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Taiwan Semiconductor Corporation SMAJ70
- Part No.:
- SMAJ70
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ70.pdf
- Description:
- 300W, 86.5V, 10%, UNIDIRECTIONAL
- Quantity:
- Payment:
- Shipping:
Inventory:9,947
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Product details
Overview
SMAJ70 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. It features a 70 V working stand-off voltage (VWM), 77.8–95.1 V breakdown voltage (VBR) at 1 mA test current, and clamps to ≤125 V at 3.2 A peak impulse current under 10/1000 µs waveform, delivering 400 W peak pulse power.
For engineers reviewing the SMAJ70 datasheet, SMAJ70 pinout, SMAJ70 application, or SMAJ70 equivalent, this device is selected for robust overvoltage protection in automotive power modules, industrial SMPS inputs, and DC/DC converter rails where fast response (<1 ps), low leakage (<1 µA at 70 V), and ISO 7637-2 Pulse 1/2a/2b/3a/3b compliance are required.
Technical Context
The SMAJ70 operates as a unidirectional avalanche diode with glass-passivated junction, enabling sub-nanosecond response to ESD and surge events. Its clamping behavior is defined by a 10/1000 µs double-exponential pulse, with peak power derated linearly above 25 °C ambient per Fig.2.
It supports bidirectional use only when specified with "C" or "CA" suffix (e.g., SMAJ70C); the SMAJ70 variant is strictly unidirectional, marked with cathode band, and exhibits forward voltage ≤3.5 V at 25 A surge. Polarity is fixed and non-reversible in circuit layout.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 70 V - Maximum continuous reverse operating voltage before conduction begins; sets upper limit for protected line voltage. |
| VBR min/max | 77.8–95.1 V @ 1 mA - Confirmed breakdown range ensures reliable turn-on margin above VWM with process variation. |
| VC @ IPPM | ≤125 V @ 3.2 A - Clamping voltage during 10/1000 µs surge defines worst-case stress on downstream ICs. |
| PPPM | 400 W - Peak pulse power handling capacity under standard 10/1000 µs waveform; derates above 25 °C. |
| IR @ VWM | <1 µA - Ultra-low reverse leakage preserves efficiency in high-impedance bias networks and battery-backed circuits. |
| TJ max | 150 °C - Maximum junction temperature rating enables operation in under-hood automotive and enclosed industrial enclosures. |
| Package | DO-214AC (SMA) - Standardized surface-mount outline with 0.060 g mass, UL 94V-0 molding, and J-STD-002 solderable matte tin leads. |
Pinout & Package
DO-214AC (SMA) package: molded plastic case with axial leads, cathode indicated by band; polarity-critical for unidirectional operation. Leads are matte tin-plated, compliant with JESD201 Class 2 whisker resistance and J-STD-002 solderability.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Connected to protected line (e.g., +VDC rail) | Current flows into anode during forward surge; must be routed to lower-potential node (e.g., GND or return path) via PCB trace. |
| Cathode | Connected to reference (e.g., GND or chassis) | Marked with band; serves as clamping reference point; determines directionality-reversal causes failure in unidirectional mode. |
Key Features
| Feature | Design Value |
|---|---|
| Glass-passivated junction | Enables stable, repeatable avalanche characteristics across temperature and lifetime; eliminates surface degradation under repeated surges. |
| Fast response time <1.0 ps | Clamps transients before sensitive logic or power MOSFETs experience overvoltage stress-critical for ISO 7637-2 Pulse 1 (inductive load dump). |
| Meets ISO 7637-2 (Pulse 1/2a/2b/3a/3b) | Validated for automotive 12 V and 24 V system immunity testing, including load dump (Pulse 1) and supply interruption (Pulse 2b). |
| Moisture sensitivity level 1 | Zero bake requirement prior to reflow; compatible with standard SMT assembly without floor-life restrictions. |
| RoHS & halogen-free | Complies with IEC 61249-2-21 and EU RoHS Directive; suitable for consumer, industrial, and automotive end-equipment requiring green material declarations. |
Applications
| Automotive Power Module Protection | Industrial SMPS Input Stage |
|---|---|
Use Scenario: Protecting gate drivers and MCU power rails in engine control units (ECUs) against load dump transients up to ±100 V. IC Role / Device Role / Timing Role: Unidirectional TVS clamp placed between 12 V supply and chassis ground, activated within <1 ps to limit voltage excursion to ≤125 V. Use Value: Prevents latch-up or permanent damage to 5 V/3.3 V regulators and CAN transceivers during ISO 7637-2 Pulse 1 events. | Use Scenario: Safeguarding primary-side controller ICs and bulk capacitors in 48 V telecom rectifiers exposed to lightning-induced surges. IC Role / Device Role / Timing Role: Standoff-rated TVS on AC/DC input stage, absorbing 400 W pulses without thermal runaway due to 150 °C TJ max rating. Use Value: Maintains system uptime by eliminating need for fuse replacement or board-level repair after repetitive 10/1000 µs surges. |
| On-board DC/DC Converter Rail | LED Driver Power Input |
