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Taiwan Semiconductor Corporation SMAJ8.5
- Part No.:
- SMAJ8.5
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ8.5.pdf
- Description:
- 400W, 10.5V, 10%, UNIDIRECTIONAL
- Quantity:
- Payment:
- Shipping:
Inventory:8,678
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Product details
Overview
SMAJ8.5 from Taiwan Semiconductor is a unidirectional surface-mount transient voltage suppressor (TVS) diode in DO-214AC (SMA) package, designed for clamping fast transients in DC power lines and signal paths. It features a 8.5 V working stand-off voltage (VWM), 9.44–11.50 V breakdown voltage (VBR), 15.9 V maximum clamping voltage (VC) at 25.2 A peak pulse current, and 400 W peak pulse power rating with 10/1000 µs waveform - used in automotive power supply protection and industrial DC/DC converters.
For engineers reviewing the SMAJ8.5 datasheet, SMAJ8.5 pinout, SMAJ8.5 application, or SMAJ8.5 equivalent, key selection criteria include clamping voltage margin vs. protected IC's absolute maximum rating, leakage current at operating voltage (<10 µA @ 8.5 V), unidirectional polarity marking, DO-214AC thermal derating above 25°C, and compliance with ISO 7637-2 Pulse 1/2a/2b/3a/3b for automotive electronics.
Technical Context
The SMAJ8.5 operates as a unidirectional avalanche diode, conducting only when reverse voltage exceeds its specified VBR range (9.44–11.50 V @ 1 mA). Its glass-passivated junction ensures stable breakdown characteristics and low leakage (<10 µA @ VWM = 8.5 V), while sub-1 ps response time enables effective suppression of ESD and load-dump transients.
It is rated for 400 W peak pulse power (10/1000 µs), derated linearly above 25°C ambient per Fig.2, with maximum junction temperature of +150°C and storage range from –55°C to +150°C. The device meets JESD201 Class 2 whisker resistance and UL 94V-0 flammability requirements for PCB-mounted surge protection.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 8.5 V - maximum continuous reverse operating voltage before clamping begins |
| VBR @ IT=1 mA | 9.44–11.50 V - guaranteed avalanche breakdown range defining turn-on threshold |
| VC @ IPPM=25.2 A | 15.9 V - maximum clamped voltage during 10/1000 µs transient, limiting stress on downstream ICs |
| IR @ VWM | <10 µA - ultra-low leakage preserves efficiency in low-power standby circuits |
| PPPM | 400 W - peak pulse power handling capability under standardized 10/1000 µs surge waveform |
| TJ max | +150°C - maximum junction temperature enabling operation in under-hood automotive environments |
| Package | DO-214AC (SMA) - industry-standard surface-mount outline with cathode band marking |
Pinout & Package
DO-214AC (SMA) package: molded plastic case with matte tin-plated leads, polarity indicated by cathode band; weight ≈ 0.060 g; moisture sensitivity level (MSL) 1 per J-STD-020.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction terminal | Connected to lower-potential side (e.g., GND or return path) in unidirectional configuration |
| Cathode (banded end) | Reverse-biased clamping terminal | Connected to protected line (e.g., +12 V rail); conducts during overvoltage to shunt energy to ground |
Key Features
| Feature | Design Value |
|---|---|
| Glass-passivated junction | Ensures stable VBR tolerance and long-term reliability under repeated surge stress |
| Sub-1 ps response time | Enables suppression of nanosecond-scale ESD events before sensitive ICs are damaged |
| ISO 7637-2 compliance | Validated for automotive load-dump (Pulse 5a/b) and coupled transient immunity (Pulses 1, 2a, 2b, 3a, 3b) |
| RoHS & halogen-free | Meets IEC 61249-2-21 and EU RoHS Directive for environmentally compliant manufacturing |
| Automated placement compatible | DO-214AC footprint supports high-speed pick-and-place assembly without lead deformation |
Applications
| Automotive Power Rail Protection | Industrial DC/DC Converter Input |
|---|---|
Use Scenario: Protecting 12 V battery-fed ECUs against load dump (up to +120 V) and alternator switching transients. IC Role / Device Role / Timing Role: Unidirectional TVS placed between battery rail and input filter capacitor to clamp surges before they reach regulator ICs. Use Value: Clamps to ≤15.9 V at 25.2 A, preserving integrity of 16 V-rated input stages in buck controllers and PMICs. | Use Scenario: Safeguarding isolated DC/DC converter primary-side inputs in factory automation PLCs. IC Role / Device Role / Timing Role: Standoff-rated TVS absorbing repetitive 400 W surges induced by relay coil de-energization or inductive load switching. Use Value: 400 W peak power rating and 150°C TJ max support continuous operation in enclosed, high-ambient industrial enclosures. |
| LED Driver Supply Line | USB-C Power Delivery Interface |
Use Scenario: Shielding constant-current LED drivers from voltage spikes caused by hot-plug events or cable inductance. IC Role / Device Role / Timing Role: Unidirectional clamping device placed across input terminals to limit transient overshoot during startup or fault conditions. Use Value: Low 8.5 V VWM allows use with 9–12 V nominal supplies while maintaining sufficient margin above operating voltage. | Use Scenario: Secondary-side transient suppression on USB-C VBUS lines in portable docking stations. IC Role / Device Role / Timing Role: Fast-response TVS absorbing ESD and short-duration surges before they propagate into PD controller or buck converter. Use Value: Sub-1 ps response and <10 µA leakage at 8.5 V minimize impact on VBUS regulation accuracy and standby power budget. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ8.5A | Narrower VBR range (9.44–10.40 V), lower VC (14.4 V @ 27.8 A), tighter tolerance | Better suited for designs requiring tighter clamping voltage control and lower let-through voltage | Select SMAJ8.5A when clamping precision and reduced overshoot are prioritized over cost or availability |
| SMBJ8.5 | Same VWM/VBR specs but in larger DO-214AA (SMB) package; higher PPPM = 600 W | Preferred where higher surge energy absorption or improved thermal dissipation is required | Choose SMBJ8.5 for higher-reliability industrial or automotive applications demanding >400 W margin |
Compared with SMAJ8.5A, the SMAJ8.5 offers wider VBR tolerance and slightly higher clamping voltage, simplifying design margining for less critical rails; versus SMBJ8.5, it trades package size and power rating for board space savings in compact consumer and embedded systems.
