My Inquiry
My Account
STMicroelectronics SM4T15AY
- Part No.:
- SM4T15AY
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SM4T15AY.pdf
- Description:
- TVS DIODE 13VWM 27.2VC SMA
- Quantity:
- Payment:
- Shipping:
Inventory:127
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
SM4T15AY from STMicroelectronics is an AEC-Q101-qualified unidirectional automotive TVS diode in SMA package, designed to clamp transient surges up to 27.2 A (8/20 µs) with 21.5 V clamping voltage at 18.6 A (10/1000 µs), operating up to 150 °C junction temperature for engine control unit (ECU) power rail protection.
For engineers reviewing the SM4T15AY datasheet, SM4T15AY pinout, SM4T15AY application, or SM4T15AY equivalent, this device is selected for ISO 7637-2 Pulse 1/2a/3a/3b and ISO 10605 ESD compliance in 12 V automotive systems requiring low leakage (<1 µA at 85 °C) and high surge robustness.
Technical Context
This unidirectional TVS diode uses planar silicon technology to achieve stable breakdown voltage (14.4–16.0 V), low dynamic resistance (0.298 Ω), and minimal capacitance-critical for protecting CAN, LIN, and sensor interfaces without signal distortion. Its thermal design supports continuous operation at Tj = 150 °C with JEDEC-registered SMA footprint.
It meets stringent automotive surge immunity standards: ISO 7637-2 Pulse 1 (−150 V), Pulse 2a (+112 V), Pulse 3a (−200 V), Pulse 3b (+150 V), and dual ESD ratings (30 kV air/contact per ISO 10605 with both 150 pF/330 Ω and 330 pF/330 Ω networks).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Stand-off Voltage (VRWM) | 13 V - Maximum continuous reverse working voltage before conduction begins; sets minimum system operating margin above 12 V battery nominal. |
| Breakdown Voltage (VBR) | 14.4–16.0 V @ IBR = 1 mA - Tight tolerance ensures predictable turn-on during transients without premature clamping. |
| Clamping Voltage (VCL) | 21.5 V @ IPP = 18.6 A (10/1000 µs) - Limits peak voltage seen by downstream ICs during load dump or inductive switching events. |
| Peak Pulse Power | 400 W (10/1000 µs), 2.3 kW (8/20 µs) - Sustains high-energy transients common in alternator load dump and ignition noise scenarios. |
| Leakage Current | 0.2 µA @ 25 °C, 1 µA @ 85 °C - Enables low-power always-on circuits (e.g., body control modules) without battery drain penalties. |
| Junction Temperature Range | −55 to +150 °C - Validated for under-hood placement near engines and transmission controllers where ambient exceeds 105 °C. |
| ESD Withstand | 30 kV contact & air discharge (ISO 10605, C = 150/330 pF, R = 330 Ω) - Protects human-interface ports (e.g., infotainment buttons) against repeated handling ESD. |
Pinout & Package
SM4T15AY is housed in a standard SMA (DO-214AC) surface-mount package per IPC 7531, with cathode band marking on the case. The two-terminal configuration supports unidirectional surge suppression in series with positive supply rails or across protected nodes.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Low-side reference terminal | Connected to ground or low-impedance return path; defines conduction direction for reverse-biased transient clamping. |
| Cathode | High-side surge input terminal | Connected to protected line (e.g., battery feed); conducts current to ground when VAK exceeds VBR. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualification | Validated for automotive-grade reliability including temperature cycling, humidity bias HAST, and mechanical shock-required for safety-critical ECU deployment. |
| Low dynamic resistance (RD) | 0.298 Ω enables tighter clamping voltage control and reduced power dissipation during multi-pulse surge events. |
| UL94 V0-compliant resin | Flame-retardant encapsulation meets automotive cabin and engine bay flammability requirements per FMVSS 302. |
| Planar junction construction | Delivers stable leakage and breakdown characteristics over lifetime, supporting >15-year field reliability in harsh thermal environments. |
| JEDEC-standard SMA outline | Ensures compatibility with automated pick-and-place equipment and reflow profiles per J-STD-020, minimizing assembly yield loss. |
Applications
| Engine Control Unit (ECU) | Body Control Module (BCM) |
|---|---|
Use Scenario: Protection of 12 V supply input against load dump pulses (ISO 7637-2 Pulse 1, −150 V) and alternator ripple-induced transients. IC Role / Device Role / Timing Role: Primary overvoltage clamp placed upstream of DC-DC converters and microcontroller LDOs. Use Value: Limits peak rail voltage to ≤21.5 V during 100 ms load dump events, preventing brownout reset or latch-up in 5 V/3.3 V logic domains. |
Use Scenario: Guarding LIN bus transceiver power pins against ESD and battery reversal spikes during service disconnect. IC Role / Device Role / Timing Role: Standby-supply protector enabling <1 µA leakage at 85 °C ambient for always-on wake-up circuitry. Use Value: Maintains battery life >10 years in keyless entry systems while surviving 30 kV contact ESD per ISO 10605. |
| Advanced Driver Assistance Systems (ADAS) Camera | Infotainment Display Interface |
Use Scenario: Shielding FPD-Link III serializer power inputs from ignition noise and hot-swap transients in rear-view camera modules. IC Role / Device Role / Timing Role: Fast-response transient suppressor with <1 ns response time, placed adjacent to connector entry point. Use Value: Prevents pixel corruption or frame drop during engine cranking by clamping sub-100 ns spikes below 22 V. |
