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onsemi 1SMB5942BT3
- Part No.:
- 1SMB5942BT3
- Manufacturer:
- onsemi
- Category:
- Single Zener Diodes
- Package:
- DO-214AA, SMB
- Datasheet:
-
1SMB5942BT3.pdf
- Description:
- DIODE ZENER 51V 3W SMB
- Quantity:
- Payment:
- Shipping:
Inventory:5,617
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Product details
Overview
1SMB5942BT3 from onsemi is a 3 W surface-mount Zener diode with nominal zener voltage of 51 V, maximum zener impedance of 7.3 Ω at 70 mA test current, and reverse leakage current ≤0.25 μA at 38.8 V, designed for precision voltage regulation in DC power supplies and overvoltage protection circuits.
For engineers reviewing the 1SMB5942BT3 datasheet, pinout, applications, or equivalent options, key selection criteria include zener voltage tolerance (±5%), thermal resistance (226 °C/W at TA = 25°C), surge power capability (up to 100 W non-repetitive), and AEC−Q101 qualification status for automotive-grade reliability.
Technical Context
This device operates as a two-terminal voltage reference diode, conducting in reverse breakdown when reverse bias exceeds its specified zener voltage (48.45–53.55 V). It maintains regulation across a wide current range (IZK = 1 mA to IZM = 29 A) with low dynamic impedance and temperature coefficient optimized for stable DC rail clamping.
Its SMB (Case 403A) package supports top- or bottom-side PCB mounting, features a modified L-bend lead for enhanced pad contact, and meets UL 94 V−0 flammability rating. The cathode is marked by a polarity band, and the device is Pb-free with ESD rating >16 kV per HBM.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 48.45–53.55 V @ IZT = 70 mA - defines precise regulation window for 51 V nominal rail stabilization |
| Zener Impedance (ZZT) | 7.3 Ω max @ IZT = 70 mA - ensures minimal output voltage deviation under load transients |
| Max DC Zener Current (IZM) | 29 A - sets absolute upper limit for continuous power dissipation at rated voltage |
| Reverse Leakage (IR) | ≤0.25 μA @ VR = 38.8 V - guarantees negligible standby current in high-impedance sensing paths |
| Power Dissipation (PD) | 3.0 W @ TL = 75°C - requires heatsinking or board copper area for sustained operation above ambient |
| Thermal Resistance (RJA) | 226 °C/W @ TA = 25°C - determines junction temperature rise under given PCB layout and airflow |
| ESD Rating | Class 3 (>16 kV) HBM - enables robust handling in automated SMT assembly without special ESD controls |
Pinout & Package
SMB (Case 403A) surface-mount plastic package with cathode indicated by polarity band; dimensions: 4.32 mm × 2.20 mm × 1.02 mm (L × W × H); flat handling surface for accurate placement; modified L-bend leads for increased solder joint reliability.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction terminal / low-voltage reference node | Connected to circuit ground or lower-potential rail during zener operation; carries full reverse current in regulation mode |
| Cathode | Zener breakdown terminal / regulated output node | Connected to protected voltage rail; maintains stable 51 V output relative to anode when reverse biased above VZ |
Key Features
| Feature | Design Value |
|---|---|
| ±5% zener voltage tolerance | Enables tight regulation without post-production trimming in cost-sensitive power supply designs |
| AEC−Q101 qualified (SZ variant) | Validates reliability for automotive body electronics, infotainment, and ADAS power rails where field failure is unacceptable |
| UL 94 V−0 flammability rating | Meets safety standards for enclosed industrial equipment and consumer devices requiring fire-resistant components |
| Top- or bottom-side mounting capability | Supports flexible PCB layout in space-constrained modules such as LED drivers and sensor signal conditioners |
| Pb-free (RoHS-compliant) construction | Ensures compliance with global environmental regulations and eliminates lead contamination risk in rework processes |
Applications
| DC Power Supply Regulation | Overvoltage Protection Circuit |
|---|---|
|
Use Scenario: Stabilizing 51 V intermediate rail in telecom power modules with ±5% input variation. IC Role / Device Role / Timing Role: Two-terminal shunt regulator maintaining constant output voltage despite load and line fluctuations. Use Value: Delivers 3 W continuous dissipation capability with <7.3 Ω dynamic impedance to suppress ripple and transient spikes within ±0.5 V. |
Use Scenario: Clamping surge-induced voltage spikes on 48 V CAN bus power lines in commercial vehicles. IC Role / Device Role / Timing Role: Fast-acting crowbar element that conducts only when voltage exceeds 53.55 V threshold. Use Value: Limits peak voltage to safe levels using 100 W non-repetitive surge rating and <0.25 μA leakage below clamp point. |
| Industrial Sensor Excitation | LED String Bias Reference |
|
Use Scenario: Providing stable excitation voltage for 4–20 mA loop-powered pressure transmitters operating from unregulated 24–60 V inputs. IC Role / Device Role / Timing Role: Precision voltage reference source referenced to system ground, enabling ratiometric ADC measurements. Use Value: Maintains <±0.5% drift over −65°C to +150°C due to low temperature coefficient and tight 5% initial tolerance. |
Use Scenario: Biasing constant-current driver ICs for high-brightness LED arrays in architectural lighting fixtures. IC Role / Device Role / Timing Role: Shunt regulator establishing fixed headroom voltage for linear LED current controllers. Use Value: Enables thermal stability via 226 °C/W RJA and supports pulsed operation up to 100 W with 10 ms pulse width. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener voltage regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 1N5942BRLG | Same 51 V nominal zener voltage but DO-41 through-hole package; higher RJA (500 °C/W); no AEC−Q101 qualification | Preferred for prototyping or low-volume through-hole assemblies; unsuitable for automotive or high-density SMT layouts | Select when manual soldering or legacy board compatibility is required; avoid for production SMT or automotive use |
| SZ1SMB5942BT3G | Identical electrical specs and SMB package; includes AEC−Q101 qualification and PPAP documentation support | Required for automotive OEM programs; supports traceable sourcing and extended temperature validation | Choose for automotive, industrial, or safety-critical applications where process control and qualification evidence are mandatory |
Compared with 1SMB5942BT3, 1N5942BRLG offers mechanical compatibility with legacy through-hole designs but lacks surface-mount efficiency and automotive qualification, while SZ1SMB5942BT3G adds formal AEC−Q101 validation and PPAP readiness-critical for Tier 1 automotive supply chains without altering electrical performance.
