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onsemi SZ1SMB5921BT3G
- Part No.:
- SZ1SMB5921BT3G
- Manufacturer:
- onsemi
- Category:
- Single Zener Diodes
- Package:
- DO-214AA, SMB
- Datasheet:
-
SZ1SMB5921BT3G.pdf
- Description:
- DIODE ZENER 6.8V 3W SMB
- Quantity:
- Payment:
- Shipping:
Inventory:6,805
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Product details
Overview
SZ1SMB5921BT3G from onsemi is a 3 W surface-mount Zener diode with nominal zener voltage of 6.8 V, maximum zener impedance of 55.1 Ω at 2.5 mA test current, and reverse leakage current ≤5 μA at 5.2 V, used for precision voltage regulation and overvoltage protection in DC power supplies and automotive control modules.
For engineers reviewing the SZ1SMB5921BT3G datasheet, pinout, applications, or equivalent options, this page delivers verified electrical parameters, thermal derating behavior, AEC−Q101 qualification status, SMB package mechanical data, and real-world design implications for stable voltage reference and transient suppression circuits.
Technical Context
This device operates as a two-terminal voltage reference where reverse-biased junction breakdown provides stable regulation. It features a ±5% tolerance on nominal 6.8 V zener voltage, specified at IZT = 2.5 mA and TL = 30°C, with thermal resistance from junction-to-lead of 40 °C/W enabling high-power dissipation at controlled lead temperature.
The SMB (Case 403A) package supports top-side or bottom-side PCB mounting, includes a cathode polarity band, and meets UL 94 V−0 flammability rating. It is Pb−Free, AEC−Q101 qualified, and rated for −65 °C to +150 °C operating temperature range.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 6.46 V (min) to 7.14 V (max) at IZT = 2.5 mA - defines regulation window under standard test conditions |
| Zener Impedance (ZZT) | 55.1 Ω max at IZT = 2.5 mA - indicates voltage stability under small-signal AC perturbation |
| Max Power Dissipation (PD) | 3.0 W @ TL = 75°C - usable power limit when lead temperature is held at 75°C; derates 25 mW/°C above that |
| Reverse Leakage (IR) | ≤5 μA at VR = 5.2 V - ensures minimal quiescent current in standby regulation circuits |
| Junction-to-Lead Thermal Resistance (RJL) | 40 °C/W - enables direct thermal path to PCB copper for sustained 3 W operation with proper layout |
| ESD Rating | Class 3 (>16 kV) per HBM - supports robust handling in automotive and industrial assembly environments |
| Operating Temperature | −65 °C to +150 °C - validated for under-hood automotive and industrial ambient extremes |
Pinout & Package
SZ1SMB5921BT3G is housed in an SMB (Case 403A) surface-mount plastic package with cathode indicated by a polarity band. The package has a flat handling surface, modified L-bend leads for enhanced pad contact, and void-free transfer-molded construction rated UL 94 V−0.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction terminal / low-side reference node | Connected to circuit ground or lower potential; forms return path during forward bias or zener regulation |
| Cathode | Zener breakdown terminal / regulated output node | Connected to supply rail needing stabilization; maintains ~6.8 V relative to anode when reverse biased above VZ |
Key Features
| Feature | Design Value |
|---|---|
| AEC−Q101 Qualified | Validated for automotive electronics use including engine control units and body modules requiring reliability under thermal cycling and vibration |
| 3 W Steady-State Power | Supports higher-current regulation than standard 1 W Zeners-enables single-device solutions for 100–200 mA load applications |
| Low Zener Impedance (55.1 Ω) | Minimizes output voltage variation under dynamic load changes-critical for noise-sensitive analog references |
| Pb−Free & RoHS Compliant | Meets global environmental compliance requirements without sacrificing solderability or thermal performance |
| ESD Robustness (>16 kV HBM) | Reduces risk of field failure during handling and board assembly in uncontrolled ESD environments |
Applications
