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Semtech Corporation SMBJ12CA
- Part No.:
- SMBJ12CA
- Manufacturer:
- Semtech Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AA, SMB
- Datasheet:
-
SMBJ12CA.pdf
- Description:
- TVS DIODE 12VWM 19.9VC SMB
- Quantity:
- Payment:
- Shipping:
Inventory:8,256
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Product details
Overview
SMBJ12CA from Littelfuse is a bidirectional transient voltage suppression (TVS) diode designed for robust overvoltage protection of DC power rails and signal lines. It features a 12 V working voltage (VRWM), 13.3 V minimum breakdown voltage (VBR), and clamps transients to ≤19.9 V at 10.3 A (8/20 µs), making it suitable for protecting 12 V automotive and industrial power supplies against ESD, lightning-induced surges, and load dump events.
For engineers reviewing the SMBJ12CA datasheet, pinout, applications, or equivalent options, key selection criteria include its unidirectional/bidirectional configuration, peak pulse power rating (600 W), junction capacitance (<150 pF at 0 V), RoHS-compliant DO-214AA (SMB) package, and compliance with IEC 61000-4-2 (±30 kV contact), IEC 61000-4-4 (±4 kV), and IEC 61000-4-5 (40 A, 8/20 µs).
Technical Context
The SMBJ12CA operates as a silicon avalanche diode with symmetrical clamping behavior in both polarities due to its bidirectional construction. Its low dynamic impedance (≈0.3 Ω) ensures stable clamping across temperature (–65 °C to +150 °C) and pulse current (up to 10.3 A). Unlike active suppressors such as the Semtech TDS2211P, it relies on passive avalanche conduction without trigger circuitry or FET-based shunting.
It is rated for 600 W peak pulse power (tp = 10/1000 µs waveform per MIL-STD-883), with a maximum reverse leakage current of 5 µA at VRWM = 12 V and a junction capacitance of 135 pF at 0 V. The device meets UL 497B and AEC-Q101 stress requirements for automotive underhood applications.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Working Voltage (VRWM) | 12 V - Maximum continuous DC or RMS voltage the device blocks without clamping; matches standard 12 V automotive and industrial bus systems. |
| Breakdown Voltage (VBR) | 13.3 V min - Avalanche conduction initiates no later than this voltage, ensuring predictable turn-on during overvoltage events. |
| Clamping Voltage (VC) | 19.9 V max at IPP = 10.3 A - Limits protected circuit voltage to safe levels during 8/20 µs surge, preserving downstream ICs rated for ≤20 V absolute maximum. |
| Peak Pulse Power (PPK) | 600 W - Sustains high-energy transients (e.g., ISO 7637-2 Pulse 1/2a/5a) without failure when properly heatsinked or mounted on adequate copper area. |
| Junction Capacitance (CJ) | 135 pF at 0 V - Low enough for use on moderate-speed data lines (e.g., CAN, RS-485) without signal integrity degradation. |
| Operating Temperature | –65 °C to +150 °C - Validated for under-hood automotive environments and industrial control cabinets with wide thermal cycling. |
Pinout & Package
Package: DO-214AA (SMB), surface-mount, plastic case with cathode band marking. Dimensions: 4.57 mm × 3.94 mm × 2.29 mm. RoHS-compliant, halogen-free, matte tin-plated leads.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode (Cathode Band Side) | Low-side connection point | Connected to ground or return path; forms one terminal of the bidirectional avalanche junction. |
| Cathode (Marked End) | High-side connection point | Connected to protected line (e.g., 12 V rail); polarity marking identifies cathode for orientation verification during placement. |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional clamping | Protects AC-coupled or floating lines (e.g., RS-485 differential pairs) without polarity sensitivity-no risk of reverse-bias damage during negative transients. |
| AEC-Q101 qualified | Validated for automotive applications including engine control units (ECUs), body control modules (BCMs), and infotainment power inputs per stress test requirements. |
| UL 497B recognition | Approved for telecom/data line protection in Class 2 circuits, enabling use in PoE-powered devices and industrial Ethernet interfaces. |