Availability
1SMB5942BT3 is available at Aetrix Electronics and suitable for DC power supply regulation, overvoltage protection circuits, industrial sensor excitation, and LED string bias reference applications requiring stable component supply and RoHS-compliant packaging.
Supply support for 1SMB5942BT3 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, analog, sensor, and connectivity solutions for automotive, industrial, cloud, and consumer markets.
The 1SMB59xxBT3 series delivers high-power, precision Zener regulation in compact SMB packages, targeting cost-sensitive yet reliability-demanding applications including automotive subsystems, industrial automation, and telecom infrastructure.
FAQ
What is the zener voltage tolerance for 1SMB5942BT3?
The 1SMB5942BT3 has a zener voltage tolerance of ±5%, meaning its actual breakdown voltage falls between 48.45 V and 53.55 V when tested at 70 mA. This tolerance is confirmed in the Electrical Characteristics table on page 3 of the official onsemi datasheet. The 1SMB5942BT3 achieves this specification without requiring external trimming, making it suitable for production-level voltage reference designs where consistency matters.
Is 1SMB5942BT3 suitable for automotive applications?
The standard 1SMB5942BT3 is not AEC−Q101 qualified; however, its automotive-grade counterpart SZ1SMB5942BT3G is fully qualified and PPAP-capable. While the 1SMB5942BT3 shares identical electrical parameters and SMB packaging, only the SZ-prefix version undergoes the extended stress testing required for automotive use. Therefore, 1SMB5942BT3 should be used in industrial or commercial systems, whereas SZ1SMB5942BT3G is required for automotive ECUs or body control modules.
What is the maximum surge power rating for 1SMB5942BT3?
The 1SMB5942BT3 supports up to 100 W of non-repetitive peak surge power for pulse widths ≤10 ms, as shown in Figure 2 of the onsemi datasheet. This capability allows the 1SMB5942BT3 to absorb transient overvoltages-such as ESD events or inductive switching spikes-without degradation. Its 3 W steady-state rating remains unchanged, so repeated surges must be spaced to allow thermal recovery before the next event.
How does the thermal resistance of 1SMB5942BT3 affect PCB layout?
The 1SMB5942BT3 has a junction-to-ambient thermal resistance (RJA) of 226 °C/W at TA = 25°C on FR-4 board with recommended footprint. To maintain safe junction temperatures below 150°C, PCB layout must include adequate copper area-typically ≥100 mm² of 1 oz copper connected to both terminals-or forced airflow. Without thermal relief, even 1 W dissipation raises junction temperature by over 225°C above ambient, risking premature failure.
Does 1SMB5942BT3 have Pb-free construction?
Yes, the "G" suffix in 1SMB5942BT3 indicates Pb-free (RoHS-compliant) packaging, confirmed in the Ordering Information section of the datasheet. The device uses matte tin plating on leads and halogen-free molding compound. This makes 1SMB5942BT3 compatible with lead-free reflow profiles (peak temperature up to 260°C for 10 seconds), and eliminates regulatory barriers for export to EU, China, and other RoHS-regulated markets.
1SMB5942BT3 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- DO-214AA, SMB
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Voltage - Zener (Nom) (Vz):
- 51 V
- Tolerance:
- ±5%
- Power - Max:
- 3 W
- Impedance (Max) (Zzt):
- 70 Ohms
- Current - Reverse Leakage @ Vr:
- 1 µA @ 38.8 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
1SMB5942BT3 FAQ
1.How can I place an order for 1SMB5942BT3 through Aetrix?
Please submit a Request for Quotation (RFQ) for 1SMB5942BT3 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 1SMB5942BT3 reliable?
The price and inventory of 1SMB5942BT3 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1SMB5942BT3 is usually 5 days.
3.What payment methods are accepted for 1SMB5942BT3?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1SMB5942BT3 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1SMB5942BT3?
1SMB5942BT3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1SMB5942BT3 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 1SMB5942BT3?
For technical support, including 1SMB5942BT3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1SMB5942BT3 requirements.
6.How does Aetrix verify that 1SMB5942BT3 is sourced from the original manufacturer or authorized distributors?
All 1SMB5942BT3 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 1SMB5942BT3 meets industry standards.
7.What is the process for return or replacement of 1SMB5942BT3?
All 1SMB5942BT3 units undergo pre-shipment inspection (PSI). If there is an issue with 1SMB5942BT3, 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 1SMB5942BT3 part is unused and in its original packaging.
Return procedure for 1SMB5942BT3:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
1SMB5942BT3 Tags
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