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Vishay General Semiconductor - Diodes Division SM8S28CAHM3/I
- Part No.:
- SM8S28CAHM3/I
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Category:
- TVS Diodes
- Package:
- DO-218AB
- Datasheet:
-
SM8S28CAHM3/I.pdf
- Description:
- 6600 W BI-DIRECTIONAL TVS IS DO-
- Quantity:
- Payment:
- Shipping:
Inventory:3,000
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Product details
Overview
SM8S28CAHM3/I from Vishay General Semiconductor is a bidirectional surface-mount PAR® transient voltage suppressor (TVS) designed for automotive load dump protection. It features a 31.1–34.4 V breakdown voltage (VBR), 28.0 V stand-off voltage (VWM), 45.4 V maximum clamping voltage (VC) at 145 A peak pulse current, and 6600 W peak pulse power (10/1000 μs). It operates from −55 °C to +175 °C and is AEC-Q101 qualified for under-hood automotive electronics.
For engineers reviewing the SM8S28CAHM3/I datasheet, SM8S28CAHM3/I pinout, SM8S28CAHM3/I application, or SM8S28CAHM3/I equivalent, this device is selected for high-reliability 12 V/24 V automotive power rail protection where ISO 7637-2 and ISO 16750-2 surge compliance, low leakage (<10 μA at VWM), and DO-218AC thermal performance are critical.
Technical Context
This TVS diode uses a planar silicon junction structure optimized for high-temperature stability and fast response to transients up to 10/1000 μs. Its bidirectional configuration enables symmetrical clamping without polarity constraints, and its DO-218AC package integrates a metal heatsink terminal for low RθJM (0.35 °C/W) and high surge energy handling.
The device delivers 6600 W peak pulse power with 45.4 V clamping at 145 A, validated per IEC 61000-4-5 and automotive surge standards. Its 175 °C junction rating supports placement near hot engine-control units, and its MSL Level 1 rating ensures robust reflow compatibility without moisture sensitivity concerns.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VBR (min/typ/max) | 31.1 / 32.8 / 34.4 V - Ensures reliable triggering above normal 24 V system operating voltage while avoiding false clamping during cranking transients. |
| VWM | 28.0 V - Sustains continuous reverse bias up to battery overvoltage conditions without leakage degradation. |
| VC @ IPPM | 45.4 V at 145 A (10/1000 μs) - Limits downstream IC voltage stress to safe levels during ISO 7637-2 Pulse 5a load dump events. |
| PPPM | 6600 W (10/1000 μs) - Handles worst-case automotive load dump energy without thermal runaway or parametric shift. |
| TJ max | +175 °C - Enables direct mounting on high-temperature PCB zones near ECUs or power modules without derating. |
| Leakage @ VWM | <10 μA at 25 °C - Minimizes standby current draw in always-on vehicle networks (e.g., CAN bus wake-up circuits). |
| AEC-Q101 | Qualified - Meets stress test requirements for automotive-grade reliability including temperature cycling, HTRB, and ESD. |
Pinout & Package
Package: DO-218AC - Surface-mount case with integrated metal heatsink terminal (Lead 2), matte tin-plated leads, halogen-free molding compound (UL 94 V-0), and no cathode band (bidirectional polarity).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Lead 1 | Anode connection | Primary current entry point during positive transients; soldered to protected line (e.g., battery feed). |
| Lead 2 / Metal Heatsink | Cathode connection & thermal path | Provides low-inductance return path and direct thermal conduction to PCB copper pour or heatsink plane. |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional clamping | Eliminates need for polarity-aware layout; protects against both positive and negative transients on shared power rails. |
| 175 °C junction rating | Supports operation adjacent to power MOSFETs or DC/DC converters in engine control modules without thermal derating. |
| ISO 7637-2 & ISO 16750-2 compliance | Validated for automotive load dump (Pulse 5a), jump start, and alternator ripple immunity per OEM requirements. |
| MSL Level 1 (245 °C peak) | Enables single-pass lead-free reflow without baking or special handling, reducing manufacturing cost and risk. |
| RθJM = 0.35 °C/W | Enables >80% of rated power dissipation via PCB copper, reducing need for external heatsinks in space-constrained modules. |
Applications
| Automotive Load Dump Protection | Engine Control Unit (ECU) Power Input |
|---|---|
Use Scenario: Protecting 24 V commercial vehicle ECUs from alternator load dump surges exceeding 120 V. IC Role / Device Role / Timing Role: Primary clamping device placed directly at power entry point before DC/DC converter input. Use Value: Clamps transients to ≤45.4 V within nanoseconds, preventing damage to downstream 40 V-rated buck controllers and microcontrollers. |
Use Scenario: Safeguarding power supply inputs of diesel engine control modules exposed to repeated cranking and vibration. IC Role / Device Role / Timing Role: Standoff protector maintaining <10 μA leakage during 28 V nominal operation while responding to sub-100 ns spikes. Use Value: Enables AEC-Q101-compliant design without additional filtering, reducing BOM count and board area by 30% vs. RC+TVS solutions. |
| Body Control Module (BCM) Power Rail | ADAS Camera Power Supply |
Use Scenario: Securing 12 V supply to BCMs managing lighting, door locks, and HVAC in passenger vehicles. IC Role / Device Role / Timing Role: Bidirectional TVS absorbing both load dump and inductive kickback from relay coils and motors. Use Value: Eliminates need for separate forward/reverse protection diodes, simplifying layout and ensuring symmetric clamping behavior. |
Use Scenario: Shielding 5 V/3.3 V camera module power inputs from coupled transients in adjacent high-current wiring harnesses. IC Role / Device Role / Timing Role: Secondary-level protection after primary DC/DC, leveraging low capacitance and fast response. Use Value: Maintains signal integrity in high-speed image sensors by limiting clamping overshoot to <5 V above rail, avoiding reset or latch-up. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ28A-E3/5A (Vishay) | DO-214AC package; 400 W PPPM; 45.7 V VC at 8.2 A; lower surge rating and thermal mass. | Rated for consumer/industrial use only; not AEC-Q101 qualified or ISO 7637-2 validated. | Select when cost-sensitive non-automotive designs require basic 28 V clamping with minimal footprint. |
| TPSMD28CA (Texas Instruments) | DO-218AC package; 6600 W PPPM; 45.4 V VC at 145 A; identical clamping but 150 °C TJ max and no MSL Level 1 rating. | Limited to under-hood ambient ≤125 °C; requires pre-bake for lead-free reflow due to MSL Level 3 classification. | Choose if existing TI-design ecosystems prioritize vendor consolidation, accepting reduced thermal margin and reflow complexity. |
Compared with SMAJ28A-E3/5A and TPSMD28CA, SM8S28CAHM3/I uniquely combines AEC-Q101 qualification, 175 °C operation, MSL Level 1 process compatibility, and full ISO 7637-2 validation-making it the only option qualified for next-generation 24 V commercial vehicle power distribution units without design compromise.
