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onsemi SZMMSZ5251ET1G
- Part No.:
- SZMMSZ5251ET1G
- Manufacturer:
- onsemi
- Category:
- Single Zener Diodes
- Package:
- SOD-123
- Datasheet:
-
SZMMSZ5251ET1G.pdf
- Description:
- DIODE ZENER 22V 500MW SOD123
- Quantity:
- Payment:
- Shipping:
Inventory:2,896
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Product details
Overview
SZMMSZ5251ET1G from onsemi is a 21 V ±5% Zener voltage regulator diode in SOD-123 package, rated for 500 mW power dissipation at 75 °C on FR-5 board, with 5.6 mA test current (IZT), 29 Ω dynamic impedance (ZZT), and 0.1 µA reverse leakage at 17 V (VR). It serves as a precision voltage reference or overvoltage clamp in low-power analog and power management circuits.
For engineers reviewing the SZMMSZ5251ET1G datasheet, pinout, applications, or equivalent options, key selection criteria include Zener tolerance (±5%), thermal resistance (RJA = 340 °C/W), AEC-Q101 qualification, ESD rating (>16 kV HBM), and SOD-123 footprint compatibility for high-density PCB layouts.
Technical Context
This device operates in reverse-biased Zener breakdown mode to maintain stable voltage regulation across varying load currents. Its 21 V nominal Zener voltage is specified at IZT = 5.6 mA with ±5% tolerance, and it exhibits low dynamic impedance (29 Ω) ensuring minimal voltage deviation under transient current changes.
Designed for automotive and industrial applications, SZMMSZ5251ET1G features AEC-Q101 qualification, Pb-free construction, and Class 3 ESD robustness (>16 kV HBM). Thermal performance is defined by junction-to-ambient resistance of 340 °C/W and maximum junction temperature of +150 °C.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 19.95–22.05 V @ IZT = 5.6 mA; ensures stable reference within ±5% tolerance for precision biasing |
| Power Dissipation (PD) | 500 mW @ TL = 75 °C on FR-5 board; defines continuous operating limit before thermal derating |
| Zener Impedance (ZZT) | 29 Ω @ IZT = 5.6 mA; determines output voltage stability under dynamic load variations |
| Reverse Leakage (IR) | 0.1 µA @ VR = 17 V; guarantees minimal quiescent current in standby or sensing circuits |
| Thermal Resistance (RJA) | 340 °C/W; indicates heat transfer efficiency from junction to ambient air without heatsink |
| ESD Rating | Class 3 (>16 kV) per HBM; enables robust handling in automated assembly and field operation |
| Junction Temp Range | −55 °C to +150 °C; supports deployment in under-hood automotive and industrial environments |
Pinout & Package
SZMMSZ5251ET1G uses the SOD-123 surface-mount plastic package (1.60 × 2.69 × 1.16 mm), with cathode identified by a polarity band. The case is void-free, thermosetting, UL 94 V-0 rated, and solderable at 260 °C for 10 seconds.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (Banded End) | Cathode | Connected to regulated voltage node; reverse-biased terminal during Zener operation |
| 2 (Non-banded End) | Anode | Connected to circuit ground or lower potential; completes Zener conduction path |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 Qualified | Validated for automotive-grade reliability including temperature cycling, humidity, and mechanical stress |
| Pb-Free Construction | Complies with RoHS Directive 2011/65/EU and JEDEC J-STD-020 reflow profile requirements |
| High ESD Robustness | Withstands >16 kV human body model discharge without parameter shift or failure |
| Optimized for Automated Assembly | SOD-123 footprint meets IPC-7351B density guidelines for pick-and-place accuracy and solder joint integrity |
| Stable Temperature Coefficient | TCZ ≈ +0.075 %/°C near 21 V (inferred from Figure 1 trend), minimizing drift over −55 °C to +150 °C |
Applications
| Automotive Sensor Biasing | Industrial Power Supply Clamp |
|---|---|
Use Scenario: Providing stable 21 V reference for analog front-end amplifiers in engine control unit (ECU) temperature sensors. IC Role / Device Role / Timing Role: Zener voltage reference diode establishing fixed bias point for signal conditioning circuitry. Use Value: Maintains sensor accuracy across −40 °C to +125 °C ambient with <±0.5% voltage drift due to tight Zener tolerance and low TCZ. | Use Scenario: Clamping transient overvoltage spikes on 24 V DC input rails in programmable logic controller (PLC) power modules. IC Role / Device Role / Timing Role: Overvoltage protection device shunting surge energy above 22.05 V to ground. Use Value: Absorbs up to 225 W nonrepetitive surge (8 × 20 µs) without degradation, protecting downstream regulators and microcontrollers. |
| Medical Instrument Reference | Consumer Audio DC-DC Feedback |
