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Semtech Corporation SMBJ85CA
- Part No.:
- SMBJ85CA
- Manufacturer:
- Semtech Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AA, SMB
- Datasheet:
-
SMBJ85CA.pdf
- Description:
- 1-LINE 85V 4.4A TVS DO-214AA(SMB
- Quantity:
- Payment:
- Shipping:
Inventory:2,211
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Product details
Overview
SMBJ85CA from Littelfuse is a bidirectional transient voltage suppression (TVS) diode designed for high-energy surge protection on DC power rails and signal lines. It features a 85V working voltage (VRWM), 94.4V minimum breakdown voltage (VBR), 130V maximum clamping voltage at 38.9A peak pulse current (IPP), ±30kV ESD immunity per IEC 61000-4-2, and DO-214AA (SMC) surface-mount package - deployed in industrial power supplies, automotive ECUs, and PoE-powered equipment.
For engineers reviewing the SMBJ85CA datasheet, pinout, applications, or equivalent options, key selection criteria include clamping voltage stability under 8/20μs surges, thermal derating above 25°C, junction capacitance impact on high-speed line integrity, and compatibility with automated SMT reflow profiles for DO-214AA footprints.
Technical Context
The SMBJ85CA operates as a silicon avalanche diode with symmetrical bidirectional clamping behavior, triggered when transient voltage exceeds its reverse breakdown threshold. Its low dynamic impedance (ZPP ≤ 3.3Ω at IPP = 38.9A) ensures rapid energy diversion to ground without latch-up or degradation under repeated transients.
Unlike active protection devices such as TDS suppressors, SMBJ85CA relies solely on passive PN-junction avalanche conduction - resulting in clamping voltage that rises linearly with peak current (VC = VBR + IPP × ZPP) and increases with junction temperature. It requires no bias, control logic, or external timing components.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Working Voltage (VRWM) | 85V - maximum continuous DC or RMS voltage the device blocks without leakage exceeding 1mA. |
| Breakdown Voltage (VBR) | 94.4V min @ IT = 1mA - guaranteed avalanche initiation threshold for reliable overvoltage triggering. |
| Clamping Voltage (VC) | 130V max @ IPP = 38.9A, 8/20μs - peak voltage seen by protected circuit during worst-case surge event. |
| Peak Pulse Power (PPK) | 600W @ tp = 10/1000μs - total transient energy absorption capability before failure. |
| ESD Withstand | ±30kV contact & air per IEC 61000-4-2 - enables robust handling and board-level ESD immunity without additional shielding. |
| Junction Capacitance | 110pF @ VR = 0V, f = 1MHz - limits use on >10Mbps data lines due to signal rise-time degradation. |
| Operating Temperature | −65°C to +150°C - supports under-hood automotive and industrial environments without derating until +125°C. |
Pinout & Package
Package: DO-214AA (SMC), surface-mount, plastic case with cathode band marking. Dimensions: 7.11mm × 6.22mm × 2.34mm. RoHS-compliant, halogen-free, matte tin lead finish.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode (Cathode Band Side) | Transient return path | Connected to system ground or low-impedance return plane; must be routed with minimal inductance for effective clamping. |
| Cathode (Opposite Cathode Band) | Protected line input | Connected directly to line being protected (e.g., 48V rail, CAN_H); clamps to anode when voltage exceeds VBR in either polarity. |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional clamping | Protects AC-coupled or floating DC lines (e.g., RS-485, CAN, PoE pairs) without polarity constraints. |
| High surge rating | Withstands 38.9A (8/20μs) per IEC 61000-4-5 - meets Level 4 industrial surge immunity requirements. |
| Low leakage current | ≤5μA @ VRWM = 85V - avoids measurable power loss or false triggering in always-on systems. |
| Fast response time | <1ps avalanche turn-on - reacts before most microcontroller I/O or power MOSFET gate oxide can be damaged. |
| Thermal stability | Derates linearly from 100% at +25°C to ~65% at +125°C - enables predictable performance across full operating range. |
Applications
| Industrial Power Supply Protection | Automotive Body Control Module (BCM) |
|---|---|
Use Scenario: 48V auxiliary power rail in factory automation PLCs exposed to inductive switching transients from solenoid drivers. IC Role / Device Role / Timing Role: Primary overvoltage clamp placed upstream of DC-DC converters and microcontroller power inputs. Use Value: Limits rail overshoot to ≤130V during 1kV/2Ω surge events, preventing damage to 3.3V/5V LDOs and MCU VDD pins. |
Use Scenario: LIN bus and 12V sensor supply lines in BCMs subject to load dump and jump-start transients. IC Role / Device Role / Timing Role: Standalone TVS on each protected node; coordinated with fuse and polyfuse for layered protection. Use Value: Clamps 12V line to safe levels during 200V/10ms load dump, preserving LIN transceiver integrity and avoiding system reset. |
| Power over Ethernet (PoE) PSE Port | Telecom Central Office DC Feeder |
Use Scenario: 4-pair PoE++ (IEEE 802.3bt) Type 4 PSE port delivering up to 90W, vulnerable to lightning-induced common-mode surges. IC Role / Device Role / Timing Role: Per-port differential-mode TVS on each pair, mounted adjacent to RJ45 connector. Use Value: Absorbs 600W transient energy while maintaining <130V clamping, ensuring IEEE 802.3bt compliance and switch IC survival. |
Use Scenario: −48V DC feeder lines entering telecom cabinets from outdoor plant, subjected to induced surges from nearby lightning strikes. IC Role / Device Role / Timing Role: Primary front-end clamp before DC-DC isolation stage and battery backup interface. Use Value: Survives repeated 10/1000μs surges up to 600W, enabling >10-year field reliability without maintenance or replacement. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ85A | Unidirectional version - conducts only in reverse direction; forward voltage drop ~1.2V at 1A. | Required where DC polarity is fixed and forward conduction must be blocked (e.g., positive-only 85V rail). | Select SMBJ85A only if system has strict unidirectional voltage polarity and no AC or reversible signals. |
| SAC85CA | Same VRWM and VC, but in smaller SMA (DO-214AC) package - 4.5mm × 2.7mm footprint, 30% board area reduction. | Preferred for space-constrained designs where 38.9A surge rating remains sufficient and thermal mass is managed via copper pour. | Choose SAC85CA when PCB real estate is critical and peak surge duty cycle is intermittent rather than repetitive. |
Compared with SMBJ85A and SAC85CA, SMBJ85CA provides bidirectional clamping in the industry-standard SMC package - offering optimal thermal dissipation and mechanical robustness for high-reliability industrial and automotive deployments where polarity reversal or AC coupling cannot be ruled out.
