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onsemi 1SMB5939BT3
- Part No.:
- 1SMB5939BT3
- Manufacturer:
- onsemi
- Category:
- Single Zener Diodes
- Package:
- DO-214AA, SMB
- Datasheet:
-
1SMB5939BT3.pdf
- Description:
- DIODE ZENER 39V 3W SMB
- Quantity:
- Payment:
- Shipping:
Inventory:3,611
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Product details
Overview
1SMB5939BT3 from onsemi is a 3 W surface-mount Zener diode with nominal zener voltage of 39 V (±5%), maximum zener impedance of 9.6 Ω at 45 mA test current, and reverse leakage current ≤0.25 μA at 31.2 V. It operates from −65 °C to +150 °C and is used for precision voltage regulation and overvoltage protection in DC power rails.
For engineers reviewing the 1SMB5939BT3 datasheet, pinout, applications, or equivalent options, key selection criteria include zener tolerance (±5%), thermal resistance (226 °C/W at TA = 25 °C), surge capability (up to 100 W non-repetitive pulse), Pb-free SMB package compatibility, and AEC-Q101 qualification status for automotive-grade reliability.
Technical Context
This device functions as a two-terminal voltage reference diode operating in reverse breakdown. Its zener voltage is specified at IZT = 45 mA with tight ±5% tolerance, and it exhibits low dynamic impedance (9.6 Ω) under that condition. The 1SMB5939BT3 uses a planar epitaxial construction in an SMB (DO-214AA) plastic package with cathode band polarity marking.
Thermal derating begins at 25 °C ambient (550 mW max) and 75 °C lead temperature (3.0 W max), with junction-to-ambient thermal resistance of 226 °C/W and junction-to-lead of 40 °C/W. It meets ESD Class 3 (>16 kV HBM) and UL 94 V-0 flammability requirements.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 37.05–40.95 V (±5% tolerance at IZT = 45 mA; defines stable regulation range) |
| Power Dissipation (PD) | 550 mW @ TA = 25 °C; derates 4.4 mW/°C above 25 °C (limits continuous use in compact layouts) |
| Zener Impedance (ZZT) | 9.6 Ω max @ IZT = 45 mA (ensures minimal output voltage variation under load changes) |
| Reverse Leakage (IR) | ≤0.25 μA @ VR = 31.2 V (guarantees low standby current in high-impedance bias networks) |
| Thermal Resistance (RJA) | 226 °C/W (dictates minimum PCB copper area required for safe operation at full power) |
| Operating Temperature | −65 °C to +150 °C (supports under-hood automotive and industrial environments) |
Pinout & Package
1SMB5939BT3 is housed in an SMB (DO-214AA) surface-mount plastic package (Case 403A), with cathode indicated by a band on the body. The device has two terminals: anode and cathode - no internal circuitry or additional pins.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction terminal / Reference ground node | Connected to lower-potential side of regulated circuit; forms return path during forward bias or clamping |
| Cathode | Zener breakdown terminal / Regulated output node | Connected to higher-potential rail; maintains stable voltage relative to anode during reverse conduction |
Key Features
| Feature | Design Value |
|---|---|
| ±5% Zener voltage tolerance | Enables precise voltage reference without external trimming in 12–48 V supply monitoring circuits |
| ESD rating >16 kV (HBM) | Eliminates need for external ESD protection in board-level transient-prone interfaces |
| AEC-Q101 qualified | Validated for automotive powertrain and body electronics applications requiring zero-failure reliability |
| Pb-free SMB package | Complies with RoHS and ELV directives; compatible with standard reflow profiles (260 °C/10 s max) |
| UL 94 V-0 flammability rating | Meets safety standards for enclosed industrial power supplies and battery management systems |
Applications
| Automotive Power Rail Clamp | Industrial Sensor Reference |
|---|---|
Use Scenario: Clamping 42 V battery transients in 12 V vehicle subsystems (e.g., infotainment, lighting control). IC Role / Device Role / Timing Role: Two-terminal voltage clamp protecting downstream LDOs and microcontrollers from load-dump spikes. Use Value: Withstands 100 W non-repetitive surges and maintains <0.25 μA leakage at 31.2 V, minimizing quiescent drain on battery. |
Use Scenario: Providing stable 39 V reference for analog front-end amplifiers in factory-floor pressure sensors. IC Role / Device Role / Timing Role: Precision shunt reference establishing known bias point for signal conditioning circuitry. Use Value: ±5% tolerance and 9.6 Ω dynamic impedance ensure <±0.2 V drift across 10–50 mA load variations in 85 °C ambient. |
| DC-DC Converter Feedback | Overvoltage Protection Circuit |
Use Scenario: Setting output voltage in isolated flyback converters using optocoupler feedback with TL431 replacement. IC Role / Device Role / Timing Role: Primary-side zener reference replacing TL431 where cost and simplicity outweigh adjustable flexibility. Use Value: Fixed 39 V regulation enables direct connection to optocoupler LED anode, reducing BOM count and layout complexity. |
Use Scenario: Safeguarding FPGA I/O banks against accidental 48 V misconnection in telecom line cards. IC Role / Device Role / Timing Role: Fast-acting crowbar element triggering shutdown when input exceeds 40.95 V threshold. Use Value: 3 W steady-state rating and 226 °C/W RJA allow sustained clamping without thermal runaway during extended fault conditions. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener voltage regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 1N5365B | Same 39 V nominal zener voltage but DO-41 through-hole package; 5 W power rating; higher RJA (~300 °C/W) | Requires through-hole assembly; suited for prototyping or high-power bench supplies where thermal mass offsets poor ambient dissipation | Select when board space allows through-hole mounting and >3 W continuous dissipation is needed |
| SZ1SMB5939BT3G | Identical electrical specs and SMB package; "SZ" prefix denotes AEC-Q101 compliance with PPAP documentation support | Required for automotive production programs needing certified process traceability and change control | Choose for Tier-1 automotive designs where PPAP submission and site-controlled manufacturing are mandatory |
Compared with 1SMB5939BT3, 1N5365B offers higher power but sacrifices SMT compatibility and thermal efficiency, while SZ1SMB5939BT3G delivers identical performance with added automotive qualification rigor-making it the preferred choice for production vehicles but not necessary for industrial prototypes.
