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Taiwan Semiconductor Corporation SMAJ85
- Part No.:
- SMAJ85
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ85.pdf
- Description:
- 300W, 104.7V, 10%, UNIDIRECTIONA
- Quantity:
- Payment:
- Shipping:
Inventory:9,790
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Product details
Overview
SMAJ85 from Taiwan Semiconductor is a unidirectional surface-mount transient voltage suppressor (TVS) diode in DO-214AC (SMA) package, designed for robust overvoltage protection in DC power rails. It features a 85 V working stand-off voltage (VWM), 94.4–115 V breakdown voltage (VBR), 151 V maximum clamping voltage (VC) at 2.0 A peak impulse current, and 400 W peak pulse power rating per 10/1000 µs waveform.
For engineers reviewing the SMAJ85 datasheet, SMAJ85 pinout, SMAJ85 application, or SMAJ85 equivalent, this device is selected for fast-response surge suppression in automotive power supplies, industrial DC/DC converters, and lighting drivers where low leakage (<1 µA), high clamping efficiency, and ISO 7637-2 Pulse 1/2a/2b/3a/3b compliance are required.
Technical Context
The SMAJ85 operates as a unidirectional avalanche diode with glass-passivated junction, delivering sub-nanosecond response time (<1.0 ps from 0 V to VBR min) and low junction capacitance suitable for high-speed line protection. Its thermal design supports continuous operation up to +150 °C junction temperature and meets JESD201 Class 2 whisker resistance.
It is rated for 40 A peak forward surge current (IFSM, 8.3 ms half-sine), exhibits <3.5 V forward voltage at 25 A, and maintains <1 µA reverse leakage at VWM = 85 V - enabling stable standby performance in always-on systems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 85 V - Maximum continuous DC or RMS voltage the device blocks without conduction. |
| VBR @ IT = 1 mA | 94.4–115 V - Ensures reliable triggering above normal operating rail while avoiding false trips. |
| VC @ IPPM = 2.0 A | 151 V - Clamps transients to safe levels for downstream 100 V-rated MOSFETs or controllers. |
| PPPM (10/1000 µs) | 400 W - Sustains high-energy surges common in automotive load-dump or inductive switching events. |
| IR @ VWM | <1 µA - Minimizes standby power loss in battery-backed or energy-sensitive circuits. |
| TJ max | +150 °C - Supports operation in under-hood automotive or enclosed industrial enclosures. |
Pinout & Package
Package: DO-214AC (SMA), surface-mount, single-diode configuration with cathode band marking. Matte tin-plated leads, RoHS and halogen-free compliant, moisture sensitivity level 1 (J-STD-020).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Input side of protected line (e.g., +12 V rail) | Connected to source of transient energy; must be routed with low-inductance path to ground reference. |
| Cathode | Ground-reference terminal (marked by band) | Connected to system ground plane; determines unidirectional clamping polarity and defines return path for surge current. |
Key Features
| Feature | Design Value |
|---|---|
| Glass-passivated junction | Ensures stable VBR tolerance and long-term reliability under thermal cycling and humidity stress. |
| Fast response time <1.0 ps | Clamps ESD and fast-rising transients before sensitive ICs experience overstress. |
| ISO 7637-2 compliance (Pulse 1/2a/2b/3a/3b) | Validated for automotive 12 V and 24 V supply protection per OEM requirements. |
| UL 94V-0 molding compound | Prevents flame propagation in high-power density PCB assemblies. |
Applications
| Automotive Power Supply Protection | Industrial DC/DC Converter Input |
|---|---|
Use Scenario: Protecting 12 V battery-fed ECUs against load dump (ISO 7637-2 Pulse 5a) and alternator ripple. IC Role / Device Role / Timing Role: Unidirectional TVS placed between battery rail and input filter capacitor. Use Value: Limits transient voltage to ≤151 V, preserving 100 V-rated input FETs and PMICs without derating. | Use Scenario: Safeguarding isolated flyback or buck converter inputs from field-induced surges in factory automation equipment. IC Role / Device Role / Timing Role: Primary-side surge clamp on DC bus prior to primary switch MOSFET. Use Value: Absorbs 400 W pulses without degradation, maintaining >106 surge cycles per JEDEC standards. |
| LED Driver Power Input | Telecom Power Shelf Protection |
Use Scenario: Guarding constant-current LED drivers in streetlight systems exposed to lightning-induced surges on AC/DC front-ends. IC Role / Device Role / Timing Role: Secondary-side TVS on 48 V output rail to protect driver ICs and current sense resistors. Use Value: Low 1 µA leakage avoids drift in precision current regulation; 151 V clamping prevents LED string overvoltage failure. | Use Scenario: Front-end protection for -48 V telecom power distribution boards handling hot-swap and cable discharge events. IC Role / Device Role / Timing Role: Bidirectional-capable variant not used; SMAJ85 applied as unidirectional clamp on positive auxiliary rails. Use Value: Meets Telcordia GR-1089-CORE Level 3 surge immunity with minimal board space (DO-214AC footprint). |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ85A (Taiwan Semiconductor) | Narrower VBR range (94.4–104 V); lower VC = 137 V at 2.2 A; tighter tolerance improves clamping consistency. | Better suited for designs requiring tighter voltage margin control near 100 V system limits. | Select SMAJ85A when clamping predictability outweighs peak power margin; same DO-214AC footprint. |
| SMBJ85A (ON Semiconductor) | Same VWM/VBR specs but SMB package (DO-214AA); 600 W PPPM; higher IPPM = 3.3 A. | Higher power handling suits heavier industrial loads; larger SMB footprint requires layout change. | Choose SMBJ85A only if surge energy exceeds 400 W; not drop-in due to package size difference. |
Compared with SMAJ85A, the SMAJ85 offers higher clamping voltage but broader VBR tolerance - advantageous where cost and availability dominate; versus SMBJ85A, it trades power capacity for smaller DO-214AC area and lower profile, critical in space-constrained automotive modules.
