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Taiwan Semiconductor Corporation SMAJ70A
- Part No.:
- SMAJ70A
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ70A.pdf
- Description:
- TVS DIODE 70VWM 113VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:4,642
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Product details
Overview
SMAJ70A from Taiwan Semiconductor is a unidirectional surface-mount transient voltage suppressor (TVS) diode designed for robust overvoltage protection in DC power rails and signal lines. It features a 70 V working stand-off voltage (VWM), 77.8–86.0 V breakdown voltage (VBR), 113 V maximum clamping voltage (VC) at 3.5 A peak impulse current, and 400 W peak pulse power rating (10/1000 µs waveform). It is widely deployed in industrial DC/DC converters to safeguard sensitive control ICs against ESD and load dump transients.
For engineers reviewing the SMAJ70A datasheet, SMAJ70A pinout, SMAJ70A application, or SMAJ70A equivalent, key selection criteria include its DO-214AC (SMA) package compatibility with automated SMT lines, sub-1 ps response time, <1 µA leakage at 70 V, ISO 7637-2 Pulse 1/2a/2b/3a/3b compliance, and thermal stability up to +150 °C junction temperature.
Technical Context
The SMAJ70A operates as a unidirectional avalanche diode, leveraging glass-passivated junction technology to achieve fast transient suppression with minimal capacitance. Its clamping behavior is defined by a tightly controlled VBR range (77.8–86.0 V @ 1 mA) and low dynamic impedance, ensuring predictable voltage limiting during 10/1000 µs surges.
It is rated for 400 W peak pulse power at TA = 25 °C, derated linearly above that ambient per Fig.2, and supports steady-state power dissipation of 1 W. The device meets JESD201 Class 2 whisker resistance and J-STD-020 Moisture Sensitivity Level 1, enabling reflow-compatible assembly without preconditioning.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 70 V - Maximum continuous reverse operating voltage before significant leakage begins; defines safe DC rail margin. |
| VBR min/max | 77.8 V / 86.0 V @ 1 mA - Breakdown threshold range ensures reliable turn-on across process variation and temperature. |
| VC @ IPPM | 113 V @ 3.5 A - Clamped voltage during 10/1000 µs surge; determines protected circuit's maximum transient stress. |
| PPK | 400 W - Peak pulse power handling capability; enables survival of automotive load dump and ISO 7637-2 pulses. |
| IR @ VWM | <1 µA - Ultra-low reverse leakage preserves efficiency in high-impedance bias networks and battery-powered systems. |
| TJ max | +150 °C - Maximum junction temperature; supports operation in enclosed industrial enclosures and under sustained surge duty. |
| Package | DO-214AC (SMA) - Standardized surface-mount outline with cathode band marking; compatible with IPC-7351B footprint. |
Pinout & Package
DO-214AC (SMA) package: molded epoxy case with matte tin-plated leads, polarity indicated by cathode band. Weight ≈ 0.060 g. Meets UL 94V-0 flammability and JESD201 Class 2 whisker resistance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode (non-banded end) | Input/Line side terminal | Connected to protected line (e.g., +12 V rail); conducts during forward surge or bidirectional clamp if used with external series components. |
| Cathode (banded end) | Clamp reference terminal | Connected to ground or low-impedance return path; defines clamping reference and carries full surge current to GND. |
Key Features
| Feature | Design Value |
|---|---|
| Glass-passivated junction | Ensures stable VBR and low leakage over lifetime and temperature cycling; eliminates passivation-related drift in harsh environments. |
| Sub-1 ps response time | Enables suppression of nanosecond-scale ESD events (IEC 61000-4-2) before downstream ICs experience latch-up or gate oxide damage. |
| ISO 7637-2 compliance | Validated for automotive-grade transients including Pulse 1 (inductive switch-off), Pulse 2a/2b (battery disconnect), and Pulse 3a/3b (ignition noise). |
| Moisture Sensitivity Level 1 | Permits direct placement and reflow without baking; reduces manufacturing overhead and avoids moisture-induced popcorning. |
| Halogen-free & RoHS compliant | Meets IEC 61249-2-21 and EU RoHS Directive 2011/65/EU; supports environmentally regulated industrial and automotive supply chains. |
Applications
| Industrial DC/DC Converters | Automotive Body Control Modules |
|---|---|
Use Scenario: Protecting 5 V or 12 V output rails of isolated flyback or buck-boost converters against input-side transients and cross-talk. IC Role / Device Role: Unidirectional TVS placed between output rail and ground, clamping positive-going surges induced by switching noise or coupled EMI. Use Value: Limits transient overshoot to ≤113 V, preventing damage to downstream LDOs, microcontrollers, and CAN transceivers powered from the same rail. |
Use Scenario: Safeguarding LIN bus interface circuits and LED driver inputs in door modules exposed to battery disconnection and load dump events. IC Role / Device Role: Line-side TVS on 12 V supply input, absorbing ISO 7637-2 Pulse 2a (100 V/50 ms) and Pulse 5a (75 V/400 ms) energy. Use Value: Withstands 400 W peak power without degradation, maintaining clamping performance after repeated automotive transients per AEC-Q101 stress profiles. |
| LED Driver Power Inputs | Industrial SMPS Secondary Side |
Use Scenario: Guarding constant-current LED drivers against voltage spikes caused by inductive kickback from mechanical relays or solenoid loads. IC Role / Device Role: Unidirectional TVS connected across driver input terminals, shunting surge current away from MOSFET gate drivers and current-sense amplifiers. Use Value: 70 V VWM allows use with 48 V nominal LED strings while providing 43 V headroom to VC, avoiding false triggering during normal operation. |
