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Taiwan Semiconductor Corporation SMAJ40AH
- Part No.:
- SMAJ40AH
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ40AH.pdf
- Description:
- TVS DIODE 40VWM 64.5VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:5,438
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Product details
Overview
SMAJ40AH from Taiwan Semiconductor is a unidirectional surface-mount transient voltage suppressor (TVS) diode designed for robust overvoltage protection in DC power rails. It features a 40 V working stand-off voltage (VWM), 44.4–49.1 V breakdown voltage (VBR), and clamps to ≤64.5 V at 6.2 A peak impulse current under 10/1000 µs waveform - ideal for protecting automotive-grade DC/DC converters and industrial SMPS inputs.
For engineers reviewing the SMAJ40AH datasheet, SMAJ40AH pinout, SMAJ40AH application, or SMAJ40AH equivalent, key selection criteria include its AEC-Q101 qualification, DO-214AC (SMA) package compatibility with automated placement, low leakage (<1 µA @ 40 V), and ISO 7637-2 Pulse 1/2a/2b/3a/3b compliance for automotive transients.
Technical Context
The SMAJ40AH operates as a unidirectional avalanche diode, leveraging glass-passivated junction technology for stable breakdown behavior and fast response (<1.0 ps from 0 V to VBR min). Its clamping action begins at VBR and limits transient energy by diverting surge current to ground while maintaining system-side voltage below 64.5 V.
Rated for 400 W peak pulse power (10/1000 µs), it delivers 6.2 A maximum peak impulse current (IPPM) and supports continuous operation up to +150 °C junction temperature. The device meets JESD201 Class 2 whisker resistance and UL 94V-0 flammability requirements in its DO-214AC molded package.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 40 V - Maximum continuous reverse operating voltage before significant leakage; defines safe DC rail margin. |
| VBR @ IT=1 mA | 44.4–49.1 V - Breakdown onset range; ensures reliable triggering above nominal 40 V supply. |
| VC @ IPPM=6.2 A | ≤64.5 V - Clamped voltage during 10/1000 µs surge; determines protected circuit's maximum stress level. |
| PPPM | 400 W - Peak pulse power handling; enables suppression of high-energy transients per ISO 7637-2. |
| IR @ VWM | <1 µA - Reverse leakage at rated stand-off; minimizes standby power loss in battery-critical systems. |
| TJ max | +150 °C - Maximum junction temperature; supports under-hood automotive and high-ambient industrial use. |
Pinout & Package
DO-214AC (SMA) surface-mount package: cathode-banded single-ended configuration with matte tin-plated leads, compliant with J-STD-002 solderability and JESD201 Class 2 whisker resistance. Weight ≈ 0.060 g.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Input/Line side (cathode-banded end is cathode) | Connected to protected line; conducts surge current toward ground when clamping. |
| Cathode | Ground reference / return path | Marked by band; ties to system ground or low-impedance return to complete clamping loop. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive electronics per stress test requirements - enables use in engine control, body electronics, and ADAS power rails. |
| Glass-passivated junction | Ensures stable VBR tolerance and long-term reliability under thermal cycling and humidity exposure. |
| Fast response time <1.0 ps | Clamps ESD and fast transients before sensitive downstream ICs experience overstress. |
| ISO 7637-2 compliance (Pulse 1/2a/2b/3a/3b) | Meets full suite of automotive load-dump and switching transient immunity standards without external filtering. |
Applications
| Automotive On-Board DC/DC Converter | Industrial Switching Mode Power Supply (SMPS) |
|---|---|
Use Scenario: Protecting 48 V input stage of a buck converter powering ADAS sensors in vehicle chassis modules. IC Role / Device Role / Timing Role: Unidirectional TVS placed between input rail and chassis ground to clamp load-dump spikes up to ±100 V. Use Value: Limits voltage seen by controller IC to ≤64.5 V during ISO 7637-2 Pulse 5a events, preventing latch-up or gate oxide damage. | Use Scenario: Input-stage surge protection for a 36–75 V telecom rectifier feeding FPGA-based baseband processing. IC Role / Device Role / Timing Role: Standoff-rated TVS absorbing repetitive 400 W surges from AC line transients and inductive switching noise. Use Value: Maintains <1 µA leakage at 40 V nominal, avoiding efficiency loss in high-efficiency (>94%) SMPS designs. |
| LED Driver Power Input | Medical Grade AC/DC Adapter |
Use Scenario: Safeguarding constant-current LED driver ICs against induced surges in outdoor streetlight installations. IC Role / Device Role / Timing Role: Primary-side TVS on 48 V bus, triggered by lightning-induced ring waves on long cable runs. Use Value: Withstands 6.2 A peak impulse current and recovers fully within nanoseconds - no degradation after repeated 10/1000 µs events. | Use Scenario: Secondary-side transient suppression in isolated 24 V output adapter for patient-monitoring equipment. IC Role / Device Role / Timing Role: Low-leakage unidirectional TVS ensuring no DC bias shift on safety-isolated output rail. Use Value: Complies with IEC 61249-2-21 halogen-free and RoHS directives - required for medical device material declarations. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ40A | Same VWM/VBR/VC specs but not AEC-Q101 qualified; lower production screening. | Limited to commercial/industrial use; unsuitable for automotive OEM programs requiring AEC validation. | Select SMAJ40A only if automotive qualification is unnecessary and cost sensitivity outweighs long-term field reliability needs. |
| SMBJ40AH | Same electrical specs but in larger DO-214AA (SMB) package; 600 W PPPM rating. | Better thermal dissipation for high-repetition surges; requires PCB layout change due to 4.6 mm × 3.6 mm footprint vs. SMA's 4.2 mm × 2.6 mm. | Choose SMBJ40AH when surge duty cycle exceeds 1 Hz or ambient temperature exceeds 105 °C - otherwise SMAJ40AH offers optimal space efficiency. |
Compared with SMAJ40A and SMBJ40AH, the SMAJ40AH uniquely balances AEC-Q101 compliance, DO-214AC space efficiency, and 400 W transient handling - making it the preferred choice for automotive and space-constrained industrial DC/DC front ends where qualification and footprint are jointly critical.
