My Inquiry
My Account
STMicroelectronics SM4T82AY
- Part No.:
- SM4T82AY
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SM4T82AY.pdf
- Description:
- TVS DIODE 70VWM 146VC SMA
- Quantity:
- Payment:
- Shipping:
Inventory:3,630
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
SM4T82AY from STMicroelectronics is an AEC-Q101-qualified unidirectional automotive TVS diode in SMA package, designed to clamp transient surges up to 113 V (VCL) at 3.5 A (IPP) under 10/1000 µs waveform, with 400 W peak pulse power rating and 70 V stand-off voltage (VRM). It protects CAN, LIN, and sensor interfaces in 12 V/24 V vehicle subsystems against ISO 7637-2 pulses (Pulse 1, 2a, 3a/b) and ISO 10605 ESD events.
For engineers reviewing the SM4T82AY datasheet, SM4T82AY pinout, SM4T82AY application, or SM4T82AY equivalent, this device delivers verified clamping performance for automotive power-line surge protection where low leakage (<0.2 µA @ 25 °C), high Tj capability (150 °C), and UL94-V0 resin compliance are mandatory.
Technical Context
The SM4T82AY employs planar silicon junction technology to achieve stable breakdown behavior across temperature (αT = 10.5 × 10−4/°C), enabling predictable VBR and VCL drift from −55 °C to +150 °C. Its unidirectional configuration provides forward conduction path only during negative transients, making it suitable for DC-biased lines like battery-supplied ECUs.
Dynamic resistance (RD = 3.75 Ω) and junction capacitance (<100 pF @ 1 V, f = 1 MHz) are optimized for fast response without signal integrity degradation on low-speed automotive buses. The device meets JEDEC-standard SMA outline and supports reflow per IPC/JEDEC J-STD-020.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VRM | 70 V - Maximum continuous reverse operating voltage before leakage exceeds 0.2 µA; sets minimum system bias margin for 24 V automotive rails. |
| VBR (min/typ/max) | 77.8 / 81.9 / 86 V @ 1 mA - Confirmed breakdown threshold ensures reliable turn-on before downstream IC damage during load-dump events. |
| VCL @ 10/1000 µs | 113 V - Clamped voltage at 3.5 A peak current; defines maximum stress imposed on protected circuitry during standardized surge test. |
| PPP | 400 W - Peak pulse power handling at Tj = 25 °C; derates linearly to ~200 W at 125 °C per Figure 3. |
| IPP @ 10/1000 µs | 3.5 A - Peak surge current supported at rated clamping voltage; validates immunity to ISO 7637-2 Pulse 1 (−150 V) and Pulse 3a (−200 V). |
| Tj max | +150 °C - Maximum junction temperature rating enables operation in engine bay or powertrain control modules without thermal derating. |
| Leakage IR | 0.2 µA @ 25 °C - Ultra-low reverse leakage preserves battery life in always-on vehicle networks (e.g., body control modules). |
Pinout & Package
SM4T82AY is housed in a standard SMA (DO-214AC) surface-mount package per JEDEC outline, with cathode band marking on one end. The package features gull-wing leads compatible with automated placement and reflow soldering per ST's recommended profile (peak 240–245 °C).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward current entry point | Connected to protected line (e.g., CAN_H); conducts during negative transients when Vanode < Vcathode − VF. |
| Cathode | Reverse-biased terminal | Connected to ground or higher-potential rail; defines clamping reference and determines unidirectional polarity. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualification | Validated for automotive under-hood use including temperature cycling, humidity, and mechanical shock per stress test requirements. |
| UL94-V0 compliant resin | Flame-retardant encapsulation prevents fire propagation in enclosed ECU housings meeting OEM safety mandates. |
| ISO 7637-2 compliance | Withstands Pulse 1 (−150 V), Pulse 2a (+112 V), Pulse 3a (−200 V), and Pulse 3b (+150 V) without parametric shift or failure. |
| Low dynamic resistance | RD = 3.75 Ω ensures minimal voltage overshoot during fast-rising transients (e.g., inductive switch-off in solenoid drivers). |
| High-temperature stability | αT = 10.5 × 10−4/°C enables accurate clamping prediction across full automotive ambient range (−40 to +125 °C). |
Applications
| Engine Control Unit (ECU) Power Input | Body Control Module (BCM) Sensor Interface |
|---|---|
Use Scenario: Protects 12 V supply input of gasoline/diesel engine ECUs against load dump (ISO 7637-2 Pulse 1) and alternator ripple-induced spikes. IC Role / Device Role / Timing Role: Unidirectional TVS placed between battery rail and input filter capacitor; clamps transients within 1 ns to limit VIN to ≤113 V. Use Value: Prevents overvoltage damage to LDOs and microcontrollers while maintaining <0.2 µA quiescent leakage to avoid battery drain during key-off. |
Use Scenario: Shields analog inputs of BCMs monitoring door lock actuators, ambient light sensors, and rain sensors from ESD and cable discharge events. IC Role / Device Role / Timing Role: Standoff-rated TVS (VRM = 70 V) mounted directly at connector entry point; suppresses ±30 kV contact/air discharges per ISO 10605. Use Value: Ensures sensor signal integrity by limiting clamping voltage to 113 V with <100 pF capacitance-no measurable distortion on 10 kHz analog signals. |
| Transmission Control Module (TCM) CAN Bus | Electric Power Steering (EPS) Motor Driver |
Use Scenario: Safeguards CAN_H/CAN_L lines in TCMs exposed to harness-induced transients during gear shifting or battery disconnect events. IC Role / Device Role / Timing Role: Dual-SMA layout with one SM4T82AY on CAN_H-to-ground and another on CAN_L-to-ground; handles bidirectional surges via separate unidirectional devices. Use Value: Maintains CAN FD communication integrity by clamping common-mode surges to <113 V while preserving <1 ns response time and <3.75 Ω dynamic impedance. |