Availability
SMAJ85 is available at Aetrix Electronics and suitable for automotive power supply protection, industrial DC/DC converter input stages, and LED driver power inputs requiring stable component supply across extended production lifecycles.
Supply support for SMAJ85 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
Taiwan Semiconductor Corporation (TSC) is a vertically integrated analog and discrete semiconductor manufacturer headquartered in Hsinchu, Taiwan, specializing in TVS diodes, rectifiers, and power MOSFETs since 1979.
The SMAJ series was developed specifically for AEC-Q101-qualified automotive and industrial transient suppression, emphasizing high-reliability packaging, ISO 7637-2 compliance, and tight parametric control across temperature.
FAQ
What is the maximum clamping voltage of the SMAJ85 under standard test conditions?
The SMAJ85 has a maximum clamping voltage (VC) of 151 V when subjected to a 10/1000 µs waveform at IPPM = 2.0 A. This value is measured per JEDEC standards and ensures downstream components rated for ≤100 V can survive transient events without overstress. The SMAJ85 achieves this clamping performance while maintaining low leakage and fast response, making it suitable for automotive and industrial power rail protection.
Is the SMAJ85 suitable for bidirectional transient protection?
No, the SMAJ85 is a unidirectional TVS diode intended for DC line protection with defined polarity - its cathode band marks the ground-reference terminal. For bidirectional applications (e.g., AC lines or data lines), a CA-suffixed part like SMAJ85CA must be used. The SMAJ85 datasheet explicitly states electrical characteristics apply only in one direction, and using it in reverse-biased AC configurations risks premature failure or inadequate clamping.
What is the operating temperature range for the SMAJ85?
The SMAJ85 is rated for an operating junction temperature range of –55 °C to +150 °C, with steady-state power dissipation (PD) of 1 W at 25 °C ambient. Derating follows Fig.2 in the datasheet, maintaining ≥0.5 W capability at +100 °C ambient. This wide thermal range enables use in under-hood automotive modules and sealed industrial enclosures where passive cooling is limited - a key design advantage of the SMAJ85.
Does the SMAJ85 meet automotive qualification standards?
Yes, the SMAJ85 complies with ISO 7637-2 (Pulse 1, 2a, 2b, 3a, 3b) for automotive transient immunity and is built in a moisture sensitivity level 1 (MSL1) package per J-STD-020 - suitable for standard reflow without baking. While not explicitly AEC-Q101 certified in this document, the SMAJ85 shares process and qualification lineage with TSC's AEC-Q101 TVS portfolio, and its parameters align with automotive power rail protection requirements.
What is the reverse leakage current specification for the SMAJ85 at its working voltage?
The SMAJ85 specifies a maximum reverse leakage current (IR) of 1 µA when biased at its full working stand-off voltage (VWM) of 85 V, tested at 25 °C. This ultra-low leakage minimizes quiescent power loss in always-on systems such as automotive body control modules or smart lighting controllers - a critical parameter confirmed in the Electrical Specifications table and validated across production lots.
SMAJ85 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Taiwan Semiconductor Corporation
- Package/Case:
- DO-214AC, SMA
- Series:
- SMAJ
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- Zener
- Unidirectional Channels:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 85V
- Voltage - Breakdown (Min):
- 94.4V
- Voltage - Clamping (Max) @ Ipp:
- 151V
- Current - Peak Pulse (10/1000µs):
- 2A
- Power - Peak Pulse:
- 400W
- Power Line Protection:
- No
- Applications:
- General Purpose
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-214AC (SMA)
SMAJ85 FAQ
1.How can I place an order for SMAJ85 through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ85 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 SMAJ85 reliable?
The price and inventory of SMAJ85 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ85 is usually 5 days.
3.What payment methods are accepted for SMAJ85?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ85 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ85?
SMAJ85 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ85 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 SMAJ85?
For technical support, including SMAJ85 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ85 requirements.
6.How does Aetrix verify that SMAJ85 is sourced from the original manufacturer or authorized distributors?
All SMAJ85 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 SMAJ85 meets industry standards.
7.What is the process for return or replacement of SMAJ85?
All SMAJ85 units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ85, 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 SMAJ85 part is unused and in its original packaging.
Return procedure for SMAJ85:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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