My Inquiry
My Account
STMicroelectronics SM4T26AY
- Part No.:
- SM4T26AY
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SM4T26AY.pdf
- Description:
- TVS DIODE 22VWM 48.3VC SMA
- Quantity:
- Payment:
- Shipping:
Inventory:9,729
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
SM4T26AY from STMicroelectronics is an AEC-Q101-qualified unidirectional automotive TVS diode in SMA package, designed to clamp transient surges up to 35.5 V (VCL) at 11.2 A (IPP, 10/1000 µs), with 400 W peak pulse power rating and 0.2 µA leakage at 25 °C. It protects CAN, LIN, and sensor interfaces in 12 V automotive systems against ISO 7637-2 Pulse 1 (−150 V), Pulse 2a (+112 V), and ISO 10605 ESD events.
For engineers reviewing the SM4T26AY datasheet, SM4T26AY pinout, SM4T26AY application, or SM4T26AY equivalent, key selection criteria include clamping voltage at rated surge current, junction temperature derating above 25 °C, unidirectional polarity for DC-biased lines, and compatibility with SMA footprint per IPC 7531.
Technical Context
The SM4T26AY uses planar silicon technology to achieve low leakage (≤0.2 µA at 25 °C) and high thermal stability (Tjmax = 150 °C), enabling long-term reliability in under-hood environments. Its dynamic resistance (RD = 0.76 Ω) and voltage temperature coefficient (αT = 9.6 × 10−4/°C) ensure predictable clamping across −55 °C to +150 °C operating range.
It meets ISO 10605 (150 pF/330 Ω and 330 pF/330 Ω) with ±30 kV air/contact discharge, and ISO 7637-2 Pulse 1 (−150 V), Pulse 2a (+112 V), Pulse 3a (−200 V), and Pulse 3b (+150 V) - all validated for 12 V battery systems where VRM (22 V) exceeds nominal supply.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VBR min / typ / max | 24.4 V / 25.7 V / 27.0 V at IBR = 1 mA - defines minimum breakdown threshold before clamping activation |
| VCL @ 10/1000 µs | 35.5 V at IPP = 11.2 A - maximum clamped voltage seen by protected IC during slow surge |
| VCL @ 8/20 µs | 48.3 V at IPP = 48 A - higher clamping level for fast ESD transients, critical for microcontroller I/O protection |
| RD | 0.76 Ω - dynamic resistance determining voltage rise above VBR under surge current (ΔV = RD × IPP) |
| IR @ VRM | 0.2 µA at 22 V, 25 °C - ultra-low leakage preserves battery life in always-on automotive modules |
| Tjmax | +150 °C - enables placement near heat sources (e.g., engine control units) without derating loss |
| Package | SMA (DO-214AC) - JEDEC-registered surface-mount outline with 5.35 mm × 4.60 mm footprint per IPC 7531 |
Pinout & Package
SMA package: single-sided, two-terminal surface-mount device with cathode band marking; terminals are anode (pin 1) and cathode (pin 2); compatible with standard reflow profiles (peak 240–245 °C).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | DC return path for protected line | Connected to ground or low-impedance reference; carries full surge current during clamping |
| Cathode | Protected signal input | Connected to sensitive node (e.g., CAN_H); reverse-biased during normal operation, avalanches during overvoltage |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualification | Validated for automotive under-hood use including temperature cycling, humidity bias, and mechanical shock |
| Low leakage current | 0.2 µA at 22 V and 25 °C ensures minimal standby power draw in always-on vehicle networks |
| High junction temperature rating | 150 °C continuous operation supports placement on ECUs near power stages without thermal derating |
| UL94 V0-compliant resin | Flame-retardant encapsulation meets automotive safety standards for module-level fire resistance |
| ISO 7637-2 compliance | Withstands defined load-dump and inductive-switching transients in 12 V systems without degradation |
Applications
| Automotive CAN Bus Protection | Body Control Module (BCM) Inputs |
|---|---|
|
Use Scenario: Protecting CAN_H/CAN_L lines in powertrain and chassis ECUs against load dump and ESD. IC Role / Device Role / Timing Role: Unidirectional clamping diode placed between CAN transceiver I/O and connector, referenced to chassis ground. Use Value: Limits VCL to 35.5 V during 10/1000 µs surges, keeping transceiver within absolute maximum ratings while maintaining signal integrity. |
Use Scenario: Safeguarding analog sensor inputs (e.g., ambient temperature, door position) in BCMs exposed to harness-induced transients. IC Role / Device Role / Timing Role: Standoff protection device mounted at PCB edge connector, shunting surges before reaching ADC front-end. Use Value: 0.2 µA leakage avoids measurement offset in µA-range sensor bias circuits; 150 °C rating allows direct placement near connector. |
| Infotainment System USB Interface | 12 V Power Rail Surge Suppression |
|
Use Scenario: ESD protection for USB 2.0 D+/D− lines in head unit or telematics control units. IC Role / Device Role / Timing Role: Bidirectional-capable variant (SM4T26CAY) used for symmetric data lines; unidirectional SM4T26AY applied to VBUS line. Use Value: Clamps 30 kV contact discharge to ≤48.3 V within 8/20 µs, preventing latch-up in USB PHY without adding capacitance that degrades 480 Mbps signaling. |