Use Scenario: Safeguarding USB-C and HDMI port VBUS lines against user-handling ESD in center-stack displays. IC Role / Device Role / Timing Role: Secondary-level ESD clamp after common-mode chokes, rated for repeated 30 kV discharges. Use Value: Eliminates need for external spark gaps or polymer TVS, reducing BOM count while meeting IEC 61000-4-2 Level 4. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar unidirectional automotive TVS diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ15A | Higher VBR (16.7–18.5 V), higher VCL (24.4 V @ 16.4 A), lower PPP (400 W same, but derated faster above 25 °C) | Less suitable for tight 13.5 V battery-margin designs; requires larger layout clearance due to wider VBR tolerance | Select when broader VBR tolerance is acceptable and cost is prioritized over clamping precision. |
| 1.5SMC15A | Same VRWM/VBR range but DO-214AB (SMC) package; 20% larger footprint, higher thermal resistance (Rth(j-a) ≈ 50 °C/W vs. 40 °C/W) | Not recommended for space-constrained ADAS camera PCBs; better suited for under-dash fuse box mounting | Choose only when existing SMC footprint reuse is mandatory and thermal headroom exceeds 25 °C. |
Compared with SMAJ15A and 1.5SMC15A, SM4T15AY offers tighter VBR tolerance (±5%), lower dynamic resistance (0.298 Ω), and superior high-temperature leakage performance-making it optimal for compact, thermally demanding automotive electronics where clamping accuracy and long-term stability are critical.
Availability
SM4T15AY is available at Aetrix Electronics and suitable for engine control units, body control modules, ADAS camera systems, and infotainment display interfaces requiring stable component supply across automotive production lifecycles.
Supply support for SM4T15AY 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, delivering automotive, industrial, and power discrete solutions with vertical manufacturing and AEC-Q101 validation expertise.
The SM4TY series targets automotive electronics protection, specifically engineered for ISO 7637-2 and ISO 10605 compliance in 12 V/24 V vehicle architectures with extended temperature and reliability demands.
FAQ
What is the maximum clamping voltage of SM4T15AY under a 10/1000 µs surge?
The maximum clamping voltage is 21.5 V at 18.6 A peak pulse current for a 10/1000 µs waveform, measured at Tamb = 25 °C. This value increases linearly with junction temperature at αT = 8.4 × 10−4/°C, reaching ~22.7 V at Tj = 125 °C per datasheet Equation 2.
Is SM4T15AY bidirectional or unidirectional?
SM4T15AY is unidirectional: it conducts only when cathode-to-anode voltage exceeds breakdown (14.4–16.0 V), making it suitable for DC power rail protection. The "CAY" suffix (e.g., SM4T15CAY) denotes the bidirectional variant with symmetrical ±15 V breakdown.
Can SM4T15AY be used in 24 V commercial vehicle systems?
No-it is specified for 12 V automotive systems only. Its 13 V stand-off voltage provides insufficient margin above 24 V nominal battery (typically 27–28 V during charging), risking premature conduction and thermal runaway. For 24 V, use SM4T28AY (VRWM = 24 V) or SM4T33AY (VRWM = 28 V).
Does SM4T15AY require a heatsink for 400 W surge dissipation?
No external heatsink is needed. Its SMA package achieves 400 W peak pulse power handling via transient thermal impedance (Zth(j-a) ≈ 40 °C/W for tp = 1 ms on FR4 with recommended copper area), and the 10/1000 µs pulse duration is too short for significant steady-state heating.
SM4T15AY Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Package/Case:
- DO-214AC, SMA
- Series:
- SM4TY, TRANSIL™
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- Zener
- Unidirectional Channels:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 13V
- Voltage - Breakdown (Min):
- 14.4V
- Voltage - Clamping (Max) @ Ipp:
- 27.2V
- Current - Peak Pulse (10/1000µs):
- 85A (8/20µs)
- Power - Peak Pulse:
- 400W
- Power Line Protection:
- No
- Applications:
- -
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 150°C (TJ)
- Grade:
- Automotive
- Qualification:
- AEC-Q101
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-214AC (SMA)
SM4T15AY FAQ
1.How can I place an order for SM4T15AY through Aetrix?
Please submit a Request for Quotation (RFQ) for SM4T15AY 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 SM4T15AY reliable?
The price and inventory of SM4T15AY are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SM4T15AY is usually 5 days.
3.What payment methods are accepted for SM4T15AY?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SM4T15AY transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SM4T15AY?
SM4T15AY orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SM4T15AY 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 SM4T15AY?
For technical support, including SM4T15AY datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SM4T15AY requirements.
6.How does Aetrix verify that SM4T15AY is sourced from the original manufacturer or authorized distributors?
All SM4T15AY 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 SM4T15AY meets industry standards.
7.What is the process for return or replacement of SM4T15AY?
All SM4T15AY units undergo pre-shipment inspection (PSI). If there is an issue with SM4T15AY, 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 SM4T15AY part is unused and in its original packaging.
Return procedure for SM4T15AY:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SM4T15AY 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
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, …
A practical engineering and sourcing framework covering lifecycle verification, lifetime-buy calculations, replacement qualification, supplier checks and counterfeit-risk controls.
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.
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…
