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Taiwan Semiconductor Corporation SMAJ70C
- Part No.:
- SMAJ70C
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ70C.pdf
- Description:
- 300W, 86.5V, 10%, BIDIRECTIONAL,
- Quantity:
- Payment:
- Shipping:
Inventory:9,360
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Product details
Overview
SMAJ70C from Taiwan Semiconductor is a unidirectional 400W surface-mount transient voltage suppressor (TVS) diode in DO-214AC (SMA) package, with 70V working stand-off voltage (VWM), 77.8–95.1V breakdown voltage (VBR), and 125V maximum clamping voltage (VC) at 3.2A peak impulse current. It delivers fast response (<1.0ps), low leakage (<1µA), and meets ISO 7637-2 Pulse 1/2a/2b/3a/3b for automotive electronics protection.
For engineers reviewing the SMAJ70C datasheet, SMAJ70C pinout, SMAJ70C application, or SMAJ70C equivalent, this page provides verified electrical parameters, clamping behavior under 10/1000µs surge, junction temperature limits (–55°C to +150°C), RoHS/halogen-free compliance, and direct alternatives for overvoltage protection in DC/DC converters, SMPS, and lighting systems.
Technical Context
The SMAJ70C operates as a unidirectional avalanche diode, conducting only in reverse bias above VBR to clamp transients. Its glass-passivated junction ensures stable breakdown and low leakage, while the DO-214AC package supports automated placement and withstands 40A IFSM surge (8.3ms half-sine).
It is rated for 400W peak pulse power (10/1000µs waveform) up to 78V; above that, derating applies per Fig.2. The device is moisture sensitivity level 1 (J-STD-020) and UL 94V-0 compliant, with matte tin-plated leads solderable per J-STD-002.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 70 V - Maximum continuous reverse operating voltage before conduction begins |
| VBR min/max | 77.8 V / 95.1 V @ 1 mA - Confirmed breakdown range ensuring reliable turn-on margin above VWM |
| VC @ IPPM | 125 V @ 3.2 A - Clamping voltage during 10/1000µs surge, limiting downstream voltage stress |
| PPPM | 400 W (≤78V), derated above - Peak pulse power handling capability defining transient energy absorption |
| IR @ VWM | <1 µA - Ultra-low reverse leakage preserving system efficiency in standby or low-power modes |
| TJ max | +150 °C - Maximum junction temperature enabling operation in high-ambient industrial environments |
| Package | DO-214AC (SMA) - Standardized surface-mount outline with 0.060 g mass and JESD201 Class 2 whisker resistance |
Pinout & Package
DO-214AC (SMA) package: molded plastic case with cathode band marking polarity; matte tin-plated leads; UL 94V-0 flammability rating; weight ≈ 0.060 g.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction terminal | Connected to lower-potential side (e.g., ground or return path) in unidirectional configuration |
| Cathode | Reverse-bias clamping terminal | Connected to protected line (e.g., 70V rail); conducts when transient exceeds VBR |
Key Features
| Feature | Design Value |
|---|---|
| Fast response time | <1.0 ps - Enables suppression of nanosecond-scale ESD and switching transients before IC damage occurs |
| Glass passivated junction | Stable VBR tolerance and low IR drift across temperature and life cycle |
| ISO 7637-2 compliance | Validated for Pulse 1 (inductive load dump), Pulse 2a/2b (switching transients), and Pulse 3a/3b (line impedance coupling) |
| Automated placement compatibility | DO-214AC footprint and lead coplanarity support high-yield SMT assembly without rework |
Applications
| Automotive Power Distribution | Industrial DC/DC Converters |
|---|---|
Use Scenario: Protecting 12V/24V supply lines in body control modules against load dump and inductive kickback per ISO 7637-2 Pulse 1 and 2b. IC Role / Device Role / Timing Role: Unidirectional TVS placed between battery rail and downstream regulator input. Use Value: Limits clamped voltage to ≤125V during 400W surges, preventing MOSFET gate oxide failure and LDO overvoltage shutdown. | Use Scenario: Safeguarding isolated flyback or buck converter outputs against cross-regulation spikes and ESD events on secondary-side sensing lines. IC Role / Device Role / Timing Role: Standoff-clamp protection on regulated output rail (e.g., 70V auxiliary bias supply). Use Value: Maintains <1µA leakage at 70V, avoiding regulation error or quiescent current inflation in precision feedback paths. |
| LED Driver Front-End | Telecom Power Interface |
Use Scenario: Input-stage surge protection for constant-current LED drivers subjected to lightning-induced surges on AC/DC adapter inputs. IC Role / Device Role / Timing Role: Primary-side TVS across bulk capacitor terminals in offline LED driver designs. Use Value: Absorbs 400W 10/1000µs pulses without degradation, preserving driver IC lifetime under repeated surge stress. | Use Scenario: Overvoltage hardening of 48V DC power interface in PoE-powered telecom equipment exposed to field wiring transients. IC Role / Device Role / Timing Role: Secondary-side clamping on powered-device (PD) input before hot-swap controller and DC/DC stage. Use Value: Clamps to 125V within <1ps, ensuring upstream PD controller remains within absolute maximum ratings during surge events. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ70A | Narrower VBR range (77.8–86.0 V) and lower VC (113 V @ 3.5 A); same package and VWM | Better clamping performance for tighter voltage margins; slightly reduced surge current rating | Select SMAJ70A when system-level clamping headroom is constrained below 120 V |
| SMBJ70C | Same VWM/VBR/VC specs but in larger DO-214AA (SMB) package; higher PPPM (600 W) | Requires PCB layout change; suited for higher-energy surge environments where 400W is marginal | Choose SMBJ70C only if thermal derating or surge repetition rate demands >400W capability |
Compared with SMAJ70A, the SMAJ70C offers higher clamping voltage but wider VBR tolerance-beneficial where input variation or temperature drift may push operation near VBR min. Against SMBJ70C, SMAJ70C trades power rating for smaller footprint and cost, making it optimal for space-constrained 70V rail protection.