Use Scenario: Protects H-bridge gate drivers in EPS systems from inductive kickback during motor commutation and sudden torque reversal. IC Role / Device Role / Timing Role: Mounted across motor phase terminals (e.g., PHASE_A to GND); absorbs 400 W energy bursts from 24 V supply line during PWM switching transitions. Use Value: Enables robust 150 °C junction operation in sealed EPS housings, eliminating thermal shutdown risk during sustained steering assist cycles. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar unidirectional automotive TVS applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ85A | VRM = 85 V, VCL = 125 V @ 3.2 A, PPP = 600 W, SMB package (larger footprint) | Higher stand-off voltage suits 48 V mild-hybrid systems; less optimal for 24 V rails due to reduced margin below VBR. | Select when system nominal voltage exceeds 28 V or when higher surge margin is required beyond ISO 7637-2 Pulse 1. |
| 1.5SMC82A | VRM = 70 V, VCL = 113 V @ 3.5 A, PPP = 1500 W, SMC package (3.5×3.5 mm vs SMA 2.9×4.6 mm) | Same clamping but 3.75× higher peak power; requires larger PCB area and different thermal layout. | Choose for heavy-duty commercial vehicle applications with extended ISO 7637-2 Pulse 1 duration or repeated surge exposure. |
Compared with SMBJ85A and 1.5SMC82A, SM4T82AY offers optimal balance of compact SMA footprint, precise 70 V stand-off matching 24 V automotive rails, and validated AEC-Q101 reliability-making it the preferred choice for space-constrained ECU and BCM designs requiring zero compromise on leakage or temperature stability.
Availability
SM4T82AY is available at Aetrix Electronics and suitable for engine control units, body control modules, transmission control modules, and electric power steering systems requiring stable component supply across automotive production lifecycles.
Supply support for SM4T82AY 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 discrete technologies with over 40 years of automotive-grade component development.
The SM4TY series was engineered specifically for ISO 7637-2 and ISO 10605 compliance in automotive electronics, targeting high-reliability protection of 12 V/24 V power and signal lines in harsh under-hood environments.
FAQ
What is the maximum clamping voltage of SM4T82AY under a 10/1000 µs surge?
The maximum clamping voltage (VCL) of SM4T82AY is 113 V when subjected to a 10/1000 µs waveform at 3.5 A peak current, as specified in Table 2 of DS6927 Rev 6. This value is measured at Tamb = 25 °C and remains stable up to Tj = 125 °C with temperature coefficient αT = 10.5 × 10−4/°C.
Is SM4T82AY suitable for protecting CAN FD bus lines?
Yes-SM4T82AY is appropriate for CAN FD physical layer protection due to its 113 V clamping voltage, <100 pF junction capacitance at 1 V, and sub-nanosecond response time. When used in dual configuration (one per line), it maintains signal integrity up to 5 Mbps while suppressing ISO 7637-2 transients on both CAN_H and CAN_L.
How does SM4T82AY differ from SM4T82CAY?
SM4T82AY is unidirectional (anode-to-cathode conduction only), whereas SM4T82CAY is bidirectional (symmetrical clamping for AC-coupled or floating lines). Their VRM, VBR, and VCL values are identical, but SM4T82CAY exhibits matched positive/negative breakdown and is marked "EBIY" versus "EUIY" for the AY version.
Does SM4T82AY require derating at elevated ambient temperatures?
Yes-peak pulse power must be derated linearly above 25 °C per Figure 3 in DS6927. At 100 °C ambient, PPP drops to ~280 W; at 125 °C, it falls to ~220 W. Designers must verify thermal design using Rth(j-a) curves (Figure 12) and ensure copper area under each lead meets ≥2.5 cm² for full-rated performance.
SM4T82AY 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):
- 70V
- Voltage - Breakdown (Min):
- 77.8V
- Voltage - Clamping (Max) @ Ipp:
- 146V
- Current - Peak Pulse (10/1000µs):
- 16A (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)
SM4T82AY FAQ
1.How can I place an order for SM4T82AY through Aetrix?
Please submit a Request for Quotation (RFQ) for SM4T82AY 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 SM4T82AY reliable?
The price and inventory of SM4T82AY are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SM4T82AY is usually 5 days.
3.What payment methods are accepted for SM4T82AY?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SM4T82AY transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SM4T82AY?
SM4T82AY orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SM4T82AY 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 SM4T82AY?
For technical support, including SM4T82AY datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SM4T82AY requirements.
6.How does Aetrix verify that SM4T82AY is sourced from the original manufacturer or authorized distributors?
All SM4T82AY 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 SM4T82AY meets industry standards.
7.What is the process for return or replacement of SM4T82AY?
All SM4T82AY units undergo pre-shipment inspection (PSI). If there is an issue with SM4T82AY, 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 SM4T82AY part is unused and in its original packaging.
Return procedure for SM4T82AY:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SM4T82AY 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…
