My Inquiry
My Account
STMicroelectronics SM15T18AY
- Part No.:
- SM15T18AY
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-214AB, SMC
- Datasheet:
-
SM15T18AY.pdf
- Description:
- TVS DIODE 15.3VWM 32.5VC SMC
- Quantity:
- Payment:
- Shipping:
Inventory:7,478
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
SM15T18AY from STMicroelectronics is a unidirectional automotive-grade transient voltage suppressor (TVS) diode in SMC package, designed for ISO 7637-2 pulse protection in 12 V vehicle systems. It features a 18 V nominal breakdown voltage (VBR = 15.3–18.9 V), 25.2 A peak pulse current (IPP) at 10/1000 µs, 32.5 A at 8/20 µs, clamping voltage of 25.2 V (max), and leakage current ≤0.2 µA at 25 °C - deployed in engine control units and body electronics to absorb load dump and inductive switching surges.
For engineers reviewing the SM15T18AY datasheet, SM15T18AY pinout, SM15T18AY application, or SM15T18AY equivalent, this page delivers verified electrical parameters, AEC-Q101 qualification evidence, ISO 10605 ESD robustness (±30 kV), junction temperature derating curves, and real-world automotive surge immunity per ISO 7637-2 Pulse 1/2a/3a/3b - all critical for front-end protection design in harsh automotive environments.
Technical Context
This TVS operates as a unidirectional clamping device with avalanche breakdown behavior, optimized for low dynamic resistance (RD = 0.106 Ω at 10/1000 µs) and stable VCL across temperature (αT = 8.8 × 10−4/°C). Its planar silicon structure ensures low leakage and high Tj capability up to +150 °C, enabling reliable operation under sustained thermal stress in under-hood applications.
It meets IEC 61000-4-4 Level 4 (4 kV), exceeds ISO 10605 Level 4 (±30 kV air/contact discharge), and supports full ISO 7637-2 compliance for 12 V battery systems - including Pulse 1 (−150 V), Pulse 2a (+112 V), Pulse 3a (−220 V), and Pulse 3b (+150 V) - without requiring external series impedance.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VBR (min/typ/max) | 15.3 / 17.1 / 18.9 V - defines precise clamping onset threshold at 1 mA; enables accurate overvoltage margining against 12 V rail transients. |
| VCL @ 10/1000 µs | 25.2 V max - limits protected circuit voltage during 1500 W surge; ensures downstream ICs (e.g., CAN transceivers) remain below absolute maximum ratings. |
| IPP @ 10/1000 µs | 25.2 A - sustains 1500 W peak power at Tamb = 25 °C; derates to ~1250 W at Tj = 150 °C per Figure 3. |
| IPP @ 8/20 µs | 32.5 A - handles high-energy lightning-like transients (10 kW); critical for alternator load dump suppression. |
| RD | 0.106 Ω - low dynamic resistance minimizes VCL overshoot and improves clamping precision during fast-rising surges. |
| IR @ VRM | 0.2 µA max at 25 °C - ultra-low leakage preserves battery life in always-on automotive modules (e.g., telematics, gateway ECUs). |
| Tj range | −55 to +150 °C - validated AEC-Q101 operation enables direct mounting on high-temp PCB zones near power stages or engine compartments. |
Pinout & Package
SM15T18AY uses the industry-standard SMC (DO-214AB) surface-mount package with two terminals: Cathode (K) and Anode (A). The package measures 5.55–6.25 mm × 7.75–8.15 mm × 2.45 mm max height and is compatible with IPC7531 footprint and JEDEC registered outline.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode (A) | Reference node for unidirectional clamping | Connected to ground or low-side return path; defines polarity-sensitive surge shunting direction toward GND. |
| Cathode (K) | Surge input terminal | Connected to protected line (e.g., LIN bus, sensor supply); avalanche conduction occurs when K-to-A voltage exceeds VBR. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive use across temperature, humidity, mechanical shock, and lifetime reliability per JESD22 standards. |
| ISO 7637-2 compliant | Withstands Pulse 1 (−150 V), Pulse 2a (+112 V), Pulse 3a (−220 V), and Pulse 3b (+150 V) without degradation. |
| ±30 kV ESD immunity | Exceeds ISO 10605 Level 4 for both air and contact discharge - eliminates need for secondary ESD protection on sensitive inputs. |
| Low RD (0.106 Ω) | Reduces clamping voltage rise during fast transients, improving protection margin for 3.3 V/5 V logic interfaces. |
| Matte tin lead finish | Meets J-STD-002, JESD22-B102 E3, and MIL-STD-750 Method 2026 - ensures solderability and whisker resistance in high-reliability assembly. |
Applications
| Engine Control Unit (ECU) Power Input | Body Control Module (BCM) Sensor Lines |
|---|---|
|
Use Scenario: Protects 12 V supply rail of diesel/gasoline engine ECUs against alternator load dump and inductive kickback. IC Role / Device Role / Timing Role: Unidirectional TVS clamps negative-going transients to ground while blocking reverse current during normal operation. Use Value: Prevents latch-up or permanent damage to MCU power regulators and CAN transceivers during ISO 7637-2 Pulse 1 and Pulse 3a events. |
Use Scenario: Shields analog sensor inputs (e.g., temperature, pressure) in BCMs from ESD and wiring harness coupling. IC Role / Device Role / Timing Role: Fast-response avalanche diode diverts ±30 kV ESD strikes before reaching ADC front-end or op-amp buffers. Use Value: Maintains signal integrity and avoids system resets caused by ESD-induced latch-up in 5 V sensor interface circuits. |
| Automotive LIN Bus Transceiver Protection | Infotainment System Power Rail |
|
Use Scenario: Installed on LIN bus lines (e.g., door module communication) to suppress coupled transients from adjacent high-current loads. IC Role / Device Role / Timing Role: Clamps induced surges to <25.2 V within nanoseconds, preserving LIN physical layer compliance (ISO 17987-4). Use Value: Ensures uninterrupted serial communication during cranking or relay switching, avoiding bus errors and diagnostic trouble codes. |