Availability
SMAJ8.5 is available at Aetrix Electronics and suitable for automotive electronics, industrial power supplies, LED lighting systems, and USB-C interface protection requiring stable component supply and full traceability.
Supply support for SMAJ8.5 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, serving global automotive, industrial, and consumer markets since 1979.
The SMAJ series is part of TSC's transient voltage suppressor portfolio, engineered specifically for robust, surface-mount surge protection in harsh environments including automotive power networks and industrial power conversion systems.
FAQ
What is the maximum clamping voltage of the SMAJ8.5 under standard test conditions?
The SMAJ8.5 has a maximum clamping voltage (VC) of 15.9 V when subjected to a 10/1000 µs peak pulse current of 25.2 A. This value is measured per JEDEC standards and defines the upper voltage limit imposed on protected circuitry during transient events. Designers must ensure this clamping level remains below the absolute maximum rating of downstream components. The SMAJ8.5 achieves this performance within its DO-214AC package while maintaining low leakage and fast response.
Is the SMAJ8.5 suitable for bidirectional transient suppression?
No, the SMAJ8.5 is a unidirectional TVS diode, intended for suppression on polarized DC lines such as positive power rails referenced to ground. For bidirectional applications (e.g., AC signal lines or data buses), the SMAJ8.5A variant is not applicable - instead, devices with "CA" suffix (e.g., SMAJ8.5CA) or explicitly rated bidirectional types must be selected. The SMAJ8.5's cathode band marking and electrical specifications confirm its unidirectional functionality, and using it in reverse-biased AC configurations may result in failure.
How does the SMAJ8.5 comply with automotive transient immunity standards?
The SMAJ8.5 meets ISO 7637-2 requirements for Pulses 1, 2a, 2b, 3a, and 3b - covering typical conducted transients in 12 V vehicle electrical systems, including switch-off inductive spikes, load dump simulations, and capacitive coupling events. Its 400 W peak pulse rating, fast sub-1 ps response, and stable clamping behavior under temperature variation enable reliable protection in ECUs, body control modules, and infotainment power supplies. The SMAJ8.5 is validated per these waveforms in TSC's characterization reports.
What is the leakage current specification for the SMAJ8.5 at its working voltage?
The SMAJ8.5 exhibits a maximum reverse leakage current (IR) of 10 µA when biased at its rated working stand-off voltage (VWM) of 8.5 V, tested at 25°C. This ultra-low leakage minimizes quiescent power loss in always-on circuits and avoids false triggering in high-impedance sensing nodes. The value is confirmed in TSC's Electrical Specifications table and remains well below thresholds that would affect battery-life-critical applications or precision reference circuits powered through the protected rail.
Can the SMAJ8.5 be used in place of the SMAJ8.0 or SMAJ9.0 in an existing design?
Direct substitution of SMAJ8.5 for SMAJ8.0 or SMAJ9.0 requires verification of system-level voltage margins: SMAJ8.5 has VWM = 8.5 V (vs. 8.0 V and 9.0 V), VBR min = 9.44 V (vs. 8.89 V and 10.0 V), and VC = 15.9 V (vs. 15.0 V and 16.9 V). While all share DO-214AC packaging and pinout, the change affects clamping headroom and leakage profile. The SMAJ8.5 is not a drop-in replacement; redesign validation is recommended to confirm compatibility with protected IC's absolute maximum ratings and surge energy profiles.
SMAJ8.5 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):
- 8.5V
- Voltage - Breakdown (Min):
- 9.44V
- Voltage - Clamping (Max) @ Ipp:
- 15.9V
- Current - Peak Pulse (10/1000µs):
- 25.2A
- 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)
SMAJ8.5 FAQ
1.How can I place an order for SMAJ8.5 through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ8.5 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 SMAJ8.5 reliable?
The price and inventory of SMAJ8.5 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ8.5 is usually 5 days.
3.What payment methods are accepted for SMAJ8.5?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ8.5 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ8.5?
SMAJ8.5 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ8.5 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 SMAJ8.5?
For technical support, including SMAJ8.5 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ8.5 requirements.
6.How does Aetrix verify that SMAJ8.5 is sourced from the original manufacturer or authorized distributors?
All SMAJ8.5 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 SMAJ8.5 meets industry standards.
7.What is the process for return or replacement of SMAJ8.5?
All SMAJ8.5 units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ8.5, 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 SMAJ8.5 part is unused and in its original packaging.
Return procedure for SMAJ8.5:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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