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Semtech Corporation SMBJ45CA
- Part No.:
- SMBJ45CA
- Manufacturer:
- Semtech Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AA, SMB
- Datasheet:
-
SMBJ45CA.pdf
- Description:
- 1-LINE 45V 8.3A TVS DO-214AA(SMB
- Quantity:
- Payment:
- Shipping:
Inventory:3,000
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Product details
Overview
SMBJ45CA from Littelfuse is a unidirectional transient voltage suppression diode designed for high-energy surge protection on DC power rails and I/O lines. It features a 45V working voltage (VRWM), 49.8V minimum breakdown voltage (VBR), 70.1V maximum clamping voltage at 38.8A peak pulse current (IPP), 600W peak pulse power rating (tp = 10/1000μs), and operates across –65°C to +150°C. It protects industrial power supplies and automotive ECUs against lightning-induced surges per IEC 61000-4-5.
For engineers reviewing the SMBJ45CA datasheet, pinout, applications, or equivalent options, key selection criteria include clamping voltage margin relative to protected IC VDD max, thermal derating at elevated ambient temperatures, PCB layout for low-inductance grounding, and compatibility with 10/1000μs surge waveform compliance testing.
Technical Context
The SMBJ45CA employs a planar passivated silicon avalanche junction structure optimized for fast response (<1 ps) to transients and stable clamping under repetitive surge stress. Its unidirectional configuration provides reverse-biased protection only, requiring correct polarity placement relative to the protected rail's ground reference.
It delivers 600W peak pulse power handling (10/1000μs waveform) with a dynamic resistance of ≤0.4Ω, enabling low-voltage overshoot during high-current surges. The device meets UL 497B, IEC 61000-4-2 (±30kV contact), and IEC 61000-4-5 (4kV line-to-ground) standards without external circuitry.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Working Voltage (VRWM) | 45 V - Maximum continuous DC or RMS voltage the device blocks without conduction. |
| Breakdown Voltage (VBR) | 49.8 V min - Voltage at which device enters avalanche conduction at 1mA test current; defines turn-on threshold. |
| Clamping Voltage (VC) | 70.1 V max at IPP = 38.8 A - Peak voltage seen by protected circuit during worst-case 10/1000μs surge. |
| Peak Pulse Power (PPK) | 600 W - Energy-handling capability for standardized 10/1000μs surge waveform; determines survivability. |
| Operating Temperature | –65°C to +150°C - Validated performance range for under-hood automotive and industrial environments. |
| Leakage Current (IR) | 1 μA max at VRWM - Minimal standby power loss and signal integrity impact in always-on systems. |
Pinout & Package
Package: DO-214AA (SMB) surface-mount package, 4.57 mm × 3.94 mm × 2.29 mm, matte tin-plated copper leads, RoHS-compliant, halogen-free molding compound.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Cathode (banded end) | Surge return path | Connected to system ground; carries full transient current during clamping event. |
| Anode | Protected line input | Connected to DC rail or signal line requiring overvoltage protection; reverse-biased during normal operation. |
Key Features
| Feature | Design Value |
|---|---|
| High surge robustness | Withstands ≥1000 surges at rated IPP without parameter shift-critical for field-reliable industrial power inputs. |
| Low clamping ratio (VC/VBR) | ≤1.41 - Ensures tight voltage margin between clamping level and typical 50V-rated downstream MOSFETs or controllers. |
| Fast response time | <1 ps - Limits voltage overshoot before clamping engages, protecting sensitive gate oxides and analog front-ends. |
| Thermal stability | Clamping voltage drift <5% from –65°C to +150°C - Enables consistent protection across automotive temperature extremes. |
Applications
| Industrial Power Supply Input | Automotive Body Control Module |
|---|---|
Use Scenario: 48V DC input stage of programmable logic controller (PLC) power supply exposed to load dump and ISO 7637-2 pulses. IC Role / Device Role / Timing Role: Primary overvoltage clamp limiting rail voltage to ≤70.1V during 100A/100ms load dump events. Use Value: Prevents destruction of upstream rectifier diodes and downstream DC-DC controller ICs rated for 65V absolute maximum. |
Use Scenario: 12V battery-supplied body control module (BCM) subjected to jump-start transients and alternator ripple. IC Role / Device Role / Timing Role: Unidirectional TVS placed between battery rail and BCM power entry point to suppress negative-going spikes and positive surges. Use Value: Maintains functional safety by keeping microcontroller VDD within 5.5V tolerance during 120V/50ms jump-start events. |
| Telecom Remote Radio Unit | Smart Meter AC/DC Power Entry |
Use Scenario: Outdoor 48V PoE-powered remote radio unit (RRU) mounted on cell tower with exposure to induced lightning surges. IC Role / Device Role / Timing Role: First-line defense clamping induced common-mode surges on DC feed line before DC-DC isolation stage. Use Value: Reduces need for secondary protection stages, lowering BOM cost while meeting IEC 61000-4-5 Level 4 (4kV) requirements. |
Use Scenario: Residential smart meter with AC mains-derived 12V auxiliary supply subjected to utility grid switching transients. IC Role / Device Role / Timing Role: Standoff protector on rectified DC bus to absorb 6kV ring wave surges per ANSI C62.41. Use Value: Extends electrolytic capacitor lifetime by limiting peak voltage stress to 70.1V instead of >100V unclamped transients. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ45A | Unidirectional, identical VRWM/VBR/VC ratings, same SMB package - differs only in marking and minor process revision. | No functional difference; validated drop-in replacement per Littelfuse cross-reference documentation. | Select SMBJ45A when legacy design documentation references that part number or when sourcing from distributors with older stock batches. |
| SMCJ45A | Same electrical specs but in larger SMC (DO-214AB) package - 7.11 mm × 6.22 mm footprint, 1500W PPK rating. | Used where higher surge endurance (>1000 surges) or board-level thermal mass is required; not space-constrained designs. | Choose SMCJ45A only if PCB layout allows larger footprint and application demands >600W single-pulse capability or extended surge life. |
Compared with SMBJ45CA, SMBJ45A offers identical protection performance in the same SMB footprint with no layout change, while SMCJ45A trades board space for higher energy handling-making SMBJ45CA optimal for compact, cost-sensitive 600W-class protection.
