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Taiwan Semiconductor Corporation SMBJ40
- Part No.:
- SMBJ40
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AA, SMB
- Datasheet:
-
SMBJ40.pdf
- Description:
- 600W, 49.4V, 10%, UNIDIRECTIONAL
- Quantity:
- Payment:
- Shipping:
Inventory:5,882
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Product details
Overview
SMBJ40 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), 44.4–54.3 V breakdown voltage (VBR), 71.4 V maximum clamping voltage (VC) at 8.8 A peak pulse current, and 600 W peak pulse power rating with <1.0 ps response time. It is used in automotive infotainment power rails to protect downstream DC-DC converters from load dump transients.
For engineers reviewing the SMBJ40 datasheet, SMBJ40 pinout, SMBJ40 application, or SMBJ40 equivalent, key selection criteria include clamping voltage margin relative to protected IC's absolute maximum rating, leakage current at operating voltage, thermal derating above 25°C ambient, and compliance with ISO 7637-2 Pulse 1/2a/2b/3a/3b waveforms.
Technical Context
The SMBJ40 operates as a unidirectional avalanche diode that remains non-conductive below its 40 V working stand-off voltage and clamps sharply above its 44.4–54.3 V breakdown threshold. Its glass-passivated junction ensures stable VBR tolerance and low leakage (<1 µA at 40 V), while its DO-214AA (SMB) package provides 10 °C/W junction-to-case thermal resistance for reliable power dissipation during repetitive surges.
It meets ISO 7637-2 test requirements for automotive electronics, including Pulse 1 (inductive load disconnect), Pulse 2a (sudden load removal), Pulse 2b (supply line interruption), and Pulse 3a/3b (capacitive coupling and ignition noise). Its 150 °C maximum junction temperature and -55 °C to +150 °C storage range support under-hood and industrial control environments.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 40 V - Maximum continuous reverse operating voltage before conduction begins |
| VBR min/max | 44.4 V / 54.3 V - Breakdown occurs within this range at 1 mA test current; defines turn-on threshold window |
| VC @ IPP | 71.4 V at 8.8 A - Clamped voltage during 10/1000 µs surge; must stay below protected IC's max rating |
| PPK | 600 W - Peak pulse power handling per single 10/1000 µs transient |
| ID @ VWM | <1 µA - Reverse leakage at rated stand-off; negligible power loss in standby |
| TJ max | +150 °C - Maximum junction temperature; enables operation in hot environments with proper PCB copper area |
| RθJA | 55 °C/W - Thermal resistance from junction to ambient; guides heatsinking requirements on standard FR-4 |
Pinout & Package
Package: DO-214AA (SMB), surface-mount, single-die unidirectional configuration. Cathode indicated by band marking; anode is unmarked end. Matte tin-plated leads, RoHS and halogen-free compliant.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Low-side reference terminal | Connected to ground or low-voltage rail; completes clamping path during overvoltage event |
| Cathode | High-side surge input terminal | Connected to protected line (e.g., 40 V supply); conducts avalanche current when V > VBR |
Key Features
| Feature | Design Value |
|---|---|
| Fast response time | <1.0 ps - Enables clamping before transient energy couples into sensitive circuitry |
| Glass passivated junction | Stable VBR tolerance and low IR drift over temperature and lifetime |
| ISO 7637-2 compliance | Validated for Pulse 1/2a/2b/3a/3b - Direct qualification for automotive 12 V/24 V system integration |
| Moisture sensitivity level | Level 1 per J-STD-020 - No dry-pack or bake required prior to reflow soldering |
| UL 94V-0 molding compound | Flame-retardant encapsulation - Meets safety standards for enclosed industrial modules |
Applications
| Automotive Power Rail Protection | Industrial Sensor Interface Protection |
|---|---|
Use Scenario: Protecting 40 V DC power input of vehicle telematics module against load dump and jump-start transients. IC Role / Device Role / Timing Role: Unidirectional TVS placed between input rail and chassis ground to shunt surge current away from DC-DC controller and LDOs. Use Value: Limits clamped voltage to 71.4 V, staying 18.6 V below typical 90 V automotive IC absolute maximum rating, preventing latch-up or oxide damage. | Use Scenario: Safeguarding RS-485 transceiver I/O pins in factory automation PLCs exposed to EFT bursts. IC Role / Device Role / Timing Role: Bidirectional protection not applicable; SMBJ40 used only on DC supply side of transceiver, not signal lines. Use Value: Sub-µA leakage at 40 V ensures no impact on 24 V sensor loop accuracy; 600 W rating absorbs multiple 1 kV/50 Ω EFT pulses without degradation. |
| LED Driver Input Protection | Medical Equipment DC Supply Protection |
Use Scenario: Shielding constant-current LED driver IC from inductive switching spikes generated by nearby relay coils. IC Role / Device Role / Timing Role: TVS connected across input capacitor to clamp fast-rising transients before they reach driver's VIN pin. Use Value: 71.4 V clamping voltage prevents overstress on 75 V-rated input capacitors and internal FETs; DO-214AA footprint allows compact layout near connector. | Use Scenario: Guarding isolated 40 V auxiliary supply in diagnostic imaging equipment against mains-coupled surges. IC Role / Device Role / Timing Role: Primary overvoltage suppression device on secondary-side DC bus, upstream of isolation barrier monitoring circuitry. Use Value: UL 94V-0 package and halogen-free construction meet IEC 60601-1 flammability and toxicity requirements; 150 °C TJ rating supports sealed enclosure thermal profiles. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ40A | Narrower VBR range (44.4–49.1 V) and lower VC (64.5 V at 9.7 A); tighter tolerance improves clamping predictability | Better suited for systems where margin to IC absolute max rating is ≤10 V; same DO-214AA footprint | Select SMBJ40A when clamping voltage headroom is critical and tighter VBR distribution reduces design margin uncertainty |
| SAC40 | Same VWM (40 V) but higher PPK (1500 W); larger DO-214AB (SMC) package; higher IPP (22 A) | Required for higher-energy transients (e.g., ISO 7637-2 Pulse 5a); needs larger PCB pad area and thermal relief | Choose SAC40 only if 600 W is insufficient per system-level surge testing; not drop-in due to package and thermal profile differences |
Compared with SMBJ40, the SMBJ40A offers tighter VBR control and lower clamping voltage for improved precision protection, while the SAC40 delivers triple the surge power handling in a physically larger package-neither is pin-compatible, but both serve overlapping automotive and industrial surge categories with distinct trade-offs in size, clamping performance, and energy capacity.