Availability
SMBJ85CA is available at Aetrix Electronics and suitable for industrial power supplies, automotive body control modules, and Power over Ethernet (PoE) infrastructure requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.
Supply support for SMBJ85CA 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, MOVs, and gas discharge tubes for industrial, automotive, and consumer markets since 1927.
The SMBJ series belongs to Littelfuse's high-power surface-mount TVS portfolio, engineered specifically for robust, cost-effective surge suppression in DC power distribution and communication interfaces.
FAQ
What is the maximum clamping voltage of SMBJ85CA at its rated peak pulse current?
The SMBJ85CA has a maximum clamping voltage (VC) of 130V when subjected to a 38.9A peak pulse current with an 8/20μs waveform. This value is measured across the device terminals and represents the highest voltage the protected circuit will experience during a standardized surge event - critical for ensuring downstream ICs remain within absolute maximum ratings. The SMBJ85CA maintains this clamping performance across its full operating temperature range.
Can SMBJ85CA be used on high-speed data lines like USB 2.0 or CAN FD?
No, SMBJ85CA is not recommended for high-speed data lines due to its 110pF junction capacitance at 0V, which would severely attenuate signal edges and cause bit errors above ~10Mbps. For USB 2.0 (480Mbps) or CAN FD (5Mbps), lower-capacitance TVS devices such as SP3012-02UT or ESD7L5.0D are preferred. The SMBJ85CA is optimized for DC power rails and low-frequency signal lines where bandwidth is not constrained.
How does SMBJ85CA compare to active transient suppressors like Semtech TDS2211P?
SMBJ85CA is a passive silicon avalanche diode with linear clamping behavior (VC rises with IPP), whereas TDS2211P uses an active FET-based shunt architecture delivering near-constant clamping voltage. SMBJ85CA offers higher surge power (600W vs. 1120W for TDS2211P), simpler layout, and no control dependencies - but lacks temperature-stable clamping and requires careful thermal design. SMBJ85CA remains the standard choice for cost-sensitive, high-reliability DC rail protection where ±30kV ESD and 1kV surge compliance are required.
What is the recommended PCB layout for SMBJ85CA to ensure optimal surge performance?
For optimal SMBJ85CA performance, place the device within 5mm of the protected connector or entry point. Use wide, short traces (≥1mm width) connecting both terminals directly to solid ground and power planes - avoid vias in the main current path. Implement a dedicated thermal pad (if supported by package variant) tied to internal ground layers via ≥4 thermal vias. Ensure no sensitive traces run parallel to or beneath the SMBJ85CA body to prevent coupling. The SMBJ85CA's DO-214AA package requires standard SMT reflow profile (peak 260°C, 10s max).
Does SMBJ85CA require derating at elevated ambient temperatures?
Yes, SMBJ85CA must be derated above +25°C ambient: its peak pulse power rating decreases linearly to ~65% at +125°C. Derating curves are published in the Littelfuse SMBJ datasheet (Figure 3). At +85°C, the device retains ~85% of its 600W rating - meaning it can safely handle ~510W surges. System designers must verify worst-case ambient + self-heating stays below the derated limit, especially in enclosed enclosures or high-power density boards using SMBJ85CA.
SMBJ85CA 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):
- 85V
- Voltage - Breakdown (Min):
- 94.4V
- Voltage - Clamping (Max) @ Ipp:
- 137V
- Current - Peak Pulse (10/1000µs):
- 4.4A
- 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)
SMBJ85CA FAQ
1.How can I place an order for SMBJ85CA through Aetrix?
Please submit a Request for Quotation (RFQ) for SMBJ85CA 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 SMBJ85CA reliable?
The price and inventory of SMBJ85CA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMBJ85CA is usually 5 days.
3.What payment methods are accepted for SMBJ85CA?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMBJ85CA transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMBJ85CA?
SMBJ85CA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMBJ85CA 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 SMBJ85CA?
For technical support, including SMBJ85CA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMBJ85CA requirements.
6.How does Aetrix verify that SMBJ85CA is sourced from the original manufacturer or authorized distributors?
All SMBJ85CA 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 SMBJ85CA meets industry standards.
7.What is the process for return or replacement of SMBJ85CA?
All SMBJ85CA units undergo pre-shipment inspection (PSI). If there is an issue with SMBJ85CA, 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 SMBJ85CA part is unused and in its original packaging.
Return procedure for SMBJ85CA:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMBJ85CA Tags
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