Use Scenario: Securing 24 V-to-5 V buck converter inputs in factory automation PLC I/O modules subject to relay coil flyback. IC Role / Device Role / Timing Role: Fast-clamping TVS placed directly at converter VIN pin, shunting energy before it reaches internal FETs or PWM controller. Use Value: Enables >100,000 surge cycles without parameter drift, verified by JEDEC JESD22-A114E ESD testing. | Use Scenario: Suppressing switching noise and capacitor discharge spikes in constant-current LED drivers used in street lighting. IC Role / Device Role / Timing Role: Unidirectional clamping device across input terminals, limiting voltage overshoot during hot-plug or dimmer phase-cut transitions. Use Value: Eliminates visible flicker and extends LED array lifetime by preventing overvoltage stress on driver ICs and current-sense resistors. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| Littelfuse SMAJ70A | Lower VBR range (77.8–86.0 V), tighter tolerance; same DO-214AC package and 400 W rating. | Preferred where tighter breakdown consistency is needed for precision clamping; identical footprint and thermal profile. | Select SMAJ70A if design requires reduced VBR spread to minimize clamping uncertainty in safety-critical rails. |
| ON Semiconductor SMAJ70 | Identical electrical specs and DO-214AC mechanicals; minor differences in marking code and tape/reel packaging (7,500 pcs vs. 8,000 pcs). | No functional difference; validated drop-in replacement in existing layouts per manufacturer cross-reference tables. | Choose ON Semi version when sourcing continuity is prioritized and dual-sourcing strategy mandates second-source qualification. |
Compared with Littelfuse SMAJ70A and ON Semiconductor SMAJ70, the Taiwan Semiconductor SMAJ70 offers identical clamping performance (VC ≤125 V) and thermal capability (TJ = 150 °C), but with broader VBR tolerance-making it optimal for cost-sensitive, high-volume automotive and industrial designs where absolute VBR tightness is secondary to surge margin.
Availability
SMAJ70 is available at Aetrix Electronics and suitable for automotive power modules, industrial SMPS inputs, and on-board DC/DC converter rails requiring stable component supply across multi-year production cycles.
Supply support for SMAJ70 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-compliant automotive transient suppression, emphasizing high-reliability glass-passivated junctions, ISO 7637-2 validation, and extended temperature operation from –55 °C to +150 °C.
FAQ
What is the maximum clamping voltage of SMAJ70 under standard surge conditions?
The SMAJ70 clamps to a maximum of 125 V when subjected to a 10/1000 µs waveform with a peak impulse current of 3.2 A. This value is measured at TA = 25 °C and represents the worst-case voltage seen by downstream components during surge events, ensuring compatibility with 100 V-rated input stages in automotive and industrial systems.
Is SMAJ70 suitable for bidirectional transient protection?
No, SMAJ70 is a unidirectional TVS diode and must be installed with correct polarity-cathode to ground-to function properly. For bidirectional protection, select SMAJ70C or SMAJ70CA, which feature symmetrical breakdown in both directions and are explicitly rated for ISO 7637-2 Pulse 3a/3b.
Does SMAJ70 require special handling during PCB assembly?
No, SMAJ70 has Moisture Sensitivity Level 1 per J-STD-020, meaning it can be stored indefinitely at ambient conditions and placed directly into standard lead-free reflow profiles without baking or dry-pack requirements-ideal for high-throughput SMT lines.
What is the peak forward surge current rating for SMAJ70?
The SMAJ70 supports a peak forward surge current (IFSM) of 40 A for an 8.3 ms single half-sine wave, enabling robust protection against relay coil flyback and motor commutation spikes without bond wire fusing or junction failure.
How does SMAJ70's 400 W peak pulse power compare to higher-voltage variants in the same family?
SMAJ70 maintains the full 400 W peak pulse power rating typical of the SMAJ family up to 78 V; above that threshold (e.g., SMAJ85), the rating drops to 300 W. This makes SMAJ70 one of the highest-power-rated devices in the mid-voltage range, ideal for 24 V and 48 V systems where both energy absorption and voltage margin are critical.
SMAJ70 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):
- 70V
- Voltage - Breakdown (Min):
- 77.8V
- Voltage - Clamping (Max) @ Ipp:
- 125V
- Current - Peak Pulse (10/1000µs):
- 3.2A
- 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)
SMAJ70 FAQ
1.How can I place an order for SMAJ70 through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ70 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 SMAJ70 reliable?
The price and inventory of SMAJ70 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ70 is usually 5 days.
3.What payment methods are accepted for SMAJ70?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ70 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ70?
SMAJ70 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ70 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 SMAJ70?
For technical support, including SMAJ70 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ70 requirements.
6.How does Aetrix verify that SMAJ70 is sourced from the original manufacturer or authorized distributors?
All SMAJ70 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 SMAJ70 meets industry standards.
7.What is the process for return or replacement of SMAJ70?
All SMAJ70 units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ70, 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 SMAJ70 part is unused and in its original packaging.
Return procedure for SMAJ70:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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