Availability
SMBJ40 is available at Aetrix Electronics and suitable for automotive infotainment power rails, industrial sensor interface protection, and LED driver input circuits requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for SMBJ40 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 robust, high-reliability transient suppression in automotive and industrial environments, emphasizing ISO 7637-2 compliance, tight parametric consistency, and automated assembly compatibility.
FAQ
What is the maximum clamping voltage of SMBJ40 under standard 10/1000 µs surge conditions?
The SMBJ40 has a maximum clamping voltage (VC) of 71.4 V when subjected to an 8.8 A peak impulse current with a 10/1000 µs waveform. This value is measured per ANSI/IEEE C62.35 and appears in Taiwan Semiconductor's official SMBJ series datasheet (R2104, Page 3). It defines the upper voltage limit imposed on the protected circuit during worst-case transient events, and must be verified against the absolute maximum ratings of downstream components in the SMBJ40 application.
Is SMBJ40 suitable for bidirectional transient protection?
No, SMBJ40 is a unidirectional TVS diode and is not rated for bidirectional operation. For bipolar protection, Taiwan Semiconductor specifies the SMBJ40C or SMBJ40CA variants, which feature symmetrical breakdown in both directions. The SMBJ40 datasheet explicitly states polarity marking (cathode band) and lists electrical characteristics only for reverse-biased operation; using SMBJ40 in AC or dual-polarity signal paths may result in forward conduction failure or permanent damage.
What is the leakage current specification for SMBJ40 at its working stand-off voltage?
The SMBJ40 exhibits a maximum blocking leakage current (ID) of 1 µA when biased at its 40 V working stand-off voltage (VWM), tested at TA = 25°C. This value is confirmed in the Electrical Specifications table (Page 3, R2104) and reflects minimal power loss in normal operation-critical for battery-powered or low-quiescent-current systems. Leakage remains well below 1 µA up to 40 V and rises sharply only near VBR.
Does SMBJ40 comply with automotive surge immunity standards?
Yes, SMBJ40 meets ISO 7637-2 requirements for Pulses 1, 2a, 2b, 3a, and 3b, as documented in the Features section (Page 1, R2104). These pulses simulate real-world automotive transients including load dump, alternator regulation faults, and inductive switching noise. Compliance is inherent to the device's 600 W PPK rating, sub-1 ps response, and validated clamping behavior-not dependent on external circuitry-and applies directly to the SMBJ40 part number as shipped.
What is the thermal resistance from junction to ambient for SMBJ40 in standard mounting conditions?
The SMBJ40 has a junction-to-ambient thermal resistance (RθJA) of 55 °C/W when mounted on a standard FR-4 PCB with minimum recommended copper land pattern per the DO-214AA outline (Page 7, R2104). This value assumes no additional heatsinking; actual thermal performance improves with increased copper area or thermal vias. The SMBJ40's 150 °C maximum junction temperature and 55 °C/W RθJA allow it to sustain repeated 600 W surges in ambient temperatures up to 85 °C with appropriate board layout.
SMBJ40 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:
- 71.4V
- Current - Peak Pulse (10/1000µs):
- 8.8A
- 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)
SMBJ40 FAQ
1.How can I place an order for SMBJ40 through Aetrix?
Please submit a Request for Quotation (RFQ) for SMBJ40 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 SMBJ40 reliable?
The price and inventory of SMBJ40 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMBJ40 is usually 5 days.
3.What payment methods are accepted for SMBJ40?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMBJ40 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMBJ40?
SMBJ40 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMBJ40 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 SMBJ40?
For technical support, including SMBJ40 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMBJ40 requirements.
6.How does Aetrix verify that SMBJ40 is sourced from the original manufacturer or authorized distributors?
All SMBJ40 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 SMBJ40 meets industry standards.
7.What is the process for return or replacement of SMBJ40?
All SMBJ40 units undergo pre-shipment inspection (PSI). If there is an issue with SMBJ40, 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 SMBJ40 part is unused and in its original packaging.
Return procedure for SMBJ40:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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