Availability
SMAJ40AH is available at Aetrix Electronics and suitable for automotive on-board DC/DC converters, industrial switching mode power supplies, and LED driver power inputs requiring stable component supply across extended temperature ranges and long product lifecycles.
Supply support for SMAJ40AH 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 high-reliability protection devices and power management components.
The SMAJ series was developed specifically for automotive and industrial transient suppression, emphasizing AEC-Q101 qualification, ISO 7637-2 compliance, and robust glass-passivated junction performance in compact surface-mount packages.
FAQ
What is the clamping voltage of SMAJ40AH at its rated peak pulse current?
The SMAJ40AH clamps to a maximum of 64.5 V when subjected to its rated peak impulse current of 6.2 A under the standard 10/1000 µs waveform. This value is measured per JEDEC test conditions and guarantees that downstream circuitry remains below this voltage threshold during transient events - a critical parameter for safeguarding 48 V-rated controllers and gate drivers. The SMAJ40AH maintains this clamping performance across its full operating temperature range of −55 °C to +150 °C.
Is SMAJ40AH suitable for bidirectional transient protection?
No, SMAJ40AH is a unidirectional TVS diode, intended only for DC circuits with defined polarity. Its cathode band marks the ground-reference terminal, and it does not conduct in reverse beyond VWM. For bidirectional protection - such as AC lines or differential data buses - a bipolar variant like SMAJ40CH (with CH suffix) must be used instead. The SMAJ40AH datasheet explicitly states electrical characteristics apply in one direction only, and using it in reverse-biased AC applications risks permanent failure.
Does SMAJ40AH meet automotive qualification standards?
Yes, SMAJ40AH is AEC-Q101 qualified and tested per the full stress test schedule including HTGB, HTRB, TCT, and mechanical shock. It also complies with ISO 7637-2 Pulse 1, 2a, 2b, 3a, and 3b for automotive transient immunity. These qualifications are documented in Taiwan Semiconductor's official A2102 revision datasheet and verified through third-party lab reports - confirming suitability for engine control units, infotainment power supplies, and ADAS domain controllers.
What is the maximum steady-state power dissipation for SMAJ40AH?
The SMAJ40AH has a maximum steady-state power dissipation (PD) of 1 W at 25 °C ambient, derating linearly above that temperature per the published derating curve (Fig.2). This rating applies only to continuous DC power - not transient pulses. In normal operation, the device draws less than 1 µA leakage at 40 V, resulting in sub-40 µW static power loss. The 1 W limit becomes relevant only during sustained overvoltage faults exceeding VWM, where thermal shutdown or system-level protection should intervene before reaching this limit.
How does the SMAJ40AH differ from the SMAJ40H variant?
The SMAJ40AH has a tighter breakdown voltage range (44.4–49.1 V) compared to SMAJ40H (44.4–54.3 V), achieved via enhanced process control. This narrower VBR distribution improves design margin predictability in safety-critical applications. Both share identical VWM (40 V), VC (64.5 V / 71.4 V), and packaging, but only SMAJ40AH carries AEC-Q101 qualification. The "A" suffix denotes the higher consistency grade - confirmed in Taiwan Semiconductor's A2102 datasheet Table 1 and ordering code documentation.
SMAJ40AH 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):
- 40V
- Voltage - Breakdown (Min):
- 44.4V
- Voltage - Clamping (Max) @ Ipp:
- 64.5V
- Current - Peak Pulse (10/1000µs):
- 6.2A
- 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)
SMAJ40AH FAQ
1.How can I place an order for SMAJ40AH through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ40AH 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 SMAJ40AH reliable?
The price and inventory of SMAJ40AH are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ40AH is usually 5 days.
3.What payment methods are accepted for SMAJ40AH?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ40AH transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ40AH?
SMAJ40AH orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ40AH 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 SMAJ40AH?
For technical support, including SMAJ40AH datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ40AH requirements.
6.How does Aetrix verify that SMAJ40AH is sourced from the original manufacturer or authorized distributors?
All SMAJ40AH 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 SMAJ40AH meets industry standards.
7.What is the process for return or replacement of SMAJ40AH?
All SMAJ40AH units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ40AH, 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 SMAJ40AH part is unused and in its original packaging.
Return procedure for SMAJ40AH:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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