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onsemi SZ1SMB5943BT3G
- Part No.:
- SZ1SMB5943BT3G
- Manufacturer:
- onsemi
- Category:
- Single Zener Diodes
- Package:
- DO-214AA, SMB
- Datasheet:
-
SZ1SMB5943BT3G.pdf
- Description:
- DIODE ZENER 56V 3W SMB
- Quantity:
- Payment:
- Shipping:
Inventory:3,444
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Product details
Overview
SZ1SMB5943BT3G from onsemi is a 3 W surface-mount Zener diode with nominal zener voltage of 56 V, ±5% tolerance, 6.7 Ω dynamic impedance at 86 mA test current, and 0.25 μA reverse leakage at 42.6 V. It operates from −65 °C to +150 °C and is AEC−Q101 qualified for automotive power rail regulation and overvoltage clamping.
For engineers reviewing the SZ1SMB5943BT3G datasheet, pinout, applications, or equivalent options, key selection criteria include zener voltage stability under thermal drift, surge power handling up to 1300 W (10/1000 µs), low leakage at rated VR, Pb−free SMB package compatibility with automated SMT assembly, and AEC−Q101 qualification status for automotive use.
Technical Context
This device functions as a precision DC voltage reference and transient voltage suppressor in regulated power supplies and ESD-protected interfaces. Its 56 V nominal breakdown is achieved via heavily doped planar junction construction, with thermal coefficient optimized for stable operation across −65 °C to +150 °C ambient range.
The SMB package provides 226 °C/W junction-to-ambient thermal resistance at 25 °C, derating linearly above that temperature, and supports 3.0 W steady-state dissipation at 75 °C lead temperature. The cathode polarity band enables unambiguous orientation during placement on FR−4 PCBs with recommended footprint per case 403A.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 56 V nominal (min 53.2 V, max 58.8 V) - defines precise clamping threshold for 48 V system protection |
| Zener Test Current (IZT) | 86 mA - operating point where VZ and ZZT are specified; sets minimum bias for stable regulation |
| Zener Impedance (ZZT) | 6.7 Ω @ IZT - low dynamic resistance ensures minimal voltage shift under load transients |
| Reverse Leakage (IR) | 0.25 μA @ 42.6 V - ultra-low leakage preserves efficiency in high-impedance bias networks |
| Power Dissipation (PD) | 3.0 W @ TL = 75 °C - requires thermal relief on copper pour for sustained operation |
| ESD Rating | Class 3 (>16 kV HBM) - withstands direct human-body discharge without degradation |
| AEC−Q101 Qualified | Yes - validated for automotive underhood and infotainment applications per stress test requirements |
Pinout & Package
Package: SMB (Case 403A), surface-mount plastic package with modified L-bend leads, cathode indicated by polarity band, UL 94 V−0 flammability rating, and Pb−free construction.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction terminal / Reference ground node | Connected to circuit common or lower-potential rail; establishes reference for reverse-biased operation |
| Cathode | Zener breakdown terminal / Regulated output node | Connected to protected node; maintains 56 V clamp during overvoltage events |
Key Features
| Feature | Design Value |
|---|---|
| 3 W Power Rating | Enables robust clamping in 12–48 V automotive subsystems without external heatsinking |
| ±5% Zener Tolerance | Reduces binning requirements and simplifies BOM management across production lots |
| Flat Handling Surface | Ensures coplanarity and accurate pick-and-place registration in high-speed SMT lines |
| Top/Bottom Mount Flexibility | Supports dual-side PCB assembly and space-constrained layouts in compact modules |
| Pb−Free Construction | Complies with RoHS Directive 2011/65/EU and JEDEC J-STD-020 reflow profiles |
Applications
| Automotive Body Control Module | Industrial PLC Input Protection |
|---|---|
Use Scenario: Clamping 48 V battery rail surges during load dump in BCM power distribution. IC Role / Device Role / Timing Role: Primary overvoltage protection element placed directly at power entry point before DC/DC converters. Use Value: Withstands 1300 W nonrepetitive surge (10/1000 µs) and maintains <0.25 μA leakage at 42.6 V, minimizing standby current drain. |
Use Scenario: Protecting 24 V digital input channels from field-wiring induced transients in factory automation cabinets. IC Role / Device Role / Timing Role: Standoff diode in parallel with optocoupler input, shunting fast-rising spikes before signal conditioning stage. Use Value: 6.7 Ω ZZT ensures clamped voltage stays within 56 V ±0.5 V during 100 mA transient, preserving input logic thresholds. |
| Telecom PoE Midspan Injector | Medical Diagnostic Power Supply |
Use Scenario: Secondary-side voltage regulation and fault clamping in IEEE 802.3at PoE midspan 57 V output stage. IC Role / Device Role / Timing Role: Precision reference for feedback loop and crowbar element during short-circuit recovery. Use Value: 56 V nominal VZ aligns with PoE+ open-circuit voltage; ±5% tolerance avoids false triggering of OVP circuits. |
Use Scenario: Isolated auxiliary supply monitoring in Class II medical imaging equipment requiring low-leakage references. IC Role / Device Role / Timing Role: Voltage supervisor reference in isolated 56 V bias rail for gate drivers and analog front-end ICs. Use Value: 0.25 μA leakage at 42.6 V prevents measurable error in high-impedance voltage divider networks used for safety-critical monitoring. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener voltage regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 1SMB5943BT3G | No AEC−Q101 qualification; identical electrical specs and SMB package | Not approved for automotive production; suitable for industrial/commercial designs without automotive compliance needs | Select when AEC−Q101 is not required and cost sensitivity favors standard-grade variant |
| MMSZ5262B−TP | 500 mW rating, SOD−123 package, 56 V nominal, ±5%, ZZT = 17 Ω @ 10 mA | Limited to low-power signal-level clamping; insufficient for 3 W surge handling or power rail stabilization | Use only in space-constrained, low-energy circuits where 3 W capability is unnecessary |
Compared with 1SMB5943BT3G, SZ1SMB5943BT3G adds AEC−Q101 validation for automotive deployment, while MMSZ5262B−TP trades power capability for smaller footprint-making SZ1SMB5943BT3G the sole choice for ruggedized 48–60 V rail protection requiring both surge resilience and automotive qualification.
