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Taiwan Semiconductor Corporation SMBJ40A
- Part No.:
- SMBJ40A
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AA, SMB
- Datasheet:
-
SMBJ40A.pdf
- Description:
- TVS DIODE 40VWM 64.5VC DO214AA
- Quantity:
- Payment:
- Shipping:
Inventory:113,413
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Product details
Overview
SMBJ40A from Taiwan Semiconductor is a unidirectional surface-mount transient voltage suppressor (TVS) diode designed for high-energy ESD and surge protection in DC power lines and signal paths. It features a 40 V working stand-off voltage (VWM), 44.4–49.1 V breakdown voltage (VBR), 64.5 V maximum clamping voltage (VC) at 9.7 A peak pulse current, and 600 W peak pulse power rating with <1.0 ps response time - deployed in automotive infotainment power rails and industrial I/O modules.
For engineers reviewing the SMBJ40A datasheet, SMBJ40A pinout, SMBJ40A application, or SMBJ40A equivalent, key selection criteria include clamping performance under 10/1000 µs transients, unidirectional polarity marking, DO-214AA (SMB) package thermal resistance (RθJA = 55 °C/W), and compliance with ISO 7637-2 Pulse 1/2a/2b/3a/3b for automotive load-dump immunity.
Technical Context
The SMBJ40A operates as a silicon avalanche diode with glass-passivated junction, enabling fast turn-on during voltage transients while maintaining low leakage (<1 µA at 40 V). Its unidirectional configuration provides forward conduction only on cathode-side overvoltage events, requiring correct PCB polarity alignment relative to protected circuit ground.
Thermal design relies on its DO-214AA package with RθJC = 10 °C/W and RθJA = 55 °C/W, supporting 3 W steady-state dissipation at 25 °C ambient. It meets JESD201 Class 2 whisker resistance and UL 94V-0 flammability standards for reliable long-term mounting in reflow-soldered industrial assemblies.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 40 V - Maximum continuous DC or RMS voltage the device blocks without clamping |
| VBR min/max | 44.4 V / 49.1 V @ 1 mA - Confirmed avalanche onset range defining minimum system overvoltage threshold |
| VC @ IPP | 64.5 V @ 9.7 A - Clamped voltage during 10/1000 µs surge, limiting downstream IC stress to safe levels |
| PPK | 600 W - Peak impulse power handling per single non-repetitive transient event |
| ID @ VWM | <1 µA - Low leakage ensures minimal standby power loss in battery-backed systems |
| TJ max | +150 °C - Maximum junction temperature enabling operation in under-hood automotive environments |
| Response time | <1.0 ps - Sub-nanosecond switching enables protection of high-speed interfaces against ESD |
Pinout & Package
Package: DO-214AA (SMB), surface-mount, cathode-banded unidirectional configuration. Matte tin-plated leads, RoHS and halogen-free compliant, weight ≈ 0.090 g.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Input side of protected line | Connected to supply rail or signal line upstream of sensitive load; conducts during reverse-biased overvoltage |
| Cathode | Ground reference node | Connected to system ground or return path; defines polarity and clamping direction |
| Cathode band | Polarity indicator | Visible marking on package body indicating cathode terminal; critical for correct PCB orientation |
Key Features
| Feature | Design Value |
|---|---|
| Glass-passivated junction | Ensures stable VBR tolerance and long-term reliability under thermal cycling and humidity exposure |
| ISO 7637-2 compliance | Validated for automotive electrical disturbance immunity including load dump (Pulse 2b) and coupled transients (Pulse 3b) |
| J-STD-020 Level 1 moisture sensitivity | Enables standard SMT reflow without baking or special handling prior to assembly |
| UL 94V-0 molding compound | Prevents flame propagation in fault conditions, satisfying safety requirements for industrial enclosures |
| Matte tin plating | Guarantees solderability per J-STD-002 and eliminates whisker growth risk in high-reliability applications |
Applications
| Automotive Power Rail Protection | Industrial PLC Digital I/O Protection |
|---|---|
Use Scenario: Protecting 12 V/24 V power inputs in vehicle infotainment head units from load-dump surges up to 35 V and ISO 7637-2 Pulse 2b. IC Role / Device Role / Timing Role: Unidirectional TVS clamp placed between fused battery input and DC-DC converter input stage. Use Value: Limits transient voltage to ≤64.5 V, preventing damage to downstream buck controller ICs rated for 40 V absolute maximum input. | Use Scenario: Shielding 24 V digital input channels in programmable logic controllers from inductive kickback and EFT bursts. IC Role / Device Role / Timing Role: Front-end surge suppression before optocoupler or Schmitt-trigger input buffer. Use Value: Clamps 1 kV/50 Ω EFT pulses within 1 ps, preserving signal integrity and avoiding false triggering of input latches. |
| LED Driver Power Stage Protection | RS-485 Transceiver Bus Line Protection |
Use Scenario: Safeguarding constant-current LED driver ICs in streetlight controllers exposed to lightning-induced surges on AC/DC front-ends. IC Role / Device Role / Timing Role: Parallel-connected TVS across bulk capacitor input to absorb 600 W transients without derating. Use Value: Maintains VWM = 40 V margin above nominal 36 V LED string voltage, ensuring no false triggering during normal operation. | Use Scenario: Protecting RS-485 transceivers in building automation networks from induced surges on long twisted-pair runs. IC Role / Device Role / Timing Role: Bidirectional protection not applicable; SMBJ40A used on VCC line only, paired with bidirectional TVS on data lines. Use Value: Provides dedicated 40 V rail clamping independent of data-line protection, reducing common-mode stress on transceiver supply pins. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ40CA | Bidirectional variant with symmetrical VBR (44.4–49.1 V) in both polarities; same VWM, VC, and PPK ratings | Required where AC-coupled or floating signal lines need protection against positive and negative transients | Select SMBJ40CA only if bipolar clamping is needed; SMBJ40A is optimal for DC rail protection with defined ground reference |
| SAC40 | Same VWM (40 V) and VC (64.5 V), but lower PPK (400 W); DO-214AC (SMC) package with higher RθJA (65 °C/W) | Acceptable for lower-energy transients or space-constrained designs where SMB footprint is unavailable | Choose SAC40 only when board area allows larger SMC package and surge energy is confirmed ≤400 W |
Compared with SMBJ40CA and SAC40, the SMBJ40A delivers optimal balance of 600 W surge capacity, SMB footprint compatibility, and unidirectional precision for DC power rail protection - making it preferred for automotive and industrial 24 V systems where polarity is fixed and energy levels exceed 400 W.
