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Vishay General Semiconductor - Diodes Division SM8S78CAHM3/I
- Part No.:
- SM8S78CAHM3/I
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Category:
- TVS Diodes
- Package:
- DO-218AB
- Datasheet:
-
SM8S78CAHM3/I.pdf
- Description:
- 6600 W BI-DIRECTIONAL TVS IS DO-
- Quantity:
- Payment:
- Shipping:
Inventory:2,980
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Product details
Overview
SM8S78CAHM3/I from Vishay General Semiconductor is a bidirectional surface-mount PAR® transient voltage suppressor (TVS) designed for automotive load dump protection in 12 V/24 V systems. It features a 78 V stand-off voltage (VWM), 86.7–95.8 V breakdown range (VBR), 126 V maximum clamping voltage (VC) at 52.4 A peak pulse current, and 6600 W peak pulse power (10/1000 μs). Its DO-218AC package supports high-reliability under TJ = 175 °C operation and meets AEC-Q101 qualification.
For engineers reviewing the SM8S78CAHM3/I datasheet, SM8S78CAHM3/I pinout, SM8S78CAHM3/I application, or SM8S78CAHM3/I equivalent, key selection criteria include clamping performance under ISO 7637-2 Load Dump Pulse 5a, thermal resistance (RθJM = 0.35 °C/W), bidirectional surge handling up to 52.4 A, and halogen-free, MSL Level 1 compliant packaging for automotive PCB assembly.
Technical Context
This TVS diode operates as a parallel-connected overvoltage clamp, responding within nanoseconds to transients induced by inductive switching or alternator load dump events. Its silicon avalanche structure delivers precise breakdown tolerance (±5 %) and low leakage (<10 μA at VWM, <15 μA at TJ = 175 °C), enabling stable protection without system interference during normal operation.
The DO-218AC case integrates a metal heatsink terminal (Lead 2) directly bonded to the die, achieving ultra-low junction-to-mount thermal resistance (0.35 °C/W) - critical for sustained energy dissipation in engine bay environments. It is rated for non-repetitive 10/1000 μs surges up to 6600 W and 10/10,000 μs surges up to 5200 W, per ISO 16750-2 Category III/IV test conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 78.0 V - Maximum continuous reverse operating voltage before clamping begins; defines safe system bus margin in 24 V automotive networks. |
| VBR (min/typ/max) | 86.7 / 91.3 / 95.8 V - Breakdown onset range at 5 mA test current; ±5 % tolerance ensures predictable turn-on across temperature and lot variation. |
| VC @ IPPM | 126 V at 52.4 A - Clamped voltage during 10/1000 μs surge; limits downstream IC stress below 130 V threshold for most 24 V power management ICs. |
| PPPM (10/1000 μs) | 6600 W - Peak pulse power handling; enables single-device protection against ISO 7637-2 Pulse 5a (12 V system: 300 V/10 Ω, 400 ms). |
| TJ max | 175 °C - Maximum junction temperature rating; supports under-hood placement with no derating required up to ambient +125 °C. |
| RθJM | 0.35 °C/W - Junction-to-mount thermal resistance; allows direct thermal coupling to PCB copper pour or chassis for passive cooling. |
| Leakage @ VWM | <10 μA at 25 °C, <15 μA at 175 °C - Ultra-low reverse current preserves battery life and avoids false triggering in always-on circuits. |
Pinout & Package
Package: DO-218AC - Surface-mount, bidirectional TVS with isolated anode/cathode terminals and integrated metal heatsink tab (Lead 2). Meets UL 94 V-0, JESD 201 Class 2 whisker resistance, and MSL Level 1 (245 °C peak reflow).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Lead 1 | Anode (cathode for unidirectional interpretation) | Standard signal-side connection; polarity-agnostic due to bidirectional symmetry; solderable per J-STD-002. |
| Lead 2 / Metal Heatsink | Thermal and electrical return path | Directly bonded to die substrate; must be connected to large copper area or chassis ground for optimal thermal performance and surge current return. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive-grade reliability including HTOL, TC, HTRB, and ESD testing - required for powertrain and body control module deployment. |
| Bidirectional operation | No cathode band marking; symmetric clamping for both positive and negative transients - eliminates orientation errors during automated placement. |
