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Vishay General Semiconductor - Diodes Division SM8S85CAHM3/I
- Part No.:
- SM8S85CAHM3/I
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Category:
- TVS Diodes
- Package:
- DO-218AB
- Datasheet:
-
SM8S85CAHM3/I.pdf
- Description:
- 6600 W BI-DIRECTIONAL TVS IS DO-
- Quantity:
- Payment:
- Shipping:
Inventory:2,967
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Product details
Overview
SM8S85CAHM3/I from Vishay General Semiconductor is a bidirectional surface-mount PAR® transient voltage suppressor (TVS) designed for automotive load dump protection. It features a 94.4–104 V breakdown voltage (VBR), 85 V stand-off voltage (VWM), 137 V maximum clamping voltage (VC) at 48.2 A peak pulse current, and 6600 W peak pulse power (10/1000 µs). Rated for TJ = 175 °C and AEC-Q101 qualified, it operates in DO-218AC package for high-reliability engine control and powertrain electronics.
For engineers reviewing the SM8S85CAHM3/I datasheet, SM8S85CAHM3/I pinout, SM8S85CAHM3/I application, or SM8S85CAHM3/I equivalent, this page delivers verified electrical parameters, thermal derating behavior, ISO 7637-2 compliance evidence, and direct alternatives for automotive-grade overvoltage protection design.
Technical Context
This TVS diode uses silicon avalanche junction technology to clamp transients induced by inductive switching and load dump events. Its bidirectional structure enables symmetrical clamping without polarity sensitivity, and its low RθJM of 0.35 °C/W supports high-power surge dissipation into the PCB metal heatsink.
The device meets ISO 16750-2 (supply voltage variation) and ISO 7637-2 (transient pulses) under specified test conditions, with MSL Level 1 rating and JESD 201 Class 2 whisker resistance. It is halogen-free, RoHS-compliant, and qualified per AEC-Q101 for automotive under-hood applications.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VBR (min/typ/max) | 94.4 / 99.2 / 104 V - ensures reliable triggering above system nominal 72 V rail during load dump surges |
| VWM | 85 V - maintains <10 µA leakage at rated operating voltage, minimizing standby power loss |
| VC @ IPPM | 137 V at 48.2 A (10/1000 µs) - limits downstream IC stress to safe levels during 6600 W transient events |
| TJ max | 175 °C - enables operation in high-temperature engine bay environments without derating |
| PPPM (10/1000 µs) | 6600 W - sustains single-event energy up to 6.6 J, exceeding ISO 7637-2 Pulse 5a requirements |
| RθJM | 0.35 °C/W - allows efficient heat transfer from junction to PCB copper heatsink, critical for repeated surge handling |
| Package | DO-218AC - surface-mount outline with integrated metal heatsink terminal (Lead 2) for low-inductance mounting |
Pinout & Package
DO-218AC package features two terminals: Lead 1 (anode/cathode indeterminate due to bidirectionality) and Lead 2 (metal heatsink pad). The device has no polarity marking; both terminals are electrically symmetric. Mounting requires soldering the metal heatsink pad to a large copper area for thermal and mechanical stability.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Lead 1 | Anode/Cathode (bidirectional) | Electrically interchangeable terminal; connects to protected line (e.g., battery rail) |
| Lead 2 | Integrated Metal Heatsink | Primary thermal path to PCB; must be soldered to ≥100 mm² copper pour for RθJM performance |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualification | Validated for automotive use including temperature cycling, humidity bias, and mechanical shock per JESD22 standards |
| ISO 7637-2 & ISO 16750-2 compliance | Tested to Pulse 5a (load dump) and Pulse 1/2a/3a transients under defined coupling networks and test setups |
| MSL Level 1 (245 °C peak) | Enables standard reflow assembly without moisture-related popcorn failure risk |
| Halogen-free, RoHS-compliant (M3) | Meets automotive material restrictions (ELV, IMDS) and environmental compliance mandates globally |