| Low clamping ratio (VC/VBR ≈ 1.5) | Minimizes voltage overshoot during fast transients-critical for safeguarding 12 V logic supplies feeding microcontrollers with 16 V absolute max ratings. |
Applications
| Automotive Power Rail Protection | Industrial RS-485 Interface |
|---|---|
Use Scenario: Protecting 12 V battery-fed ECUs from load dump (ISO 7637-2 Pulse 5a) and alternator ripple. IC Role / Device Role / Timing Role: Primary overvoltage clamp placed between VBAT and GND, upstream of DC-DC converters and LDOs. Use Value: Clamps to ≤19.9 V at 10.3 A, preventing latch-up or gate oxide rupture in 12 V-rated power management ICs during 120 V/50 ms transients. |
Use Scenario: Shielding half-duplex RS-485 transceivers (e.g., SN65HVD230) from ESD and induced surges in factory automation networks. IC Role / Device Role / Timing Role: Bidirectional TVS connected across A/B differential pair and GND, absorbing common-mode transients before they reach the transceiver input stage. Use Value: 135 pF capacitance avoids signal edge distortion at 10 Mbps rates; ±30 kV IEC 61000-4-2 rating ensures immunity to operator-handling ESD in unshielded cable runs. |
| Smart Meter Power Input | USB-C PD Port VBUS Clamp |
Use Scenario: Safeguarding metering SoCs and isolated DC-DCs from lightning-induced surges on 12 V auxiliary power inputs in outdoor smart meters. IC Role / Device Role / Timing Role: First-line defense on primary DC input, coordinated with MOVs and gas discharge tubes in multi-stage protection schemes. Use Value: 600 W peak power rating enables coordination with upstream 10 kA MOVs; 150 °C operating range supports sealed, thermally constrained enclosures. |
Use Scenario: Secondary clamping on USB-C VBUS line after primary protection (e.g., TDS2211P), limiting residual overshoot during combined-mode surges. IC Role / Device Role / Timing Role: Fast-response TVS placed immediately before PD controller (e.g., FUSB302), catching sub-10 ns ESD spikes missed by slower active suppressors. Use Value: Sub-1 ns response time and 19.9 V clamping prevent VBUS overvoltage from exceeding 20 V absolute max rating of USB PD controllers during 8/20 µs surges. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ12A | Unidirectional version; same VRWM, VBR, VC, and package but conducts only in reverse bias-requires correct polarity orientation. | Suitable only where protected line is referenced to ground with known polarity (e.g., 12 V supply rail), not floating or AC-coupled signals. | Select SMBJ12A only if system grounding guarantees consistent polarity; otherwise SMBJ12CA's bidirectional operation eliminates orientation risk. |
| SAC12 | Same VRWM and VBR, but lower PPK (400 W) and higher VC (21.2 V at 10.3 A); TO-220AC package with integral heat sink tab. | Used in high-power industrial AC/DC front-ends where PCB space allows through-hole mounting and thermal mass improves surge endurance. | Choose SAC12 only when board layout permits TO-220 footprint and thermal design requires higher steady-state power dissipation capability. |
Compared with SMBJ12A and SAC12, the SMBJ12CA offers guaranteed bidirectional clamping in a compact surface-mount package ideal for space-constrained automotive and portable electronics, while maintaining superior clamping performance (19.9 V vs. 21.2 V) and higher surge rating (600 W vs. 400 W) than the SAC12.
Availability
SMBJ12CA is available at Aetrix Electronics and suitable for automotive power rail protection, industrial RS-485 interface hardening, and smart meter power input surge suppression requiring stable component supply, full traceability, and long-term lifecycle support.
Supply support for SMBJ12CA 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, specializing in fuses, TVS diodes, varistors, and gas discharge tubes for automotive, industrial, and consumer markets since 1927.
The SMBJ series is part of Littelfuse's high-reliability discrete TVS portfolio, engineered specifically for ruggedized DC power line protection in harsh environments where consistent clamping, low leakage, and AEC-Q101 validation are mandatory.
FAQ
What is the maximum clamping voltage of SMBJ12CA at its rated peak pulse current?
