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Vishay General Semiconductor - Diodes Division SM8S40ATHE3/I
- Part No.:
- SM8S40ATHE3/I
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Category:
- TVS Diodes
- Package:
- DO-218AC
- Datasheet:
-
SM8S40ATHE3/I.pdf
- Description:
- TVS DIODE 40VWM 64.5VC DO218AC
- Quantity:
- Payment:
- Shipping:
Inventory:8,550
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Product details
Overview
SM8S40ATHE3/I from Vishay General Semiconductor is a unidirectional surface-mount PAR® transient voltage suppressor (TVS) designed for automotive load dump protection in high-reliability 12 V/24 V systems. It features a 44.4–49.1 V breakdown voltage (VBR), 6600 W peak pulse power (10/1000 μs), 102 A clamping current (IPPM), 64.5 V maximum clamping voltage (VC), and AEC-Q101 qualification for under-hood applications.
For engineers reviewing the SM8S40ATHE3/I datasheet, SM8S40ATHE3/I pinout, SM8S40ATHE3/I application, or SM8S40ATHE3/I equivalent, key selection criteria include its DO-218AC package thermal performance (RθJC = 0.90 °C/W), 175 °C junction rating, unidirectional polarity with heatsink-as-anode configuration, and ISO7637-2 compliance for automotive transients.
Technical Context
This TVS diode operates as a clamping device in parallel with sensitive electronics to divert surge energy during load dump events. Its passivated anisotropic rectifier structure enables low leakage (<10 μA at VWM = 40 V) and low forward voltage drop (≤1.8 V at 100 A), while sustaining 700 A non-repetitive forward surge current (IFSM) and 5200 W power under 10/10,000 μs waveform.
Thermal design relies on direct case-to-heatsink conduction via the metal anode tab; derating begins above TA = 25 °C per the published power derating curve. The device is not intended for new designs-Vishay explicitly recommends SM8S40AHM3 as the replacement series due to enhanced reliability and updated qualification.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VBR (min/typ/max) | 44.4 / 46.8 / 49.1 V - defines minimum voltage at which clamping initiates reliably under 5 mA test current |
| VWM | 40 V - maximum continuous reverse operating voltage before significant leakage begins |
| VC @ IPPM | 64.5 V - clamped voltage seen by protected circuit during 102 A 10/1000 μs surge |
| PPPM (10/1000 μs) | 6600 W - peak transient power handling capacity critical for ISO7637-2 load dump survival |
| RθJC | 0.90 °C/W - enables efficient heat transfer from junction to heatsink, supporting 175 °C TJ operation |
| TJ max | 175 °C - qualified junction temperature ceiling for under-hood automotive environments |
| Polarity | Unidirectional - anode connected to heatsink, cathode to protected line; blocks reverse surge only |
Pinout & Package
Package: DO-218AC - molded surface-mount case with integral metal heatsink tab (anode), RoHS-compliant matte tin-plated leads, UL 94 V-0 rated compound, MSL Level 1 (245 °C reflow).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode (Heatsink Tab) | Current return path and thermal interface | Must be soldered to large copper pour or external heatsink; electrically and thermally critical node |
| Cathode (Lead 1) | Surge input terminal | Connected to protected line (e.g., battery rail); carries full transient current into anode |
Key Features
| Feature | Design Value |
|---|---|
| Junction passivation optimized design | Enables stable VBR drift <0.092 %/°C and <10 μA leakage at 175 °C, ensuring long-term reliability |
| TJ = 175 °C capability | Validated for continuous operation in engine compartment environments without derating penalties |
| AEC-Q101 qualification | Meets stress testing requirements for automotive electronic components including HTGB, HTRB, and TC |
| ISO7637-2 compliance | Rated for load dump pulses up to 5200 W (10/10,000 μs), matching OEM vehicle electrical system specs |
| DO-218AC mechanical robustness | Withstands 700 A surge without bond wire failure; metal tab provides low-inductance, low-resistance path |
Applications
| Automotive Load Dump Protection | Industrial Power Supply Input Protection |
|---|---|
Use Scenario: Protecting ECUs, body control modules, and infotainment systems from 12 V/24 V battery line transients during alternator load dump. IC Role / Device Role / Timing Role: Parallel-connected clamping TVS absorbing >6 kW surges within microseconds to hold downstream voltage below 65 V. Use Value: Prevents latch-up or destruction of 40 V-rated DC-DC converters and microcontrollers during ISO7637-2 Pulse 5a events. | Use Scenario: Safeguarding industrial PLC power inputs against switching transients from solenoids, contactors, and motor drives. IC Role / Device Role / Timing Role: Standoff-rated TVS placed at main AC/DC or DC/DC converter input to clamp fast-rising spikes before bulk capacitance. Use Value: Maintains VWM = 40 V margin over 36 V nominal industrial rails while surviving repetitive 100 A surges. |
| Telecom Power Feeding Protection | Renewable Energy Charge Controller Protection |
Use Scenario: Securing PoE midspan injectors and remote radio units powered over long cable runs subject to lightning-induced surges. IC Role / Device Role / Timing Role: Primary-level TVS on 48 V DC feed lines, coordinated with secondary GDT or MOV stages. Use Value: Clamps to 64.5 V within 1 ns, limiting stress on 60 V-rated MOSFETs and gate drivers in power management ICs. | Use Scenario: Shielding solar charge controllers from voltage reversals and inductive kickback when disconnecting PV arrays or batteries. IC Role / Device Role / Timing Role: Unidirectional TVS across battery terminals to absorb reverse-energy surges during rapid disconnection. Use Value: Withstands 700 A IFSM and maintains <10 μA leakage at 40 V, preserving battery standby efficiency. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SM8S40AHM3 | Same VBR, VC, and package; improved whisker resistance (JESD201 Class 2), updated AEC-Q101 test report, and active production status | Drop-in replacement for new designs; supports longer product lifecycle and extended automotive qualification documentation | Select SM8S40AHM3 for all new designs-Vishay explicitly marks SM8S40ATHE3/I as Not For New Designs |
| SMAJ40A | Lower PPPM (400 W vs. 6600 W), DO-214AC package, no AEC-Q101 qualification, RθJC >3.0 °C/W | Limited to low-energy consumer or non-automotive applications; cannot meet ISO7637-2 load dump requirements | Only consider SMAJ40A if surge energy is <500 W and automotive qualification is not required |
Compared with SM8S40ATHE3/I, SM8S40AHM3 offers identical electrical performance with enhanced reliability and active support, while SMAJ40A provides basic clamping at significantly lower surge capacity and thermal capability-making it unsuitable for automotive or high-energy industrial use.