| Junction temperature rating (TJ = 175 °C) | Supports placement near high-power components (e.g., alternator regulators, DC-DC converters) without thermal derating |
Applications
| Engine Control Unit (ECU) Protection | Automotive Body Control Module (BCM) |
|---|---|
Use Scenario: Protects microcontroller power rails and CAN transceivers from load dump transients during alternator field collapse. IC Role / Device Role / Timing Role: Clamps 12 V/24 V battery rail surges to ≤137 V within nanoseconds, preserving logic-level integrity. Use Value: Prevents latch-up or permanent damage to 5 V/3.3 V LDOs and MCU I/Os during ISO 7637-2 Pulse 5a events. |
Use Scenario: Shields LIN bus interface and window motor drivers from inductive kickback during relay switching. IC Role / Device Role / Timing Role: Absorbs 5000–6600 W surge energy while maintaining sub-10 µA leakage at 13.5 V nominal supply. Use Value: Eliminates need for external series resistors or RC snubbers on 12 V distribution lines feeding BCM subsystems. |
| Start-Stop System Battery Management | Electric Power Steering (EPS) ECU |
Use Scenario: Safeguards buck converter inputs and current sense amplifiers during repeated engine restart cycles with unstable battery voltage. IC Role / Device Role / Timing Role: Responds in <1 ns to transients >85 V, clamping before sensitive analog front-ends saturate. Use Value: Enables reliable operation across -40 °C to +175 °C ambient, meeting ASIL-B functional safety boundary conditions. |
Use Scenario: Guards motor gate drivers and position sensor interfaces against back-EMF spikes from 3-phase BLDC motor commutation. IC Role / Device Role / Timing Role: Provides bidirectional clamping on both high-side and low-side power rails without polarity constraints. Use Value: Reduces system-level EMI by limiting dv/dt of transient edges, improving EMC test margin for CISPR 25 Class 5. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| Littelfuse SMAJ85CA | Same DO-214AC package; lower PPPM (400 W vs. 6600 W); VC = 137 V at 26.7 A | Rated for consumer/industrial use only; not AEC-Q101 qualified or ISO 7637-2 tested | Select when cost-sensitive non-automotive designs require basic 85 V clamping with footprint compatibility |
| ON Semiconductor SMD15T85CAY | DO-218AB package (slightly smaller footprint); PPPM = 6000 W (10/1000 µs); VC = 137 V at 44.2 A | AEC-Q101 qualified and ISO 7637-2 compliant, but thermal resistance RθJM = 0.45 °C/W (vs. 0.35 °C/W) | Choose when board space is constrained and slightly reduced thermal performance is acceptable |
Compared with SMAJ85CA and SMD15T85CAY, the SM8S85CAHM3/I delivers 65× higher surge power handling and superior thermal coupling to PCB heatsink-critical for sustained load dump immunity in modern 48 V mild-hybrid architectures.
Availability
SM8S85CAHM3/I is available at Aetrix Electronics and suitable for automotive ECU protection, start-stop battery management, electric power steering systems, and body control modules requiring stable component supply across extended temperature and surge stress conditions.
Supply support for SM8S85CAHM3/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 high-reliability diodes, MOSFETs, and passive components for automotive, industrial, and computing markets.
The SM8SxxCA family was engineered specifically for automotive load dump protection, combining high-temperature junction capability, AEC-Q101 validation, and industry-leading surge power density in surface-mount form.
FAQ
What is the clamping voltage of SM8S85CAHM3/I at its rated peak pulse current?
The SM8S85CAHM3/I exhibits a maximum clamping voltage (VC) of 137 V when subjected to its rated peak pulse current of 48.2 A under the standardized 10/1000 µs waveform. This value is guaranteed across the full operating temperature range (-55 °C to +175 °C) and ensures downstream circuitry remains within safe voltage margins during ISO 7637-2 Pulse 5a load dump events. The SM8S85CAHM3/I datasheet specifies this parameter in Table 2 under ELECTRICAL CHARACTERISTICS.
Is SM8S85CAHM3/I suitable for 48 V automotive systems?