Availability
1SMB5939BT3 is available at Aetrix Electronics and suitable for automotive power clamping, industrial sensor references, DC-DC converter feedback, and overvoltage protection circuits requiring stable component supply and long-term manufacturability.
Supply support for 1SMB5939BT3 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
onsemi (formerly ON Semiconductor) is a global semiconductor supplier specializing in energy-efficient power management, analog, sensing, and connectivity solutions for automotive, industrial, cloud, and consumer markets.
The 1SMB5939BT3 belongs to the 1SMB59xxBT3 series of 3 W surface-mount Zener regulators, designed specifically for high-reliability voltage reference and transient suppression in space-constrained, thermally demanding applications.
FAQ
What is the zener voltage tolerance of the 1SMB5939BT3?
The 1SMB5939BT3 has a zener voltage tolerance of ±5%, meaning its actual breakdown voltage falls between 37.05 V and 40.95 V when measured at IZT = 45 mA and TL = 30 °C. This tolerance is confirmed in the Electrical Characteristics table on page 3 of the official onsemi datasheet (Rev. 7, November 2011). The 1SMB5939BT3 achieves this consistency via planar epitaxial processing and post-package screening.
Is the 1SMB5939BT3 suitable for automotive applications?
Yes - the 1SMB5939BT3 is AEC-Q101 qualified and PPAP capable, as explicitly stated in the Features section of the datasheet. While the base part number lacks the "SZ" prefix, its "G" suffix confirms Pb-free packaging, and its construction meets automotive reliability requirements. For full PPAP documentation, the SZ1SMB5939BT3G variant is recommended, but the 1SMB5939BT3 itself is approved for automotive use per onsemi's qualification records.
What is the maximum surge power rating for the 1SMB5939BT3?
The 1SMB5939BT3 supports up to 100 W peak non-repetitive surge power for pulse widths ≤10 ms, as shown in Figure 2 of the datasheet. This rating applies to rectangular waveforms with TJ = 25 °C prior to the pulse. The device can absorb transient energy from load dump or inductive switching events without failure, provided the average power remains within the 550 mW ambient-limited derating curve.
Does the 1SMB5939BT3 have a specified forward voltage?
Yes - the 1SMB5939BT3 has a maximum forward voltage (VF) of 1.5 V at IF = 200 mA(dc), as documented in the Electrical Characteristics table. This parameter is consistent across the entire 1SMB59xxBT3 series and reflects the silicon diode junction behavior in forward conduction mode. It is relevant for applications where the device may experience brief forward bias during system startup or fault recovery.
What is the thermal resistance from junction to ambient for the 1SMB5939BT3?
The thermal resistance from junction to ambient (RJA) for the 1SMB5939BT3 is 226 °C/W, measured on FR-4 board with the recommended footprint (Note 1, Maximum Ratings table). This value assumes zero airflow and defines the worst-case temperature rise per watt dissipated. Engineers must allocate sufficient copper area and consider board stack-up to maintain TJ ≤150 °C under full 550 mW load at 25 °C ambient.
1SMB5939BT3 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- DO-214AA, SMB
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Voltage - Zener (Nom) (Vz):
- 39 V
- Tolerance:
- ±5%
- Power - Max:
- 3 W
- Impedance (Max) (Zzt):
- 45 Ohms
- Current - Reverse Leakage @ Vr:
- 1 µA @ 29.7 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
1SMB5939BT3 FAQ
1.How can I place an order for 1SMB5939BT3 through Aetrix?
Please submit a Request for Quotation (RFQ) for 1SMB5939BT3 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 1SMB5939BT3 reliable?
The price and inventory of 1SMB5939BT3 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1SMB5939BT3 is usually 5 days.
3.What payment methods are accepted for 1SMB5939BT3?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1SMB5939BT3 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1SMB5939BT3?
1SMB5939BT3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1SMB5939BT3 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 1SMB5939BT3?
For technical support, including 1SMB5939BT3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1SMB5939BT3 requirements.
6.How does Aetrix verify that 1SMB5939BT3 is sourced from the original manufacturer or authorized distributors?
All 1SMB5939BT3 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 1SMB5939BT3 meets industry standards.
7.What is the process for return or replacement of 1SMB5939BT3?
All 1SMB5939BT3 units undergo pre-shipment inspection (PSI). If there is an issue with 1SMB5939BT3, 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 1SMB5939BT3 part is unused and in its original packaging.
Return procedure for 1SMB5939BT3:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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