Availability
SMAJ70C is available at Aetrix Electronics and suitable for automotive power distribution, industrial DC/DC converters, and LED driver front-end designs requiring stable component supply, consistent parametric performance, and full traceability.
Supply support for SMAJ70C 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 industrial, automotive, and consumer markets since 1979.
The SMAJ series was designed specifically for robust, surface-mount transient suppression in harsh environments-emphasizing low leakage, tight VBR consistency, and ISO 7637-2 compliance for automotive-grade reliability.
FAQ
What is the maximum clamping voltage of the SMAJ70C under standard test conditions?
The SMAJ70C has a maximum clamping voltage (VC) of 125 V when subjected to its rated peak impulse current of 3.2 A using the 10/1000 µs waveform. This value is measured per JEDEC standards and defines the upper voltage limit imposed on protected circuitry during surge events. The SMAJ70C maintains this clamping performance across its specified operating temperature range and is validated in the official Taiwan Semiconductor datasheet revision U2102.
Is the SMAJ70C unidirectional or bidirectional, and how is polarity marked?
The SMAJ70C is a unidirectional TVS diode, intended for use in circuits where reverse polarity protection is not required. Polarity is indicated by a cathode band on the DO-214AC (SMA) package body-this band must be oriented toward the higher-potential side of the protected line. Bidirectional variants use the "CA" suffix (e.g., SMAJ70CA); the "C" suffix in SMAJ70C denotes unidirectional construction with standard cathode marking.
Does the SMAJ70C meet automotive transient immunity standards?
Yes, the SMAJ70C meets ISO 7637-2 requirements for Pulse 1 (inductive load dump), Pulse 2a/2b (switching transients), and Pulse 3a/3b (capacitive coupling). These validations are explicitly stated in the Taiwan Semiconductor datasheet (U2102) and confirm suitability for automotive power network protection. The SMAJ70C's 400W peak pulse rating, fast response, and low leakage make it appropriate for 12V and 24V vehicle subsystems including body control modules and lighting ECUs.
What is the junction temperature range and steady-state power dissipation of the SMAJ70C?
The SMAJ70C supports an operating junction temperature range of –55°C to +150°C and a steady-state power dissipation (PD) of 1 W at TA = 25°C. Its thermal design allows reliable operation in high-ambient industrial enclosures or under-hood automotive locations. Derating curves (Fig.2 in the datasheet) define linear reduction of peak pulse power above 25°C ambient, ensuring safe operation up to the maximum TJ limit without thermal runaway.
How does the SMAJ70C compare to the SMAJ70A in terms of breakdown voltage and clamping performance?
The SMAJ70C has a VBR range of 77.8–95.1 V and clamps to 125 V at 3.2 A, whereas the SMAJ70A specifies 77.8–86.0 V VBR and clamps to 113 V at 3.5 A. The SMAJ70A offers tighter VBR tolerance and lower VC, improving voltage margin in precision rails-but with slightly reduced surge current capacity. Both share identical VWM (70 V), package (DO-214AC), and RoHS/halogen-free compliance. The SMAJ70C remains preferred where broader VBR tolerance accommodates manufacturing spread or temperature drift.
SMAJ70C 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:
- -
- Bidirectional Channels:
- 1
- 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)
SMAJ70C FAQ
1.How can I place an order for SMAJ70C through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ70C 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 SMAJ70C reliable?
The price and inventory of SMAJ70C are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ70C is usually 5 days.
3.What payment methods are accepted for SMAJ70C?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ70C transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ70C?
SMAJ70C orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ70C 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 SMAJ70C?
For technical support, including SMAJ70C datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ70C requirements.
6.How does Aetrix verify that SMAJ70C is sourced from the original manufacturer or authorized distributors?
All SMAJ70C 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 SMAJ70C meets industry standards.
7.What is the process for return or replacement of SMAJ70C?
All SMAJ70C units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ70C, 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 SMAJ70C part is unused and in its original packaging.
Return procedure for SMAJ70C:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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