| Automotive Engine Control Unit (ECU) Reference | Industrial PLC Analog Input Protection |
|---|---|
Use Scenario: Stabilizing 5 V or 6.8 V reference rail for microcontroller ADC and sensor interface circuits within under-hood ECUs. IC Role / Device Role / Timing Role: Zener voltage regulator providing fixed bias point for precision analog front-ends. Use Value: Maintains <±2% regulation across −40 °C to +125 °C ambient due to AEC−Q101 validation and low tempco below 10 mV/°C for VZ = 6.8 V. |
Use Scenario: Clamping input transients on 0–10 V analog sensor channels in programmable logic controllers exposed to industrial EMI. IC Role / Device Role / Timing Role: Overvoltage protector limiting signal rail excursions to safe levels before downstream op-amps. Use Value: Absorbs up to 3 W surge energy without degradation, leveraging 55.1 Ω ZZT to limit clamping overshoot during fast transients. |
| DC-DC Converter Feedback Divider | LED Driver Current Sense Reference |
Use Scenario: Replacing TL431-based shunt regulators in isolated flyback feedback networks where cost and footprint are constrained. IC Role / Device Role / Timing Role: Passive voltage reference setting output voltage via resistor divider ratio. Use Value: Eliminates need for external biasing circuitry; 6.8 V nominal VZ allows precise 12 V or 24 V output targeting with standard resistor values. |
Use Scenario: Providing stable reference for constant-current LED driver ICs in outdoor lighting systems subject to wide temperature swings. IC Role / Device Role / Timing Role: Precision voltage reference for current-sense amplifier offset calibration. Use Value: Low 5 μA leakage at 5.2 V ensures negligible error contribution to sense resistor voltage drop, preserving ±1% current accuracy. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener voltage regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 1SMB5921BT3G | Same electrical specs and SMB package; lacks SZ prefix and AEC−Q101 qualification | Not validated for automotive use; suitable only for commercial/industrial grade designs | Select when AEC−Q101 compliance is not required and cost sensitivity outweighs qualification needs |
| BZX84-C6V8LT1G | Smaller SOT-23 package, 350 mW rating, 6.8 V ±5%, ZZT = 40 Ω @ 5 mA | Lower power handling limits use to ≤50 mA loads; less thermal margin in dense layouts | Choose for space-constrained consumer applications where 3 W capability is unnecessary |
Compared with 1SMB5921BT3G and BZX84-C6V8LT1G, SZ1SMB5921BT3G uniquely combines automotive qualification, 3 W power capability, and SMB mechanical robustness-making it the only option among the three for under-hood voltage reference or high-energy transient clamping where reliability and thermal endurance are non-negotiable.
Availability
SZ1SMB5921BT3G is available at Aetrix Electronics and suitable for automotive engine control units, industrial PLC analog input stages, and DC-DC converter feedback networks requiring stable component supply with full traceability and long-term lifecycle support.
Supply support for SZ1SMB5921BT3G 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 is a global semiconductor supplier delivering energy-efficient silicon solutions for automotive, industrial, cloud, medical, and IoT applications, with core expertise in power management, analog, sensors, and connectivity.
SZ1SMB5921BT3G belongs to the 1SMB59xxBT3G/SZ1SMB59xxT3G family-engineered specifically for high-reliability voltage regulation and transient suppression in harsh-environment electronics, especially where AEC−Q101 compliance and 3 W steady-state operation are mandatory.
FAQ
What is the nominal zener voltage and tolerance of SZ1SMB5921BT3G?
The nominal zener voltage of SZ1SMB5921BT3G is 6.8 V with a tolerance of ±5%, meaning the actual measured VZ falls between 6.46 V and 7.14 V when tested at IZT = 2.5 mA and TL = 30°C. This tolerance is confirmed in the Electrical Characteristics table on page 3 of the onsemi datasheet, and applies directly to the SZ1SMB5921BT3G part number.