Availability
SM8S40ATHE3/I is available at Aetrix Electronics and suitable for automotive ECU protection, industrial PLC input stages, and telecom power feeding circuits requiring stable component supply and legacy design continuity.
Supply support for SM8S40ATHE3/I 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
Vishay General Semiconductor is a global leader in discrete semiconductors, specializing in diodes, rectifiers, optoelectronics, and passive components with emphasis on high-reliability and automotive-grade solutions.
The SM8SxxAT family was engineered specifically for automotive load dump protection, combining high-power surge handling, extreme temperature resilience, and AEC-Q101 validation in a thermally optimized DO-218AC package.
FAQ
Is SM8S40ATHE3/I AEC-Q101 qualified?
Yes, SM8S40ATHE3/I is AEC-Q101 qualified and explicitly listed as such in Vishay's official documentation. This qualification covers stress tests including high-temperature reverse bias (HTRB), high-temperature gate bias (HTGB), and temperature cycling (TC), confirming suitability for automotive under-hood applications where junction temperatures reach 175 °C. The HE3 suffix denotes RoHS compliance and JESD201 Class 2 whisker resistance.
What is the clamping voltage of SM8S40ATHE3/I at its rated peak pulse current?
The maximum clamping voltage (VC) of SM8S40ATHE3/I is 64.5 V at IPPM = 102 A under the standard 10/1000 μs waveform. This value is guaranteed across the full operating temperature range and ensures protected downstream components-such as 60 V-rated DC-DC controllers-remain within safe voltage limits during worst-case transients. VC is measured with specified test conditions per JEDEC standards.
Why does Vishay mark SM8S40ATHE3/I as "Not For New Designs"?
Vishay designates SM8S40ATHE3/I as "Not For New Designs" because the newer SM8S40AHM3 variant supersedes it with improved manufacturing controls, updated AEC-Q101 test reports, and enhanced whisker resistance (JESD201 Class 2). While SM8S40ATHE3/I remains fully functional and supported for existing designs, Vishay recommends SM8S40AHM3 for all new projects to ensure long-term supply continuity and access to latest reliability data.
Can SM8S40ATHE3/I be used in bidirectional configurations?
No, SM8S40ATHE3/I is unidirectional only, with polarity defined as anode = heatsink tab and cathode = lead 1. It conducts and clamps only in reverse-biased mode (cathode positive relative to anode). Bidirectional protection requires either two devices in series opposition or a dedicated bidirectional TVS such as the SMBJ40CA. Attempting to use SM8S40ATHE3/I in forward conduction for surge suppression will result in permanent damage.
What is the thermal resistance from junction to case (RθJC) for SM8S40ATHE3/I?
The typical thermal resistance from junction to case (RθJC) for SM8S40ATHE3/I is 0.90 °C/W, measured under standard test conditions with the anode tab fully soldered to a large copper heatsink area. This low value enables effective heat dissipation during high-energy transients and supports continuous operation at TJ = 175 °C when mounted correctly. PCB layout must allocate ≥200 mm² of 2 oz copper directly under the heatsink tab.
SM8S40ATHE3/I Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Package/Case:
- DO-218AC
- Series:
- PAR®
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Type:
- Zener
- Unidirectional Channels:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 40V
- Voltage - Breakdown (Min):
- 44.4V
- Voltage - Clamping (Max) @ Ipp:
- 64.5V
- Current - Peak Pulse (10/1000µs):
- 102A
- Power - Peak Pulse:
- 6600W (6.6kW)
- Power Line Protection:
- No
- Applications:
- -
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 175°C (TJ)
- Grade:
- Automotive
- Qualification:
- AEC-Q101
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-218AC
SM8S40ATHE3/I FAQ
1.How can I place an order for SM8S40ATHE3/I through Aetrix?
Please submit a Request for Quotation (RFQ) for SM8S40ATHE3/I 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 SM8S40ATHE3/I reliable?
The price and inventory of SM8S40ATHE3/I are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SM8S40ATHE3/I is usually 5 days.
3.What payment methods are accepted for SM8S40ATHE3/I?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SM8S40ATHE3/I transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SM8S40ATHE3/I?
SM8S40ATHE3/I orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SM8S40ATHE3/I 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 SM8S40ATHE3/I?
For technical support, including SM8S40ATHE3/I datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SM8S40ATHE3/I requirements.
6.How does Aetrix verify that SM8S40ATHE3/I is sourced from the original manufacturer or authorized distributors?
All SM8S40ATHE3/I 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 SM8S40ATHE3/I meets industry standards.
7.What is the process for return or replacement of SM8S40ATHE3/I?
All SM8S40ATHE3/I units undergo pre-shipment inspection (PSI). If there is an issue with SM8S40ATHE3/I, 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 SM8S40ATHE3/I part is unused and in its original packaging.
Return procedure for SM8S40ATHE3/I:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SM8S40ATHE3/I Tags
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