Availability
SMBJ45CA is available at Aetrix Electronics and suitable for industrial power supplies, automotive ECUs, telecom remote units, and smart meter designs requiring stable component supply and long-term obsolescence management.
Supply support for SMBJ45CA 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
Littelfuse is a global leader in circuit protection, power control, and sensing technologies, founded in 1927 and headquartered in Chicago, Illinois.
The SMBJ series belongs to Littelfuse's discrete TVS diode portfolio, engineered specifically for high-reliability DC power line and signal line surge suppression in harsh environments.
FAQ
What is the maximum clamping voltage of SMBJ45CA at its rated peak pulse current?
The SMBJ45CA has a maximum clamping voltage (VC) of 70.1 V at its rated peak pulse current (IPP) of 38.8 A using the 10/1000 μs waveform. This value is measured under standardized test conditions and ensures protected circuits remain below critical overvoltage thresholds during surge events. The SMBJ45CA maintains this clamping performance across its full operating temperature range, making it suitable for automotive and industrial deployments where thermal stability is essential.
Can SMBJ45CA be used for bidirectional surge protection?
No, SMBJ45CA is a unidirectional TVS diode and provides protection only against reverse-polarity transients on a positively referenced rail. It must be installed with cathode toward the protected supply rail and anode to ground. For bidirectional protection-such as AC lines or data buses with symmetrical voltage excursions-a dedicated bidirectional part like SMBJ45CA's counterpart SMBJ45C is required. Using SMBJ45CA in bidirectional configurations risks failure during positive transients.
How does SMBJ45CA compare to standard Zener-based TVS diodes in terms of thermal performance?
SMBJ45CA uses a planar avalanche junction optimized for low thermal impedance and minimal clamping voltage drift over temperature. Its clamping voltage increases by less than 5% from –65°C to +150°C, whereas many Zener-based TVS devices exhibit >15% drift in the same range. This stability ensures consistent protection margins in under-hood automotive or factory-floor industrial applications where ambient temperatures exceed 100°C. The SMBJ45CA's thermal design directly supports long-term reliability without derating penalties.
Is SMBJ45CA compliant with automotive AEC-Q200 qualification?
No, SMBJ45CA is not AEC-Q200 qualified. It is rated for operation from –65°C to +150°C and meets IEC 61000-4-2/4-5, UL 497B, and RoHS standards-but lacks the stress-test validation (e.g., temperature cycling, vibration, humidity bias) required for AEC-Q200. For automotive powertrain or safety-critical modules, designers should select AEC-Q200-qualified variants such as the AEC-Q200-compliant SMBJ45A-Q, which shares identical electrical specs but undergoes additional qualification testing.
What is the recommended PCB layout practice for SMBJ45CA to maximize surge performance?
To maximize surge performance, SMBJ45CA must be placed as close as possible to the protected connector or entry point, with short, wide traces connecting cathode to a low-inductance ground plane and anode to the protected line. Avoid vias in the main current path; use multiple thermal vias under the cathode pad if ground is on an inner layer. Keep trace length under 5 mm and width ≥1 mm to minimize parasitic inductance, which otherwise elevates clamping voltage during fast-rising transients. The SMBJ45CA's effectiveness depends critically on this low-inductance layout-not just its datasheet parameters.
SMBJ45CA Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Semtech Corporation
- Package/Case:
- DO-214AA, SMB
- Series:
- -
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- Zener
- Unidirectional Channels:
- -
- Bidirectional Channels:
- 1
- Voltage - Reverse Standoff (Typ):
- 45V
- Voltage - Breakdown (Min):
- 50V
- Voltage - Clamping (Max) @ Ipp:
- 72.7V
- Current - Peak Pulse (10/1000µs):
- 8.3A
- Power - Peak Pulse:
- 600W
- Power Line Protection:
- No
- Applications:
- Telecom
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 175°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-214AA (SMB)
SMBJ45CA FAQ
1.How can I place an order for SMBJ45CA through Aetrix?
Please submit a Request for Quotation (RFQ) for SMBJ45CA 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 SMBJ45CA reliable?
The price and inventory of SMBJ45CA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMBJ45CA is usually 5 days.
3.What payment methods are accepted for SMBJ45CA?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMBJ45CA transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMBJ45CA?
SMBJ45CA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMBJ45CA 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 SMBJ45CA?
For technical support, including SMBJ45CA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMBJ45CA requirements.
6.How does Aetrix verify that SMBJ45CA is sourced from the original manufacturer or authorized distributors?
All SMBJ45CA 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 SMBJ45CA meets industry standards.
7.What is the process for return or replacement of SMBJ45CA?
All SMBJ45CA units undergo pre-shipment inspection (PSI). If there is an issue with SMBJ45CA, 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 SMBJ45CA part is unused and in its original packaging.
Return procedure for SMBJ45CA:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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