Availability
SMBJ40A is available at Aetrix Electronics and suitable for automotive infotainment power rails, industrial PLC digital I/O protection, and LED driver power stage protection requiring stable component supply, full traceability, and long-lifecycle support.
Supply support for SMBJ40A 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 SMBJ series was developed specifically for high-reliability transient suppression in automotive and industrial environments, emphasizing ISO 7637-2 compliance, robust thermal performance, and J-STD-020 Level 1 manufacturability.
FAQ
What is the clamping voltage of SMBJ40A under a 10/1000 µs surge?
The SMBJ40A clamps to a maximum of 64.5 V when subjected to a 10/1000 µs waveform at 9.7 A peak pulse current (IPP), as specified in the Electrical Specifications table. This value is measured at TA = 25°C and defines the upper voltage limit imposed on protected circuits during standardized surge events. The SMBJ40A maintains this clamping performance across its operational junction temperature range.
Is SMBJ40A suitable for bidirectional signal line protection?
No, SMBJ40A is a unidirectional TVS diode intended for DC power rail or single-polarity signal protection. For bidirectional applications such as AC-coupled data lines or floating buses, the SMBJ40CA variant must be used instead. The SMBJ40A's cathode band marking and asymmetric IV curve confirm its unidirectional functionality - using it on bidirectional lines risks failure during negative transients.
What is the maximum steady-state power dissipation for SMBJ40A?
The SMBJ40A has a steady-state power dissipation (PD) rating of 3 W at TA = 25°C, as stated in the Absolute Maximum Ratings table. This value decreases linearly with rising ambient temperature per the Pulse Derating Curve (Fig.2). At 85°C ambient, PD drops to approximately 1.7 W. This rating applies only to continuous DC power, not transient surge conditions covered by the 600 W PPK specification.
Does SMBJ40A meet automotive qualification standards?
Yes, SMBJ40A meets ISO 7637-2 test requirements for Pulse 1 (inductive load disconnect), Pulse 2a (sudden load removal), Pulse 2b (supply disconnection), Pulse 3a (capacitive coupling), and Pulse 3b (inductive coupling), as explicitly stated in the FEATURES section. While not AEC-Q200 qualified itself, its electrical and mechanical specifications align with automotive-grade surge immunity testing protocols used in Tier 1 subsystems.
What is the marking code for SMBJ40A on the DO-214AA package?
The marking code for SMBJ40A is "MR", laser-etched or printed on the device body adjacent to the cathode band. This two-character code uniquely identifies the 40 V unidirectional variant within the SMBJ series and is verified in the Electrical Specifications table on page 3 of the Taiwan Semiconductor datasheet (Version R2104). The cathode band serves as the primary polarity indicator during placement.
SMBJ40A Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Taiwan Semiconductor Corporation
- Package/Case:
- DO-214AA, SMB
- Series:
- SMBJ
- 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):
- 9.7A
- Power - Peak Pulse:
- 600W
- 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-214AA (SMB)
SMBJ40A FAQ
1.How can I place an order for SMBJ40A through Aetrix?
Please submit a Request for Quotation (RFQ) for SMBJ40A 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 SMBJ40A reliable?
The price and inventory of SMBJ40A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMBJ40A is usually 5 days.
3.What payment methods are accepted for SMBJ40A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMBJ40A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMBJ40A?
SMBJ40A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMBJ40A 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 SMBJ40A?
For technical support, including SMBJ40A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMBJ40A requirements.
6.How does Aetrix verify that SMBJ40A is sourced from the original manufacturer or authorized distributors?
All SMBJ40A 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 SMBJ40A meets industry standards.
7.What is the process for return or replacement of SMBJ40A?
All SMBJ40A units undergo pre-shipment inspection (PSI). If there is an issue with SMBJ40A, 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 SMBJ40A part is unused and in its original packaging.
Return procedure for SMBJ40A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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