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Taiwan Semiconductor Corporation SMAJ70AH
- Part No.:
- SMAJ70AH
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ70AH.pdf
- Description:
- TVS DIODE 70VWM 113VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:9,562
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Product details
Overview
SMAJ70AH 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), 77.8–86.0 V breakdown voltage (VBR), 113 V maximum clamping voltage (VC) at 3.5 A peak impulse current, and 400 W peak pulse power rating with 10/1000 µs waveform - deployed in automotive-grade SMPS and on-board DC/DC converters.
For engineers reviewing the SMAJ70AH datasheet, SMAJ70AH pinout, SMAJ70AH application, or SMAJ70AH equivalent, key selection criteria include clamping performance under ISO 7637-2 Pulse 1/2a/2b/3a/3b stress, AEC-Q101 qualification status, moisture sensitivity level (MSL 1), and unidirectional polarity marking for correct PCB orientation during automated placement.
Technical Context
The SMAJ70AH operates as a unidirectional avalanche diode, leveraging glass-passivated junction technology to achieve sub-1 ps response time from 0 V to VBR(min). Its clamping behavior is defined by a single-die structure optimized for fast energy diversion during transient events such as load dump or inductive switching spikes.
It meets ISO 7637-2 compliance for automotive electronics and supports steady-state power dissipation of 1 W at 25°C ambient, with derating above TA = 25°C per published curve. Junction temperature range spans –55°C to +150°C, enabling use in under-hood and industrial environments.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 70 V - Maximum continuous reverse operating voltage before leakage exceeds 1 µA; sets safe DC rail margin. |
| VBR @ IT=1 mA | 77.8–86.0 V - Breakdown onset range; ensures reliable triggering above nominal system voltage. |
| VC @ IPPM | 113 V - Clamped voltage at 3.5 A peak impulse; defines worst-case protected circuit voltage during transients. |
| PPPM (10/1000 µs) | 400 W - Peak surge power handling capacity; validates protection against common automotive load dump pulses. |
| IR @ VWM | <1 µA - Reverse leakage at rated stand-off; minimizes standby power loss in battery-backed systems. |
| TJ max | +150°C - Maximum junction temperature; enables operation in high-ambient automotive or industrial enclosures. |
| Package | DO-214AC (SMA) - Industry-standard surface-mount outline; compatible with J-STD-002 soldering and automated pick-and-place. |
Pinout & Package
DO-214AC (SMA) package: molded plastic case with matte tin-plated leads, cathode band marking polarity, MSL Level 1 per J-STD-020, weight ≈0.060 g.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Low-side reference node | Connected to ground or low-voltage return path; forms current path during reverse-biased clamping. |
| Cathode | Protected line input | Connected to DC rail (e.g., 70 V bus); receives transient energy and conducts to anode when V > VBR. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive electronics reliability including temperature cycling, HTRB, and ESD testing per stress test plan. |
| Glass passivated junction | Enhances long-term stability and reduces parameter drift under thermal and humidity stress vs. epoxy-passivated alternatives. |
| Fast response time <1 ps | Ensures clamping activation before sensitive downstream ICs experience overvoltage damage during nanosecond-scale transients. |
| ISO 7637-2 compliant | Guarantees survivability against standardized automotive electrical disturbances including Pulse 1 (inductive switch-off), Pulse 2a/2b (battery disconnect), and Pulse 3a/3b (switching noise). |
| Halogen-free & RoHS | Meets IEC 61249-2-21 and EU RoHS Directive requirements for environmentally restricted substances in final assembly. |
Applications
| Switching Mode Power Supply (SMPS) | Automotive On-Board DC/DC Converter |
|---|---|
Use Scenario: Protects primary-side MOSFET gate drivers and secondary-side rectifiers from flyback-induced voltage spikes during switching transitions. IC Role / Device Role / Timing Role: Unidirectional TVS placed across input/output rails to clamp overshoot exceeding 70 V nominal bus voltage. Use Value: Limits peak rail voltage to ≤113 V during 400 W transients, preventing gate oxide rupture in 100 V-rated FETs and ensuring stable feedback loop operation. | Use Scenario: Shields 12 V/48 V domain converters in ADAS ECUs from load dump surges up to ±120 V per ISO 7637-2 Pulse 5a. IC Role / Device Role / Timing Role: Standoff-rated TVS on converter input side, triggered only during overvoltage events while remaining high-impedance during normal operation. Use Value: Maintains <1 µA leakage at 70 V, avoiding unnecessary quiescent current draw in always-on vehicle modules. |
| Industrial Lighting Driver | Telecom Power Interface |