Use Scenario: Protecting secondary-side synchronous rectifiers and optocoupler feedback paths in telecom-grade AC/DC adapters. IC Role / Device Role: Ground-referenced TVS on +5 V or +3.3 V output, suppressing common-mode noise and transformer-coupled surges. Use Value: Low 1 µA leakage at 70 V prevents loading of precision feedback dividers; DO-214AC footprint enables dense layout without compromising creepage. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ70 | Bidirectional variant; symmetric VBR (77.8–95.1 V), higher VC (125 V @ 3.2 A), no polarity marking. | Required where AC-coupled signals or dual-polarity transients (e.g., RS-485, CAN bus) must be suppressed without external rectification. | Select SMAJ70 only when bidirectional clamping is mandatory; SMAJ70A offers lower clamping and tighter VBR tolerance for DC-only rails. |
| SMBJ70A | Same electrical specs but in DO-214AA (SMB) package; 2.5 mm × 4.5 mm vs. SMA's 2.5 mm × 4.0 mm; 600 W PPK. | Preferred where higher surge margin is needed and PCB space allows larger footprint; not drop-in due to different pad layout and thermal mass. | Choose SMBJ70A for enhanced reliability in high-energy environments; SMAJ70A remains optimal for space-constrained SMT designs with standard DO-214AC tooling. |
Compared with SMAJ70 and SMBJ70A, the SMAJ70A delivers the tightest VBR tolerance (±5.2%), lowest clamping voltage (113 V), and smallest footprint-making it ideal for compact, cost-sensitive DC rail protection where unidirectional surges dominate.
Availability
SMAJ70A is available at Aetrix Electronics and suitable for industrial DC/DC converters, automotive body electronics, and LED driver power inputs requiring stable component supply, long-term lifecycle support, and RoHS-compliant sourcing.
Supply support for SMAJ70A 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 semiconductor manufacturer specializing in discrete power devices, TVS diodes, and rectifiers, with global distribution and AEC-Q101-qualified product lines.
The SMAJ series was developed specifically for high-reliability transient suppression in automotive and industrial power systems, emphasizing fast response, low leakage, and robust surge endurance in standardized surface-mount packages.
FAQ
What is the polarity configuration of the SMAJ70A?
The SMAJ70A is a unidirectional TVS diode with clearly marked cathode band. It conducts only in reverse bias during overvoltage events, making it suitable for protecting positive DC rails referenced to ground. Unlike bidirectional variants such as SMAJ70, the SMAJ70A does not suppress negative-going transients unless paired with additional circuitry. Its polarity marking aligns with standard DO-214AC orientation conventions used in automated placement equipment.
Does the SMAJ70A meet automotive transient standards?
Yes, the SMAJ70A meets ISO 7637-2 requirements for Pulse 1 (inductive switch-off), Pulse 2a (battery disconnect), Pulse 2b (alternator field decay), and Pulses 3a/3b (capacitive coupling and ignition noise). Its 400 W peak pulse power rating and 113 V clamping voltage at 3.5 A ensure compliance with these waveforms when applied within its derating envelope. Taiwan Semiconductor validates this performance per the standard test setup, and the SMAJ70A is commonly used in AEC-Q101-compliant modules.
What is the maximum clamping voltage of the SMAJ70A under surge conditions?
The SMAJ70A has a maximum clamping voltage (VC) of 113 V at a peak impulse current (IPPM) of 3.5 A, tested with a 10/1000 µs waveform. This value represents the upper limit of voltage seen by protected circuitry during worst-case surge events. Designers use this parameter to verify that downstream components-such as microcontrollers, gate drivers, or communication ICs-remain within their absolute maximum ratings during transient exposure.
Can the SMAJ70A be used in place of the SMAJ70 in a design?
No-the SMAJ70A and SMAJ70 are not interchangeable without circuit review. The SMAJ70 is bidirectional with symmetric breakdown and higher clamping (125 V), while the SMAJ70A is unidirectional with tighter VBR tolerance and lower clamping (113 V). Substituting SMAJ70A for SMAJ70 on an AC or bidirectional line risks failure during negative transients. Always confirm polarity requirements and validate clamping margins before replacement.
What is the leakage current specification for the SMAJ70A at its working voltage?
The SMAJ70A exhibits a maximum reverse leakage current (IR) of 1 µA at its rated working stand-off voltage (VWM) of 70 V, measured at 25 °C. This ultra-low leakage minimizes standby power loss and avoids interference with high-impedance sensing nodes or battery-backed circuits. Leakage remains well below 5 µA even at elevated temperatures up to +125 °C, supporting reliable operation in thermally demanding environments.
SMAJ70A 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:
- 113V
- Current - Peak Pulse (10/1000µs):
- 3.5A
- 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)
SMAJ70A FAQ
1.How can I place an order for SMAJ70A through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ70A 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 SMAJ70A reliable?
The price and inventory of SMAJ70A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ70A is usually 5 days.
3.What payment methods are accepted for SMAJ70A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ70A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ70A?
SMAJ70A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ70A 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 SMAJ70A?
For technical support, including SMAJ70A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ70A requirements.
6.How does Aetrix verify that SMAJ70A is sourced from the original manufacturer or authorized distributors?
All SMAJ70A 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 SMAJ70A meets industry standards.
7.What is the process for return or replacement of SMAJ70A?
All SMAJ70A units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ70A, 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 SMAJ70A part is unused and in its original packaging.
Return procedure for SMAJ70A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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