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Diodes Incorporated 1SMB5945B-13
- Part No.:
- 1SMB5945B-13
- Manufacturer:
- Diodes Incorporated
- Category:
- Single Zener Diodes
- Package:
- DO-214AA, SMB
- Datasheet:
-
1SMB5945B-13.pdf
- Description:
- DIODE ZENER 68V 3W SMB
- Quantity:
- Payment:
- Shipping:
Inventory:2,038
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Product details
Overview
1SMB5945B-13 from Diodes Incorporated is a 3.0W surface-mount power Zener diode with a nominal zener voltage of 68V (±5% tolerance), 5.5mA test current, and 1700Ω dynamic impedance at IZT; it provides precision voltage regulation in DC power rails and overvoltage protection circuits for industrial power supplies.
For engineers reviewing the 1SMB5945B-13 datasheet, 1SMB5945B-13 pinout, 1SMB5945B-13 application, or 1SMB5945B-13 equivalent, key selection criteria include zener voltage accuracy, thermal resistance (RθJA = 226°C/W), power derating above +25°C, and ESD robustness (Class 3, >16kV HBM).
Technical Context
This device operates as a two-terminal voltage reference, clamping reverse-biased voltage at 68V with low dynamic impedance (1700Ω at 5.5mA) and minimal temperature coefficient drift. It maintains stable regulation under transient load conditions due to its 3.0W power dissipation rating at TL = +75°C.
Designed for surface-mount assembly on FR-4 PCBs using Diodes Inc.'s AP02001 pad layout, it features a molded SMB plastic case (UL 94V-0), cathode band polarity marking, and lead-free matte tin plating compliant with RoHS 3 and halogen/antimony-free "Green" standards.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 68V nominal, ±5% tolerance - ensures precise clamping within 64.6–71.4V range at 5.5mA test current |
| Power Dissipation (PD) | 3.0W at TL = +75°C - supports high-energy transient suppression without thermal runaway when properly heatsinked |
| Zener Impedance (ZZT) | 1700Ω at IZT = 5.5mA - indicates moderate regulation stiffness suitable for non-critical reference applications |
| Thermal Resistance (RθJA) | 226°C/W - requires careful PCB copper area design to maintain junction temperature below +150°C in ambient up to +75°C |
| ESD Rating | Class 3 (>16kV HBM) - enables robust handling in automated SMT lines without additional ESD mitigation |
| Reverse Leakage (IR) | 0.25µA max at VR = 51.7V - guarantees negligible standby current in high-impedance bias networks |
Pinout & Package
Package: SMB (Surface Mount Small Outline), molded plastic case with UL 94V-0 flammability rating, cathode band polarity marking, and 0.096g mass. Dimensions: 3.30–3.94mm (A) × 4.06–4.57mm (B) × 1.96–2.21mm (C).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction terminal / low-side connection | Connected to circuit ground or lower potential node during normal operation; carries forward current up to 200mA |
| Cathode | Zener breakdown terminal / high-side connection | Connected to regulated rail or protected node; sustains reverse breakdown at 68V with controlled dynamic impedance |
Key Features
| Feature | Design Value |
|---|---|
| 3.0W power rating at TL = +75°C | Enables use in higher-energy surge suppression where standard 1W Zeners would fail thermally |
| ±5% VZ tolerance | Provides predictable clamping threshold without requiring post-production trimming or binning |
| ESD Class 3 (>16kV HBM) | Eliminates need for external ESD protection during board assembly and field handling |
| RoHS 3 & "Green" compliant | Meets global environmental compliance requirements including Br+Cl <1500ppm and Sb <1000ppm |
Applications
| Industrial Power Supply Regulation | Automotive ECU Overvoltage Clamp |
|---|---|
Use Scenario: Stabilizing auxiliary 68V DC bus in programmable logic controller (PLC) power modules. IC Role / Device Role / Timing Role: Two-terminal shunt regulator maintaining output voltage within ±5% despite input ripple and load transients. Use Value: Prevents downstream 68V-rated controllers from brownout or overvoltage damage during line surges. | Use Scenario: Protecting CAN transceiver supply rail against load-dump transients in 24V commercial vehicle ECUs. IC Role / Device Role / Timing Role: Fast-acting voltage clamp limiting rail excursion to ≤71.4V during ISO 7637-2 Pulse 5a events. Use Value: Avoids destructive latch-up in 68V-tolerant CAN PHY ICs without adding series resistance or delay. |
| Telecom Line Card Surge Protection | Test Equipment Reference Calibration |
Use Scenario: Secondary overvoltage protection on -48V telecom line card outputs exposed to lightning-induced surges. IC Role / Device Role / Timing Role: Standby shunt element activated only during >68V transients, minimizing quiescent power loss. Use Value: Adds fail-safe clamping layer behind primary TVS diodes while preserving low standby current (<0.25µA). | Use Scenario: Providing stable 68V reference for calibration of high-voltage multimeters and insulation testers. IC Role / Device Role / Timing Role: Precision voltage source with known ±5% tolerance and low tempco for traceable DC reference generation. Use Value: Enables field recalibration without reliance on expensive metrology-grade references. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener voltage regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 1N5945B | Through-hole DO-41 package; identical VZ (68V), but RθJA = 500°C/W and PD = 1.5W at +25°C | Not suitable for high-density SMT designs or high-power transient clamping | Select only if legacy through-hole assembly or lower-cost prototyping is required |
| SMBJ68A | TVS diode (not Zener); 68V standoff, 100W peak pulse power, bidirectional, higher leakage (5µA @ VRWM) | Optimized for fast ESD/surge clamping, not precision DC regulation | Choose for transient-only protection where DC regulation accuracy is secondary |
Compared with 1N5945B, the 1SMB5945B-13 delivers 2× power handling and superior thermal performance in SMT layouts; versus SMBJ68A, it offers tighter DC voltage control and lower leakage but no sub-nanosecond transient response.
