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Taiwan Semiconductor Corporation SMAJ70H
- Part No.:
- SMAJ70H
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ70H.pdf
- Description:
- TVS DIODE 70VWM 125VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:7,500
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Product details
Overview
SMAJ70H 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 70 V working stand-off voltage (VWM), 77.8–95.1 V breakdown voltage (VBR), 125 V maximum clamping voltage (VC) at 3.2 A peak impulse current, and 400 W peak pulse power rating (10/1000 µs waveform). It is widely deployed in automotive-grade DC/DC converters to suppress load-dump and ISO 7637-2 Pulse 1/2a/2b/3a/3b transients.
For engineers reviewing the SMAJ70H datasheet, SMAJ70H pinout, SMAJ70H application, or SMAJ70H equivalent, key selection criteria include clamping performance under 10/1000 µs surge, AEC-Q101 qualification status, unidirectional polarity marking, DO-214AC mechanical compatibility, and leakage current ≤1 µA at 70 V - all critical for reliable front-end protection in harsh automotive and industrial environments.
Technical Context
The SMAJ70H operates as a unidirectional avalanche diode, leveraging glass-passivated junction technology for stable breakdown behavior and low leakage. Its clamping response is sub-nanosecond (<1.0 ps from 0 V to VBR min), enabling effective suppression of fast-rising ESD and switching transients.
It meets ISO 7637-2 compliance for automotive electrical disturbances and is rated for continuous operation from −55 °C to +150 °C junction temperature. The device is not bidirectional - polarity is marked on the cathode band per DO-214AC outline, and reverse conduction only occurs above VBR during transient events.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 70 V - Maximum continuous DC or RMS voltage the device blocks without significant leakage |
| VBR @ IT=1 mA | 77.8–95.1 V - Guaranteed avalanche onset range; ensures predictable turn-on during overvoltage events |
| VC @ IPPM=3.2 A | 125 V - Maximum voltage seen across protected circuit during 10/1000 µs surge; defines worst-case stress on downstream components |
| IR @ VWM | ≤1 µA - Ultra-low reverse leakage preserves efficiency in high-impedance bias networks and battery-powered systems |
| PPPM | 400 W - Peak pulse power handling capability with standard 10/1000 µs waveform; derates linearly above 25 °C ambient |
| Junction Temp Range | −55 °C to +150 °C - Enables deployment in under-hood automotive, industrial motor drives, and outdoor power electronics |
| Package | DO-214AC (SMA) - Industry-standard surface-mount outline with matte tin-plated leads, J-STD-002 solderable, MSL Level 1 |
Pinout & Package
DO-214AC (SMA) package: molded plastic case with axial leadform, cathode indicated by a band on the body. Leads are matte tin-plated, compliant with J-STD-002 solderability and JESD201 Class 2 whisker resistance. Weight ≈0.060 g.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Low-side connection point | Connected to ground or low-potential rail; completes conduction path during reverse-biased transient clamp |
| Cathode | High-side connection point | Connected to protected line (e.g., 70 V rail); polarity band must align with PCB silkscreen to prevent misorientation |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive applications including engine control, body electronics, and ADAS power domains |
| Glass passivated junction | Ensures long-term stability of VBR and low parameter drift under thermal cycling and humidity stress |
| Clamping time <1.0 ps | Responds faster than most microcontroller I/O or power MOSFET gate drivers, minimizing transient-induced latch-up risk |
| ISO 7637-2 compliance | Guarantees survivability against standardized automotive transients (Pulse 1, 2a, 2b, 3a, 3b) without degradation |
| Halogen-free & RoHS | Meets IEC 61249-2-21 and EU RoHS Directive 2011/65/EU for environmentally compliant manufacturing |
Applications
| Automotive DC/DC Converter | Industrial SMPS Input Stage |
|---|---|
Use Scenario: Protecting 70 V nominal input rail of a buck converter in an automotive ADAS camera module subjected to load-dump pulses. IC Role / Device Role / Timing Role: Unidirectional TVS placed between VIN and GND, clamping transients before they reach controller IC and power MOSFETs. Use Value: Limits voltage excursion to ≤125 V during 10/1000 µs surges, preventing damage to 100 V-rated input capacitors and gate drivers. | Use Scenario: Safeguarding the primary-side rectifier output in a 70 V industrial switch-mode power supply exposed to lightning-induced surges on AC mains. IC Role / Device Role / Timing Role: Front-end transient suppressor on bulk capacitor node, absorbing energy from fast-rising line transients. Use Value: Withstands 400 W peak pulse power and maintains <1 µA leakage at 70 V, preserving no-load efficiency while ensuring reliability. |
| LED Driver Power Rail | On-Board Charger Interface |
Use Scenario: Protecting constant-current LED driver IC inputs in outdoor street lighting operating from 70 V DC distribution bus. IC Role / Device Role / Timing Role: Standoff protector on driver enable/control lines and power input, suppressing ESD and inductive kickback. Use Value: Sub-nanosecond response prevents logic upset in digital control interfaces; low leakage avoids false triggering in high-impedance sense circuits. | Use Scenario: Shielding communication and power pins of an OBC (on-board charger) interface module connected to 70 V auxiliary battery system. IC Role / Device Role / Timing Role: Bidirectional protection is not required; SMAJ70H provides cost-optimized unidirectional clamping on positive supply rail only. Use Value: AEC-Q101 qualification and −55 °C to +150 °C operation ensure functional safety compliance in EV thermal management zones. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ70AH | Narrower VBR range (77.8–86.0 V vs. 77.8–95.1 V); tighter tolerance improves clamping consistency but reduces margin for VBR drift | Preferred where precise clamping threshold is prioritized over worst-case surge margin | Select SMAJ70AH when design requires tighter VBR matching and lower VC (113 V) under same IPPM |
| SMBJ70A | DO-214AA (SMB) package; 600 W PPPM; higher IPPM (4.3 A); larger footprint and thermal mass | Better suited for higher-energy transients where PCB space allows larger package | Choose SMBJ70A only if 600 W rating is required and DO-214AC footprint cannot accommodate thermal derating needs |
Compared with SMAJ70AH and SMBJ70A, the SMAJ70H offers the broadest VBR window and lowest-cost DO-214AC solution for general-purpose 70 V rail protection - balancing surge margin, footprint, and AEC-Q101 compliance without over-engineering.