Availability
SZ1SMB5943BT3G is available at Aetrix Electronics and suitable for automotive body control modules, industrial PLC input stages, telecom PoE injectors, and medical diagnostic power supplies requiring stable component supply with full traceability and long-term lifecycle support.
Supply support for SZ1SMB5943BT3G 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 (Semiconductor Components Industries, LLC) is a global semiconductor supplier delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.
SZ1SMB5943BT3G belongs to the 1SMB59xxBT3G/SZ1SMB59xxT3G family of 3 W Zener regulators designed specifically for high-reliability automotive and industrial voltage reference and transient suppression tasks.
FAQ
What is the maximum steady-state power dissipation of SZ1SMB5943BT3G at 75°C lead temperature?
SZ1SMB5943BT3G has a maximum steady-state power dissipation of 3.0 W at 75°C lead temperature, with a derating factor of 25 mW/°C above that temperature. This specification assumes zero lead length and measurement on an FR−4 board using the recommended footprint per case 403A. Exceeding this limit risks thermal runaway and permanent degradation of the zener junction.
Is SZ1SMB5943BT3G suitable for automotive applications?
Yes, SZ1SMB5943BT3G is AEC−Q101 qualified and PPAP capable, making it suitable for automotive applications including body control modules, infotainment power rails, and ADAS sensor supply protection. The "SZ" prefix explicitly denotes automotive-grade screening, unique site controls, and extended reliability testing beyond standard commercial parts like 1SMB5943BT3G.
What is the reverse leakage current specification for SZ1SMB5943BT3G?
SZ1SMB5943BT3G specifies a maximum reverse leakage current (IR) of 0.25 μA at 42.6 V (80% of nominal VZ). This ultra-low leakage is critical for high-impedance bias networks and battery-powered systems where standby current must be minimized. Leakage remains below 1 μA up to 45.15 V per datasheet Figure 6.
Does SZ1SMB5943BT3G have ESD protection built-in?
Yes, SZ1SMB5943BT3G features an ESD rating of Class 3 (>16 kV) per Human Body Model (HBM), verified per AEC−Q101 test conditions. This intrinsic robustness eliminates the need for external ESD diodes in many interface protection schemes and ensures survivability during handling and board assembly.
What is the Zener impedance of SZ1SMB5943BT3G and why does it matter?
SZ1SMB5943BT3G has a maximum Zener impedance (ZZT) of 6.7 Ω at 86 mA test current. Low ZZT ensures minimal deviation in clamped voltage during rapid load or surge current changes-critical for maintaining tight regulation in power supply feedback loops and protecting downstream ICs from overvoltage excursions.
SZ1SMB5943BT3G Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- DO-214AA, SMB
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Voltage - Zener (Nom) (Vz):
- 56 V
- Tolerance:
- ±5%
- Power - Max:
- 3 W
- Impedance (Max) (Zzt):
- 86 Ohms
- Current - Reverse Leakage @ Vr:
- 1 µA @ 42.6 V
- Voltage - Forward (Vf) (Max) @ If:
- 900 mV @ 10 mA
- Operating Temperature:
- -65°C ~ 150°C
- Grade:
- Automotive
- Qualification:
- AEC-Q101
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SMB
SZ1SMB5943BT3G FAQ
1.How can I place an order for SZ1SMB5943BT3G through Aetrix?
Please submit a Request for Quotation (RFQ) for SZ1SMB5943BT3G 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 SZ1SMB5943BT3G reliable?
The price and inventory of SZ1SMB5943BT3G are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SZ1SMB5943BT3G is usually 5 days.
3.What payment methods are accepted for SZ1SMB5943BT3G?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SZ1SMB5943BT3G transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SZ1SMB5943BT3G?
SZ1SMB5943BT3G orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SZ1SMB5943BT3G 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 SZ1SMB5943BT3G?
For technical support, including SZ1SMB5943BT3G datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SZ1SMB5943BT3G requirements.
6.How does Aetrix verify that SZ1SMB5943BT3G is sourced from the original manufacturer or authorized distributors?
All SZ1SMB5943BT3G 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 SZ1SMB5943BT3G meets industry standards.
7.What is the process for return or replacement of SZ1SMB5943BT3G?
All SZ1SMB5943BT3G units undergo pre-shipment inspection (PSI). If there is an issue with SZ1SMB5943BT3G, 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 SZ1SMB5943BT3G part is unused and in its original packaging.
Return procedure for SZ1SMB5943BT3G:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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