Availability
1SMB5945B-13 is available at Aetrix Electronics and suitable for industrial power supply regulation, automotive ECU overvoltage clamp, and telecom line card surge protection requiring stable component supply across extended production cycles.
Supply support for 1SMB5945B-13 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
Diodes Incorporated is a global manufacturer of discrete semiconductors and analog ICs, specializing in high-reliability components for power management, signal integrity, and protection applications.
This part belongs to the 1SMB59xxB series of surface-mount Zener diodes designed specifically for automated SMT assembly in industrial, automotive, and telecom power systems requiring robust, RoHS-compliant voltage regulation.
FAQ
What is the maximum continuous reverse voltage this Zener can regulate at ambient temperature?
The 1SMB5945B-13 regulates continuously at its nominal zener voltage of 68V (64.6–71.4V range) with 5.5mA test current. At +25°C ambient, its maximum continuous power dissipation is 550mW before derating begins at 4.4mW/°C above that temperature.
How does its thermal resistance compare to through-hole equivalents?
Its RθJA is 226°C/W on FR-4 PCB per Diodes Inc. AP02001 layout-significantly lower than the 500°C/W typical of through-hole 1N5945B. This allows 2.7× higher continuous power handling in SMT designs with proper copper pour.
Is this device suitable for precision voltage reference applications?
No-it has ±5% VZ tolerance and a temperature coefficient curve peaking near 68V (≈+3.5mV/°C), making it appropriate for general-purpose regulation or overvoltage clamping, not metrology-grade references requiring <0.1% accuracy or low tempco.
Does it require external series resistance in typical applications?
Yes-like all Zener diodes, it must be used with a current-limiting resistor to set operating current within the 5.5mA test point and avoid exceeding 3.0W dissipation. The resistor value is calculated as (VIN − 68V)/IZ, where IZ is chosen between 1mA and 120mA per datasheet limits.
1SMB5945B-13 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Diodes Incorporated
- Series:
- -
- Package/Case:
- DO-214AA, SMB
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Voltage - Zener (Nom) (Vz):
- 68 V
- Tolerance:
- ±5%
- Power - Max:
- 3 W
- Impedance (Max) (Zzt):
- 120 Ohms
- Current - Reverse Leakage @ Vr:
- 1 µA @ 51.7 V
- Voltage - Forward (Vf) (Max) @ If:
- 1.5 V @ 200 mA
- Operating Temperature:
- -65°C ~ 150°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SMB
1SMB5945B-13 FAQ
1.How can I place an order for 1SMB5945B-13 through Aetrix?
Please submit a Request for Quotation (RFQ) for 1SMB5945B-13 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 1SMB5945B-13 reliable?
The price and inventory of 1SMB5945B-13 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1SMB5945B-13 is usually 5 days.
3.What payment methods are accepted for 1SMB5945B-13?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1SMB5945B-13 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1SMB5945B-13?
1SMB5945B-13 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1SMB5945B-13 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 1SMB5945B-13?
For technical support, including 1SMB5945B-13 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1SMB5945B-13 requirements.
6.How does Aetrix verify that 1SMB5945B-13 is sourced from the original manufacturer or authorized distributors?
All 1SMB5945B-13 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 1SMB5945B-13 meets industry standards.
7.What is the process for return or replacement of 1SMB5945B-13?
All 1SMB5945B-13 units undergo pre-shipment inspection (PSI). If there is an issue with 1SMB5945B-13, 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 1SMB5945B-13 part is unused and in its original packaging.
Return procedure for 1SMB5945B-13:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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