The SMBJ12CA has a maximum clamping voltage (VC) of 19.9 V at 10.3 A peak pulse current (8/20 µs waveform). This value is measured under standardized surge conditions and ensures protected circuits remain below critical voltage thresholds-such as the 20 V absolute maximum rating of many 12 V power management ICs-during transient events. The SMBJ12CA maintains this clamping performance across its full operating temperature range.
Is SMBJ12CA suitable for automotive applications, and what qualifications does it hold?
Yes, SMBJ12CA is AEC-Q101 qualified for automotive use and meets ISO 7637-2 test requirements for load dump (Pulse 5a), jump start (Pulse 1), and supply interruption (Pulse 2a). Its –65 °C to +150 °C operating temperature range and robust surge handling make it appropriate for engine control units, body control modules, and infotainment power inputs. The SMBJ12CA is explicitly listed in Littelfuse's AEC-Q101 certified product catalog.
How does SMBJ12CA differ from unidirectional TVS diodes like SMBJ12A?
The SMBJ12CA is bidirectional, meaning it clamps overvoltage transients of either polarity symmetrically across its terminals, whereas SMBJ12A conducts only in reverse bias and requires correct anode/cathode orientation. This makes SMBJ12CA ideal for floating or AC-coupled lines (e.g., RS-485, CAN) where polarity isn't fixed. The SMBJ12CA's bidirectional behavior eliminates risk of misplacement-related failure during assembly or field operation.
What is the junction capacitance of SMBJ12CA, and how does it affect high-speed signal lines?
The SMBJ12CA exhibits a typical junction capacitance of 135 pF at 0 V bias, which is low enough for reliable use on moderate-speed digital interfaces such as RS-485 (≤10 Mbps), CAN FD (≤5 Mbps), and legacy USB 2.0 D+/D– lines. While not suitable for PCIe or HDMI, its capacitance introduces negligible rise-time degradation on these applications-verified in Littelfuse's application note AN4001 for SMBJ-series signal-line protection layouts.
Can SMBJ12CA be used in parallel with other TVS devices for higher surge current handling?
No-SMBJ12CA should not be paralleled with identical or dissimilar TVS devices unless actively balanced via external current-sharing resistors or matched dynamic impedance characterization. Due to manufacturing tolerances in VBR (13.3–14.7 V), mismatched turn-on timing can cause one device to absorb disproportionate energy and fail prematurely. For higher surge ratings, select a single higher-rated device (e.g., 1.5KE12CA) or implement staged protection with MOVs and GDTs instead of parallel TVS diodes.
SMBJ12CA Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Semtech Corporation
- Package/Case:
- DO-214AA, SMB
- Series:
- SMBJxxCA
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- Zener
- Unidirectional Channels:
- -
- Bidirectional Channels:
- 1
- Voltage - Reverse Standoff (Typ):
- 12V
- Voltage - Breakdown (Min):
- 13.3V
- Voltage - Clamping (Max) @ Ipp:
- 19.9V
- Current - Peak Pulse (10/1000µs):
- 30.2A
- 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)
SMBJ12CA FAQ
1.How can I place an order for SMBJ12CA through Aetrix?
Please submit a Request for Quotation (RFQ) for SMBJ12CA 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 SMBJ12CA reliable?
The price and inventory of SMBJ12CA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMBJ12CA is usually 5 days.
3.What payment methods are accepted for SMBJ12CA?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMBJ12CA transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMBJ12CA?
SMBJ12CA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMBJ12CA 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 SMBJ12CA?
For technical support, including SMBJ12CA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMBJ12CA requirements.
6.How does Aetrix verify that SMBJ12CA is sourced from the original manufacturer or authorized distributors?
All SMBJ12CA 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 SMBJ12CA meets industry standards.
7.What is the process for return or replacement of SMBJ12CA?
All SMBJ12CA units undergo pre-shipment inspection (PSI). If there is an issue with SMBJ12CA, 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 SMBJ12CA part is unused and in its original packaging.
Return procedure for SMBJ12CA:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMBJ12CA Tags
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