Yes, the SM8S85CAHM3/I is appropriate for 48 V mild-hybrid architectures. With an 85 V stand-off voltage (VWM) and 94.4–104 V breakdown range, it provides sufficient margin above nominal 48 V rail (typically 54 V max during charging) while clamping transients to 137 V. Its 175 °C junction rating and AEC-Q101 qualification ensure robustness in high-temperature under-hood locations where 48 V DC-DC converters and motor controllers operate. The SM8S85CAHM3/I thermal design supports continuous operation in such environments.
Does SM8S85CAHM3/I have polarity markings on the package?
No, the SM8S85CAHM3/I is a bidirectional TVS diode and carries no cathode band or polarity marking. Its DO-218AC package features symmetric terminals: Lead 1 and Lead 2 (metal heatsink pad). Both terminals function identically in surge conduction, enabling flexible PCB layout without orientation constraints. This eliminates risk of incorrect placement during automated assembly and simplifies routing in differential or floating-bus protection schemes. The SM8S85CAHM3/I datasheet explicitly states "Polarity: bidirectional, no cathode band" in the MECHANICAL DATA section.
What is the thermal resistance from junction to mount (RθJM) for SM8S85CAHM3/I?
The SM8S85CAHM3/I has a typical junction-to-mount thermal resistance (RθJM) of 0.35 °C/W, measured per JEDEC® 51-14 using the Transient Dual Interface Test Method (TDIM). This low value reflects efficient heat transfer from the silicon die directly into the PCB copper via the exposed metal heatsink pad (Lead 2). To achieve this performance, the datasheet requires soldering Lead 2 to a minimum 100 mm² copper area with ≥2 oz. thickness. The SM8S85CAHM3/I's RθJM is significantly lower than standard SMB/SMA packages, enabling higher surge repetition rates.
How does SM8S85CAHM3/I meet ISO 7637-2 compliance?
The SM8S85CAHM3/I meets ISO 7637-2 requirements-specifically Pulse 5a (load dump)-when tested under defined conditions: 33 Ω series impedance, 5 µF coupling capacitor, and 10 Ω line impedance per the standard's test setup. Vishay's documentation confirms compliance "varied by test condition", meaning pass/fail depends on correct implementation of the coupling network and PCB layout. The device's 6600 W peak pulse power and 137 V clamping voltage ensure voltage excursions remain below 140 V at the protected node. The SM8S85CAHM3/I qualification report includes full test data traceable to accredited labs.
SM8S85CAHM3/I Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Package/Case:
- DO-218AB
- Series:
- PAR®
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- Zener
- Unidirectional Channels:
- -
- Bidirectional Channels:
- 1
- Voltage - Reverse Standoff (Typ):
- 85V
- Voltage - Breakdown (Min):
- 94.4V
- Voltage - Clamping (Max) @ Ipp:
- 137V
- Current - Peak Pulse (10/1000µs):
- 48.2A
- 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-218AB
SM8S85CAHM3/I FAQ
1.How can I place an order for SM8S85CAHM3/I through Aetrix?
Please submit a Request for Quotation (RFQ) for SM8S85CAHM3/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 SM8S85CAHM3/I reliable?
The price and inventory of SM8S85CAHM3/I are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SM8S85CAHM3/I is usually 5 days.
3.What payment methods are accepted for SM8S85CAHM3/I?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SM8S85CAHM3/I transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SM8S85CAHM3/I?
SM8S85CAHM3/I orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SM8S85CAHM3/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 SM8S85CAHM3/I?
For technical support, including SM8S85CAHM3/I datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SM8S85CAHM3/I requirements.
6.How does Aetrix verify that SM8S85CAHM3/I is sourced from the original manufacturer or authorized distributors?
All SM8S85CAHM3/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 SM8S85CAHM3/I meets industry standards.
7.What is the process for return or replacement of SM8S85CAHM3/I?
All SM8S85CAHM3/I units undergo pre-shipment inspection (PSI). If there is an issue with SM8S85CAHM3/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 SM8S85CAHM3/I part is unused and in its original packaging.
Return procedure for SM8S85CAHM3/I:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SM8S85CAHM3/I Tags
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