Use Scenario: Safeguards LED driver ICs and current-sense resistors against inductive kickback from relay-controlled ballasts or dimming circuits. IC Role / Device Role / Timing Role: Fast-clamping unidirectional suppressor placed between HV DC bus and ground, sized for 10/1000 µs surge profile. Use Value: Achieves 113 V clamping at 3.5 A, keeping protected components below absolute maximum ratings even during repetitive 100 ms surges. | Use Scenario: Installed at PoE (Power over Ethernet) front-end to absorb induced surges from cable coupling or lightning-induced ground potential rise. IC Role / Device Role / Timing Role: Primary-level transient protector on 48–57 V DC supply line, coordinated with upstream GDT or MOV for multi-stage protection. Use Value: Provides precise 70 V standoff with tight VBR tolerance (±5.2%), enabling clean separation from upstream protection thresholds without overlap or gap. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ70A | Same VWM (70 V), but lower VBR min (77.8 V) and higher VC (113 V vs. 107 V for SMAJ70H); identical DO-214AC package. | Designed for tighter clamping tolerance in cost-sensitive industrial designs where AEC-Q101 is not required. | Select SMAJ70A if automotive qualification is unnecessary and lower-cost sourcing is prioritized. |
| SMBJ70A | Higher power rating (600 W vs. 400 W), same VWM/VBR range, larger SMB (DO-214AA) package with different pad layout and thermal mass. | Used where higher surge margin is needed and board space allows larger footprint; not drop-in compatible due to package size difference. | Choose SMBJ70A only when 400 W is insufficient and PCB redesign for DO-214AA is acceptable. |
Compared with SMAJ70A and SMBJ70A, the SMAJ70AH uniquely combines AEC-Q101 qualification, MSL Level 1 handling, and precise 113 V clamping in the compact DO-214AC footprint - making it optimal for automotive and space-constrained industrial power rails requiring certified reliability.
Availability
SMAJ70AH is available at Aetrix Electronics and suitable for automotive power management, industrial lighting drivers, telecom power interfaces, and on-board DC/DC converters requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for SMAJ70AH 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 transient protection in automotive and harsh-environment power systems, emphasizing fast response, low leakage, and robust packaging for automated SMT assembly.
FAQ
What is the clamping voltage of SMAJ70AH under standard 10/1000 µs surge conditions?
The SMAJ70AH has a maximum clamping voltage (VC) of 113 V when subjected to its rated peak impulse current of 3.5 A using the 10/1000 µs waveform. This value is measured per JEDEC standards and guarantees that protected circuitry remains below critical overvoltage thresholds during transient events. The SMAJ70AH maintains this clamping performance across its full operating temperature range.
Is SMAJ70AH suitable for bidirectional transient protection?
No, SMAJ70AH is a unidirectional TVS diode intended for DC line protection with defined anode-cathode polarity. For bidirectional applications, Taiwan Semiconductor offers the SMAJ70CH variant (with CH suffix), which provides symmetrical clamping in both directions. Using SMAJ70AH in reverse-biased AC configurations may result in unintended conduction or failure.
Does SMAJ70AH meet automotive qualification standards?
Yes, SMAJ70AH is AEC-Q101 qualified and tested per the full stress test schedule for transient voltage suppressors, including HTGB, HTRB, temperature cycling, and ESD. It also complies with ISO 7637-2 Pulse 1/2a/2b/3a/3b requirements, making it suitable for automotive power electronics such as body control modules and infotainment power supplies.
What is the maximum steady-state power dissipation for SMAJ70AH?
The SMAJ70AH has a maximum steady-state power dissipation (PD) of 1 W at TA = 25°C, with linear derating above that ambient temperature per the published Pulse Derating Curve (Fig.2). This rating applies to continuous DC reverse bias conditions and does not reflect its 400 W peak pulse capability, which is limited to non-repetitive 10/1000 µs events.
How is polarity marked on the SMAJ70AH DO-214AC package?
The SMAJ70AH uses a cathode band (a visible stripe near one end of the DO-214AC body) to indicate the cathode terminal. This band aligns with the cathode lead and must be oriented toward the positive side of the protected DC rail. The anode is the unmarked terminal and connects to ground or circuit return. Correct orientation is essential for proper unidirectional clamping function.
SMAJ70AH 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:
- -
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 150°C (TJ)
- Grade:
- Automotive
- Qualification:
- AEC-Q101
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-214AC (SMA)
SMAJ70AH FAQ
1.How can I place an order for SMAJ70AH through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ70AH 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 SMAJ70AH reliable?
The price and inventory of SMAJ70AH are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ70AH is usually 5 days.
3.What payment methods are accepted for SMAJ70AH?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ70AH transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ70AH?
SMAJ70AH orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ70AH 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 SMAJ70AH?
For technical support, including SMAJ70AH datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ70AH requirements.
6.How does Aetrix verify that SMAJ70AH is sourced from the original manufacturer or authorized distributors?
All SMAJ70AH 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 SMAJ70AH meets industry standards.
7.What is the process for return or replacement of SMAJ70AH?
All SMAJ70AH units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ70AH, 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 SMAJ70AH part is unused and in its original packaging.
Return procedure for SMAJ70AH:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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