Availability
SMAJ70H is available at Aetrix Electronics and suitable for automotive DC/DC converters, industrial SMPS input stages, and LED driver power rails requiring stable component supply, full traceability, and lifecycle continuity support.
Supply support for SMAJ70H 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, MOSFETs, and power management devices.
The SMAJ series was developed specifically for AEC-Q101-compliant, surface-mount transient suppression in automotive and industrial power systems - emphasizing reliability, tight parametric control, and compatibility with automated SMT assembly.
FAQ
What is the maximum clamping voltage of the SMAJ70H under standard test conditions?
The SMAJ70H has a maximum clamping voltage (VC) of 125 V when subjected to a 10/1000 µs waveform with a peak impulse current (IPPM) of 3.2 A. This value is measured per JEDEC standards and represents the worst-case voltage imposed on the protected circuit during surge events. The SMAJ70H maintains this clamping performance across its full operating temperature range of −55 °C to +150 °C.
Is the SMAJ70H suitable for bidirectional transient protection?
No, the SMAJ70H is a unidirectional TVS diode and is not rated for bidirectional operation. It conducts only when the cathode is biased positively relative to the anode beyond its breakdown voltage. For bidirectional protection, TSC offers the SMAJ70CH variant (with CH suffix), which features symmetrical clamping in both polarities. Using SMAJ70H in reverse-biased configurations may result in permanent failure.
Does the SMAJ70H meet automotive qualification standards?
Yes, the SMAJ70H is AEC-Q101 qualified and meets ISO 7637-2 requirements for automotive electrical disturbances, including Pulse 1 (inductive load dump), Pulse 2a/2b (switching transients), and Pulse 3a/3b (capacitive coupling). Its DO-214AC package is rated MSL Level 1 and complies with JESD201 Class 2 whisker testing - confirming suitability for automotive under-hood and chassis applications.
What is the reverse leakage current specification for the SMAJ70H at its working voltage?
The SMAJ70H exhibits a maximum reverse leakage current (IR) of 1 µA when biased at its rated working stand-off voltage (VWM) of 70 V, measured at 25 °C. This ultra-low leakage ensures minimal power loss in standby or battery-backed systems and avoids interference with high-impedance monitoring circuits. Leakage remains within specification up to +150 °C junction temperature.
How does the SMAJ70H compare to the SMAJ70AH in terms of breakdown voltage tolerance?
The SMAJ70H has a wider breakdown voltage (VBR) range of 77.8–95.1 V at 1 mA test current, whereas the SMAJ70AH specifies 77.8–86.0 V - indicating tighter VBR tolerance. This makes SMAJ70AH preferable where consistent clamping onset is critical, while SMAJ70H provides greater margin against VBR drift due to aging or temperature variation. Both share identical package, power rating, and AEC-Q101 qualification.
SMAJ70H 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:
- -
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 150°C (TJ)
- Grade:
- Automotive
- Qualification:
- AEC-Q101
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-214AC (SMA)
SMAJ70H FAQ
1.How can I place an order for SMAJ70H through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ70H 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 SMAJ70H reliable?
The price and inventory of SMAJ70H are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ70H is usually 5 days.
3.What payment methods are accepted for SMAJ70H?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ70H transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ70H?
SMAJ70H orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ70H 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 SMAJ70H?
For technical support, including SMAJ70H datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ70H requirements.
6.How does Aetrix verify that SMAJ70H is sourced from the original manufacturer or authorized distributors?
All SMAJ70H 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 SMAJ70H meets industry standards.
7.What is the process for return or replacement of SMAJ70H?
All SMAJ70H units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ70H, 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 SMAJ70H part is unused and in its original packaging.
Return procedure for SMAJ70H:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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