Use Scenario: Secondary surge suppression on 12 V supply rail downstream of main fuse and primary TVS. IC Role / Device Role / Timing Role: Fast-response clamping element placed after DC-DC converter input, absorbing residual ISO 7637-2 Pulse 3a/b energy. Use Value: 400 W peak power rating handles 200 V/50 ms transients without thermal runaway; SMA package enables compact layout adjacent to power entry point. |
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 |
|---|---|---|---|
| SMAJ26A | VBR = 28.9–32.1 V; VCL = 42.1 V @ 9.5 A (10/1000 µs); RD = 1.07 Ω | Higher clamping voltage and lower surge current rating reduce margin for 12 V system transients | Select when cost sensitivity outweighs clamping performance; verify VCL < IC abs max rating under worst-case Tj |
| 1.5SMC27A | VBR = 28.9–32.1 V; VCL = 42.1 V @ 9.5 A; SMC package (larger than SMA) | SMC footprint requires PCB redesign; higher thermal mass slows response but improves energy handling | Prefer only if legacy board uses SMC; avoid for new designs targeting space-constrained automotive modules |
Compared with SMAJ26A and 1.5SMC27A, SM4T26AY delivers lower clamping (35.5 V vs. ≥42.1 V), tighter VBR tolerance (±5.7% vs. ±10%), and smaller SMA footprint - making it optimal for next-gen automotive nodes where voltage margin and board area are critical.
Availability
SM4T26AY is available at Aetrix Electronics and suitable for automotive CAN bus protection, body control module inputs, infotainment USB interfaces, and 12 V power rail surge suppression requiring stable component supply across production lifecycles.
Supply support for SM4T26AY 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 solutions with vertical manufacturing and broad IP portfolio.
The SM4TY series belongs to ST's automotive-grade transient voltage suppression portfolio, engineered specifically for ISO 7637-2 and ISO 10605 compliance in 12 V vehicle architectures with emphasis on low leakage and high-temperature reliability.
FAQ
Is SM4T26AY bidirectional or unidirectional?
SM4T26AY is unidirectional: it conducts only during reverse-voltage transients on the cathode terminal, making it suitable for DC-biased lines like CAN_H or 12 V supply rails. The bidirectional variant is SM4T26CAY, marked with "DBSY" and intended for symmetric AC-coupled signals such as USB D+/D−.
What is the maximum surge current SM4T26AY can handle?
SM4T26AY sustains 11.2 A peak pulse current (IPP) under the 10/1000 µs waveform at 25 °C, delivering 400 W peak pulse power. At elevated junction temperatures (e.g., 125 °C), derating reduces IPP to ~7.5 A per Figure 3 in DS6927 Rev 6.
Does SM4T26AY require a heatsink for automotive operation?
No external heatsink is required: its SMA package achieves Rth(j-a) ≈ 120 °C/W on standard FR4 with 1 cm² copper per lead (Figure 12), and thermal impedance remains safe under pulsed conditions (Zth(j-a) drops to <10 °C/W for 10 ms pulses). Continuous power dissipation is limited by leakage, not thermal saturation.
How does SM4T26AY compare to SM4T24AY in circuit protection?
SM4T26AY has higher VBR (24.4–27.0 V vs. 22.2–24.6 V for SM4T24AY) and higher VCL (35.5 V vs. 32.4 V), providing greater margin against false triggering on 12 V nominal rails with ripple, while still clamping below 40 V - the typical absolute maximum for automotive transceivers and microcontrollers.
SM4T26AY 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):
- 22V
- Voltage - Breakdown (Min):
- 24.4V
- Voltage - Clamping (Max) @ Ipp:
- 48.3V
- Current - Peak Pulse (10/1000µs):
- 48A (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)
SM4T26AY FAQ
1.How can I place an order for SM4T26AY through Aetrix?
Please submit a Request for Quotation (RFQ) for SM4T26AY 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 SM4T26AY reliable?
The price and inventory of SM4T26AY are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SM4T26AY is usually 5 days.
3.What payment methods are accepted for SM4T26AY?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SM4T26AY transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SM4T26AY?
SM4T26AY orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SM4T26AY 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 SM4T26AY?
For technical support, including SM4T26AY datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SM4T26AY requirements.
6.How does Aetrix verify that SM4T26AY is sourced from the original manufacturer or authorized distributors?
All SM4T26AY 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 SM4T26AY meets industry standards.
7.What is the process for return or replacement of SM4T26AY?
All SM4T26AY units undergo pre-shipment inspection (PSI). If there is an issue with SM4T26AY, 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 SM4T26AY part is unused and in its original packaging.
Return procedure for SM4T26AY:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SM4T26AY 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…