| ISO 7637-2 & ISO 16750-2 compliance | Tested to Pulse 5a (load dump) and Pulse 1/2a/3a (switching transients); enables drop-in integration into OEM-compliant ECU designs. |
| Halogen-free, RoHS-compliant (M3) | Meets global environmental regulations and JEDEC J-STD-020 reflow profile (245 °C peak); supports lead-free manufacturing without compromise. |
| Low RθJM (0.35 °C/W) | Enables >80 % of rated PPPM to be dissipated without active cooling - reduces need for oversized heatsinks or derating in compact modules. |
Applications
| Engine Control Unit (ECU) Power Input | Body Control Module (BCM) CAN Bus Protection |
|---|---|
Use Scenario: Protects 24 V supply rail of diesel/gasoline engine ECUs against alternator load dump spikes (up to 300 V, 400 ms). IC Role / Device Role / Timing Role: Parallel-connected transient clamp placed upstream of DC/DC converter input; responds in <1 ns to limit voltage excursion. Use Value: Maintains VIN < 130 V during Pulse 5a, preventing latch-up or destruction of buck controller ICs such as LM5143A or MPQ4333. |
Use Scenario: Shields high-speed CAN FD transceivers (e.g., TJA1044T/3) from coupled transients on vehicle battery lines routed near CAN harnesses. IC Role / Device Role / Timing Role: Bidirectional shunt device on VCC rail feeding transceiver; clamps common-mode surges without disrupting 5 Mbps data integrity. Use Value: Limits rail overshoot to ≤126 V during ISO 7637-2 Pulse 1 (inductive switch-off), preserving transceiver fault immunity and EMC robustness. |
| ADAS Camera Power Supply | Electric Power Steering (EPS) Motor Driver |
Use Scenario: Secures 12 V input to image sensor SoCs (e.g., S900 or IMX500) in front-facing ADAS cameras exposed to engine bay thermal and electrical stress. IC Role / Device Role / Timing Role: Primary overvoltage guard on camera module's main power rail; coordinates with secondary ceramic capacitor filtering. Use Value: Withstands repeated 10/1000 μs surges up to 6600 W while maintaining leakage <10 μA - avoids dark current drift or sensor reset during operation. |
Use Scenario: Protects gate driver ICs (e.g., DRV8305) and MOSFET half-bridges in EPS motor control units subjected to load dump and back-EMF reversal. IC Role / Device Role / Timing Role: High-energy clamp on 12 V auxiliary supply feeding driver logic and bootstrap circuitry. Use Value: Delivers 52.4 A peak current handling with 126 V clamping - prevents driver UVLO or shoot-through failure during 24 V system transients. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ78A-E3/5A (Vishay) | Unidirectional; SMA package; lower PPPM (400 W); VBR = 86.7–95.8 V; no AEC-Q101 qualification. | Limited to non-automotive, low-energy 12 V circuits; unsuitable for load dump or under-hood use. | Select only for cost-sensitive industrial sensors where AEC-Q101 and 6600 W surge are unnecessary. |
| TPSMD78CA (Littelfuse) | Bidirectional; same DO-218AC package; PPPM = 6600 W; VBR = 86.7–95.8 V; AEC-Q101 qualified; VC = 126 V at 52.4 A. | Functionally identical performance and qualification; differs only in marking and minor thermal impedance (RθJM = 0.37 °C/W). | Drop-in alternative with identical layout, thermal, and electrical behavior - validated for same automotive OEM specifications. |
Compared with SMAJ78A-E3/5A, SM8S78CAHM3/I delivers 16.5× higher surge power and automotive qualification; versus TPSMD78CA, it offers marginally better thermal conduction (0.35 vs. 0.37 °C/W) and identical clamping, making it preferred for thermally constrained EPS or ADAS modules.
Availability
SM8S78CAHM3/I is available at Aetrix Electronics and suitable for automotive power electronics, engine control units, and ADAS camera modules requiring stable component supply with full AEC-Q101 traceability and DO-218AC thermal performance.
Supply support for SM8S78CAHM3/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 TVS devices for automotive, industrial, and computing markets.
The SM8SxxCA family was engineered specifically for automotive load dump and ISO 16750-2 transient suppression, combining high-power DO-218AC packaging with AEC-Q101 validation and 175 °C junction capability.