Is SZ1SMB5921BT3G qualified for automotive applications?
Yes, SZ1SMB5921BT3G is explicitly AEC−Q101 qualified and PPAP capable, as stated in the Features section of the onsemi datasheet. The "SZ" prefix denotes automotive-grade manufacturing controls and site-specific change management, distinguishing it from the commercial-grade 1SMB5921BT3G variant. This makes SZ1SMB5921BT3G suitable for deployment in engine control units, body electronics, and ADAS subsystems.
What is the maximum power dissipation and thermal derating behavior of SZ1SMB5921BT3G?
SZ1SMB5921BT3G has a maximum steady-state power dissipation of 3.0 W at lead temperature (TL) = 75°C, with linear derating of 25 mW/°C above that temperature. Its junction-to-lead thermal resistance is 40 °C/W, enabling effective heat transfer to PCB copper. These values are specified in the Maximum Ratings table and Figure 1 (Steady State Power Derating) of the official onsemi datasheet for SZ1SMB5921BT3G.
What package type and dimensions does SZ1SMB5921BT3G use?
SZ1SMB5921BT3G uses the SMB package (Case 403A), a surface-mount plastic case with overall dimensions of 3.56 mm × 4.32 mm × 1.02 mm (L × W × H), cathode polarity band marking, and modified L-bend leads. Mechanical drawings and footprint recommendations are provided in the Package Dimensions section (page 6) of the onsemi datasheet for SZ1SMB5921BT3G.
How does the zener impedance of SZ1SMB5921BT3G affect its regulation performance?
The maximum zener impedance (ZZT) of SZ1SMB5921BT3G is 55.1 Ω at IZT = 2.5 mA, which directly determines how much the output voltage varies under changing load current. Lower ZZT yields tighter regulation-this value enables stable 6.8 V reference performance even with ±10 mA load shifts, making SZ1SMB5921BT3G suitable for precision analog circuits where voltage drift must remain under 50 mV.
SZ1SMB5921BT3G Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- DO-214AA, SMB
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Voltage - Zener (Nom) (Vz):
- 6.8 V
- Tolerance:
- ±5%
- Power - Max:
- 3 W
- Impedance (Max) (Zzt):
- 2.5 Ohms
- Current - Reverse Leakage @ Vr:
- 5 µA @ 5.2 V
- Voltage - Forward (Vf) (Max) @ If:
- 1.5 V @ 200 mA
- Operating Temperature:
- -65°C ~ 150°C
- Grade:
- Automotive
- Qualification:
- AEC-Q101
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SMB
SZ1SMB5921BT3G FAQ
1.How can I place an order for SZ1SMB5921BT3G through Aetrix?
Please submit a Request for Quotation (RFQ) for SZ1SMB5921BT3G 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 SZ1SMB5921BT3G reliable?
The price and inventory of SZ1SMB5921BT3G are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SZ1SMB5921BT3G is usually 5 days.
3.What payment methods are accepted for SZ1SMB5921BT3G?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SZ1SMB5921BT3G transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SZ1SMB5921BT3G?
SZ1SMB5921BT3G orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SZ1SMB5921BT3G 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 SZ1SMB5921BT3G?
For technical support, including SZ1SMB5921BT3G datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SZ1SMB5921BT3G requirements.
6.How does Aetrix verify that SZ1SMB5921BT3G is sourced from the original manufacturer or authorized distributors?
All SZ1SMB5921BT3G 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 SZ1SMB5921BT3G meets industry standards.
7.What is the process for return or replacement of SZ1SMB5921BT3G?
All SZ1SMB5921BT3G units undergo pre-shipment inspection (PSI). If there is an issue with SZ1SMB5921BT3G, 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 SZ1SMB5921BT3G part is unused and in its original packaging.
Return procedure for SZ1SMB5921BT3G:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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