, SMC

Series:: SM15TY, TRANSIL™

Packaging:: Tape & Reel (TR)

Product Status:: Active

Type:: Zener

Unidirectional Channels:: -

Bidirectional Channels:: 1

Voltage - Reverse Standoff (Typ):: 15.3V

Voltage - Breakdown (Min):: 17.1V

Voltage - Clamping (Max) @ Ipp:: 32.5V

Current - Peak Pulse (10/1000µs):: 308A (8/20µs)

Power - Peak Pulse:: 1500W (1.5kW)

Power Line Protection:: No

Applications:: -

Capacitance @ Frequency:: -

Operating Temperature:: -40°C ~ 150°C (TJ)

Grade:: Automotive

Qualification:: AEC-Q101

Mounting Type:: Surface Mount

Supplier Device Package:: SMC

SM15T18CAY FAQ

1.How can I place an order for SM15T18CAY through Aetrix?

Please submit a Request for Quotation (RFQ) for SM15T18CAY 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 SM15T18CAY reliable?

The price and inventory of SM15T18CAY are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SM15T18CAY is usually 5 days.

3.What payment methods are accepted for SM15T18CAY?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SM15T18CAY transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for SM15T18CAY?

SM15T18CAY orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your SM15T18CAY 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 SM15T18CAY?

For technical support, including SM15T18CAY datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SM15T18CAY requirements.

6.How does Aetrix verify that SM15T18CAY is sourced from the original manufacturer or authorized distributors?

All SM15T18CAY 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 SM15T18CAY meets industry standards.

7.What is the process for return or replacement of SM15T18CAY?

All SM15T18CAY units undergo pre-shipment inspection (PSI). If there is an issue with SM15T18CAY, 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 SM15T18CAY part is unused and in its original packaging.

Return procedure for SM15T18CAY:

1.Submit a request within 90 days.

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

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