FAQ
What is the maximum clamping voltage of the SM8S78CAHM3/I under a 10/1000 μs surge?
The SM8S78CAHM3/I clamps to a maximum of 126 V when subjected to its rated 52.4 A peak pulse current (IPPM) under a 10/1000 μs waveform. This value is measured per Figure 4 in the Vishay datasheet (Doc. #98229) and ensures downstream 24 V-rated ICs remain within safe operating voltage limits during ISO 7637-2 Pulse 5a events. The SM8S78CAHM3/I maintains this clamping performance across its full operating temperature range.
Is the SM8S78CAHM3/I suitable for 24 V automotive systems with load dump requirements?
Yes, the SM8S78CAHM3/I is explicitly designed for 24 V automotive load dump protection. Its 78 V stand-off voltage (VWM), 86.7–95.8 V breakdown range, and 6600 W peak pulse power rating meet ISO 7637-2 Pulse 5a requirements for commercial and heavy-duty vehicles. The SM8S78CAHM3/I is AEC-Q101 qualified and rated for TJ = 175 °C, confirming suitability for under-hood deployment in 24 V architectures.
Does the SM8S78CAHM3/I require orientation during PCB placement?
No, the SM8S78CAHM3/I is a bidirectional TVS diode with no cathode band marking and symmetrical electrical characteristics. Its DO-218AC package has identical anode/cathode behavior in both directions, eliminating orientation dependency during automated pick-and-place. This simplifies manufacturing and avoids field failures caused by incorrect mounting - a key advantage of the SM8S78CAHM3/I over unidirectional alternatives.
What is the thermal resistance from junction to mount (RθJM) for the SM8S78CAHM3/I?
The SM8S78CAHM3/I has a typical junction-to-mount thermal resistance (RθJM) of 0.35 °C/W, as specified in the Thermal Characteristics table of the Vishay datasheet. This ultra-low value is achieved via direct metal heatsink bonding in the DO-218AC package and enables efficient heat transfer to the PCB copper pour or chassis. For reliable operation, Lead 2 (metal heatsink) must be soldered to a ≥100 mm² copper area - a critical design requirement for the SM8S78CAHM3/I.
How does the SM8S78CAHM3/I compare to standard SMAJ series TVS diodes in surge capability?
The SM8S78CAHM3/I delivers 6600 W peak pulse power (10/1000 μs), which is 16.5× higher than the 400 W rating of the SMAJ78A-E3/5A. It also features AEC-Q101 qualification, 175 °C junction rating, and DO-218AC packaging with integrated heatsink - capabilities absent in SMAJ devices. While both share similar VBR and VC, the SM8S78CAHM3/I is engineered for sustained high-energy transients in automotive systems where the SMAJ78A-E3/5A would fail catastrophically.
SM8S78CAHM3/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):
- 78V
- Voltage - Breakdown (Min):
- 86.7V
- Voltage - Clamping (Max) @ Ipp:
- 126V
- Current - Peak Pulse (10/1000µs):
- 52.4A
- 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
SM8S78CAHM3/I FAQ
1.How can I place an order for SM8S78CAHM3/I through Aetrix?
Please submit a Request for Quotation (RFQ) for SM8S78CAHM3/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 SM8S78CAHM3/I reliable?
The price and inventory of SM8S78CAHM3/I are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SM8S78CAHM3/I is usually 5 days.
3.What payment methods are accepted for SM8S78CAHM3/I?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SM8S78CAHM3/I transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SM8S78CAHM3/I?
SM8S78CAHM3/I orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SM8S78CAHM3/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 SM8S78CAHM3/I?
For technical support, including SM8S78CAHM3/I datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SM8S78CAHM3/I requirements.
6.How does Aetrix verify that SM8S78CAHM3/I is sourced from the original manufacturer or authorized distributors?
All SM8S78CAHM3/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 SM8S78CAHM3/I meets industry standards.
7.What is the process for return or replacement of SM8S78CAHM3/I?
All SM8S78CAHM3/I units undergo pre-shipment inspection (PSI). If there is an issue with SM8S78CAHM3/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 SM8S78CAHM3/I part is unused and in its original packaging.
Return procedure for SM8S78CAHM3/I:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SM8S78CAHM3/I Tags
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