Availability
SM8S28CAHM3/I is available at Aetrix Electronics and suitable for automotive load dump protection, engine control unit (ECU) power input hardening, and body control module (BCM) power rail stabilization requiring stable component supply across extended production lifecycles.
Supply support for SM8S28CAHM3/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 is engineered specifically for automotive-grade transient suppression, targeting 12 V/24 V power systems requiring AEC-Q101 qualification, high-temperature resilience, and standardized surge compliance.
FAQ
What is the maximum clamping voltage of SM8S28CAHM3/I under standard test conditions?
The SM8S28CAHM3/I has a maximum clamping voltage (VC) of 45.4 V when subjected to a 10/1000 μs waveform at its rated peak pulse current of 145 A. This value is measured per Figure 4 in the Vishay datasheet (Doc. #98229) and defines the upper voltage limit imposed on protected circuitry during worst-case transients. The SM8S28CAHM3/I maintains this clamping performance across its full operating temperature range.
Is SM8S28CAHM3/I qualified for automotive applications?
Yes, SM8S28CAHM3/I is AEC-Q101 qualified and meets ISO 7637-2 and ISO 16750-2 surge test requirements for automotive use. Its DO-218AC package carries the HM3 suffix indicating halogen-free, RoHS-compliant, and whisker-tested construction. The SM8S28CAHM3/I is explicitly rated for junction temperatures up to +175 °C, making it suitable for under-hood deployment in engine control units and battery management systems.
What does the "HM3/I" suffix mean in SM8S28CAHM3/I?
In SM8S28CAHM3/I, "H" denotes AEC-Q101 qualification, "M3" specifies halogen-free, RoHS-compliant, and Pb-free termination meeting JESD 201 Class 2 whisker resistance, and "I" indicates packaging in 13-inch plastic tape and reel with anode orientation toward sprocket holes. This full suffix confirms the SM8S28CAHM3/I meets automotive-grade material, reliability, and assembly requirements per Vishay's ordering nomenclature.
How does SM8S28CAHM3/I compare to SM8S28A in terms of polarity and application?
SM8S28CAHM3/I is bidirectional (denoted by "CA"), enabling symmetrical clamping for both positive and negative transients on AC-coupled or floating lines, whereas SM8S28A is unidirectional ("A") and requires correct polarity orientation. The SM8S28CAHM3/I is preferred for automotive power rails where reverse battery connection or bipolar noise is possible, eliminating layout errors and field failures associated with unidirectional part misplacement.
What thermal performance can be expected from SM8S28CAHM3/I on a standard FR-4 PCB?
When mounted on a standard FR-4 PCB with minimum recommended pad layout, SM8S28CAHM3/I exhibits a junction-to-ambient thermal resistance (RθJA) of 55 °C/W and a superior junction-to-mount resistance (RθJM) of 0.35 °C/W. This allows >8 W steady-state power dissipation with proper copper pour, and enables the SM8S28CAHM3/I to sustain repeated 6600 W surges without exceeding 175 °C junction temperature under typical automotive ambient conditions.
SM8S28CAHM3/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):
- 28V
- Voltage - Breakdown (Min):
- 31.1V
- Voltage - Clamping (Max) @ Ipp:
- 45.4V
- Current - Peak Pulse (10/1000µs):
- 145A
- 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
SM8S28CAHM3/I FAQ
1.How can I place an order for SM8S28CAHM3/I through Aetrix?
Please submit a Request for Quotation (RFQ) for SM8S28CAHM3/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 SM8S28CAHM3/I reliable?
The price and inventory of SM8S28CAHM3/I are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SM8S28CAHM3/I is usually 5 days.
3.What payment methods are accepted for SM8S28CAHM3/I?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SM8S28CAHM3/I transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SM8S28CAHM3/I?
SM8S28CAHM3/I orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SM8S28CAHM3/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 SM8S28CAHM3/I?
For technical support, including SM8S28CAHM3/I datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SM8S28CAHM3/I requirements.
6.How does Aetrix verify that SM8S28CAHM3/I is sourced from the original manufacturer or authorized distributors?
All SM8S28CAHM3/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 SM8S28CAHM3/I meets industry standards.
7.What is the process for return or replacement of SM8S28CAHM3/I?
All SM8S28CAHM3/I units undergo pre-shipment inspection (PSI). If there is an issue with SM8S28CAHM3/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 SM8S28CAHM3/I part is unused and in its original packaging.
Return procedure for SM8S28CAHM3/I:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SM8S28CAHM3/I Tags
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