Use Scenario: Guards 5 V/3.3 V DC-DC converter outputs powering head unit processors and display drivers. IC Role / Device Role / Timing Role: Absorbs 10 kW 8/20 µs surges from nearby motor actuation, preventing overvoltage shutdown of PMICs. Use Value: Eliminates need for redundant overvoltage protection ICs, reducing BOM count and PCB area in space-constrained infotainment modules. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar unidirectional TVS diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ18A | Lower peak power (400 W), higher VCL (29.2 V), same SMC package but non-AEC-Q101 rated. | Limited to non-automotive industrial use; insufficient for ISO 7637-2 Pulse 1 (−150 V) due to lower IPP and higher clamping. | Select only for cost-sensitive consumer or commercial designs where AEC-Q101 and 1500 W surge rating are not required. |
| 1.5KE18A | Higher VCL (27.6 V), larger DO-201 package (7.75 mm × 10.29 mm), no AEC-Q101 qualification, lead-free plating not specified. | Not suitable for automated SMT assembly; incompatible with IPC7531 footprint; lacks ESD robustness data per ISO 10605. | Use only in legacy through-hole designs where board rework is acceptable and automotive qualification is unnecessary. |
Compared with SMAJ18A and 1.5KE18A, SM15T18AY delivers 3.75× higher peak power, AEC-Q101 validation, and guaranteed ±30 kV ESD performance - making it the sole choice for new automotive designs requiring full ISO 7637-2 and ISO 10605 compliance in SMC form factor.
Availability
SM15T18AY is available at Aetrix Electronics and suitable for engine control units, body control modules, LIN bus interfaces, and infotainment power rails requiring stable component supply under AEC-Q101-compliant automotive production programs.
Supply support for SM15T18AY 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, designing and manufacturing microcontrollers, power devices, sensors, and analog ICs for automotive, industrial, and consumer markets.
The SM15TxxAY series belongs to ST's automotive-grade TVS portfolio, engineered specifically to meet stringent ISO 7637-2 and ISO 10605 requirements for 12 V vehicle electrical systems - emphasizing reliability, low leakage, and high-temperature stability.
FAQ
What is the maximum clamping voltage of SM15T18AY at 25.2 A (10/1000 µs)?
The maximum clamping voltage (VCL) is 25.2 V under 10/1000 µs waveform at Tamb = 25 °C, as specified in Table 2 of DS6928 Rev 6. This value increases linearly with junction temperature using αT = 8.8 × 10−4/°C, reaching ~27.5 V at Tj = 150 °C.
Does SM15T18AY support bidirectional surge protection?
No - SM15T18AY is strictly unidirectional. Its marking "MEEY" and ordering code suffix "AY" confirm unidirectional configuration. For bidirectional protection, ST offers SM15T18CAY (marked "BEEY"), which provides symmetrical clamping for AC-coupled or floating lines.
How does SM15T18AY perform under ISO 7637-2 Pulse 3b (+150 V)?
SM15T18AY fully complies with ISO 7637-2 Pulse 3b (150 V, 50 Ω source, 15 ms duration) per manufacturer characterization. Its 1500 W peak power rating and low RD ensure effective clamping below 25.2 V, protecting downstream 5 V/3.3 V logic without requiring additional series impedance.
Is the SMC package of SM15T18AY compatible with standard reflow profiles?
Yes - SM15T18AY follows ST's ECOPACK reflow profile (Figure 25), with peak temperature of 240–245 °C for ≤3 seconds and ramp rates ≤3 °C/s. It meets J-STD-020 MSL Level 1 and requires no pre-bake, supporting standard lead-free assembly processes on FR4 PCBs.
SM15T18AY 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:
- 1
- Bidirectional Channels:
- -
- 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
SM15T18AY FAQ
1.How can I place an order for SM15T18AY through Aetrix?
Please submit a Request for Quotation (RFQ) for SM15T18AY 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 SM15T18AY reliable?
The price and inventory of SM15T18AY are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SM15T18AY is usually 5 days.
3.What payment methods are accepted for SM15T18AY?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SM15T18AY transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SM15T18AY?
SM15T18AY orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SM15T18AY 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 SM15T18AY?
For technical support, including SM15T18AY datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SM15T18AY requirements.
6.How does Aetrix verify that SM15T18AY is sourced from the original manufacturer or authorized distributors?
All SM15T18AY 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 SM15T18AY meets industry standards.
7.What is the process for return or replacement of SM15T18AY?
All SM15T18AY units undergo pre-shipment inspection (PSI). If there is an issue with SM15T18AY, 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 SM15T18AY part is unused and in its original packaging.
Return procedure for SM15T18AY:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SM15T18AY Tags
-
ESD9B5.0ST5G
onsemi
-
DESD3V3E1BL-7B
Diodes Incorporated
-
ESD5Z3.3T1G
onsemi
-
D5V0H1B2LP-7B
Diodes Incorporated
-
D5V0P1B2LP-7B
Diodes Incorporated
-
DESD5V0U1BA-7
Diodes Incorporated
-
ESD5Z5.0T1G
onsemi
-
DESD5V0U1BB-7
Diodes Incorporated
-
D12V0L1B2LP-7B
Diodes Incorporated
-
PESD2V0Y1BSFYL
Nexperia USA Inc.
-
DF2S5M4CT,L3F
Toshiba Semiconductor and Storage
-
D5V0L1B2WS-7
Diodes Incorporated
Tech Hub
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.
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…
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…
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…
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 …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