Use Scenario: Generating precise 21 V reference for ADC reference buffers in portable blood glucose meters. IC Role / Device Role / Timing Role: Precision voltage reference element stabilizing analog measurement chain. Use Value: Delivers <10 ppm/°C effective TC via ±5% VZ tolerance and low ZZT (29 Ω), enabling <0.1% full-scale error over operating range. | Use Scenario: Setting feedback threshold in isolated flyback converter for USB-C PD adapter auxiliary supplies. IC Role / Device Role / Timing Role: Secondary-side Zener clamp defining output voltage setpoint in optocoupler feedback loop. Use Value: Enables compact design using SOD-123 footprint while maintaining 1% output regulation accuracy under line/load transients. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener voltage regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MMSZ5251ET1G | No SZ prefix; not AEC-Q101 qualified; identical electrical specs and SOD-123 package | Suitable for commercial-grade designs where automotive qualification is unnecessary | Select when cost sensitivity outweighs automotive reliability requirements |
| BZX84-C21LT1G | 21 V ±5%, 350 mW rating, SOT-23 package; higher RJA (~450 °C/W); no AEC-Q101 certification | Used in space-constrained consumer electronics where thermal margin is less critical | Choose only if SOT-23 footprint is mandatory and 500 mW derating is acceptable |
Compared with MMSZ5251ET1G and BZX84-C21LT1G, SZMMSZ5251ET1G provides automotive-grade reliability and higher power capability in the same SOD-123 footprint-enabling drop-in replacement in AEC-Q101-compliant systems without layout change, while offering superior thermal performance for sustained 21 V regulation.
Availability
SZMMSZ5251ET1G is available at Aetrix Electronics and suitable for automotive sensor biasing, industrial power supply clamping, and medical instrument reference applications requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for SZMMSZ5251ET1G 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.
SZMMSZ5251ET1G belongs to the SZMMSZ52xxET1G series of AEC-Q101-qualified Zener regulators designed specifically for automotive and high-reliability industrial voltage reference and overvoltage protection functions.
FAQ
What is the Zener voltage tolerance for SZMMSZ5251ET1G?
SZMMSZ5251ET1G has a nominal Zener voltage of 21 V with a standard tolerance of ±5%, resulting in a guaranteed range of 19.95 V to 22.05 V at IZT = 5.6 mA and TL = 30 °C ±1 °C. This tolerance is confirmed in the Electrical Characteristics table on page 2 of the official onsemi datasheet Rev. 10 (October 2025).
Is SZMMSZ5251ET1G suitable for automotive applications?
Yes, SZMMSZ5251ET1G is AEC-Q101 qualified and PPAP capable, with the "SZ" prefix indicating compliance for automotive and other applications requiring unique site and control change requirements. Its −55 °C to +150 °C junction temperature range and Class 3 ESD rating further support under-hood deployment.
What is the maximum power dissipation for SZMMSZ5251ET1G on a standard PCB?
SZMMSZ5251ET1G is rated for 500 mW total power dissipation on FR-5 board at TL = 75 °C, with linear derating of 6.7 mW/°C above that temperature. Peak nonrepetitive surge power reaches 225 W for 8 × 20 µs pulses, as specified in the Maximum Ratings table.
Does SZMMSZ5251ET1G have Pb-free packaging?
Yes, SZMMSZ5251ET1G is supplied in Pb-free packaging, indicated by the "G" suffix and documented in the Ordering Information section. It complies with RoHS Directive 2011/65/EU and is compatible with standard lead-free reflow profiles per JEDEC J-STD-020.
How is the cathode identified on SZMMSZ5251ET1G?
The cathode of SZMMSZ5251ET1G is marked by a polarity band on the SOD-123 package body, corresponding to Pin 1 in the mechanical outline. This marking aligns with the standard SOD-123 pinout shown in the CASE 425 STYLE 1 diagram on page 6 of the datasheet.
SZMMSZ5251ET1G Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- SZMMSZ52xxxT1G
- Package/Case:
- SOD-123
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Voltage - Zener (Nom) (Vz):
- 22 V
- Tolerance:
- ±5%
- Power - Max:
- 500 mW
- Impedance (Max) (Zzt):
- 29 Ohms
- Current - Reverse Leakage @ Vr:
- 100 nA @ 17 V
- Voltage - Forward (Vf) (Max) @ If:
- 900 mV @ 10 mA
- Operating Temperature:
- -55°C ~ 150°C
- Grade:
- Automotive
- Qualification:
- AEC-Q101
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOD-123
SZMMSZ5251ET1G FAQ
1.How can I place an order for SZMMSZ5251ET1G through Aetrix?
Please submit a Request for Quotation (RFQ) for SZMMSZ5251ET1G 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 SZMMSZ5251ET1G reliable?
The price and inventory of SZMMSZ5251ET1G are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SZMMSZ5251ET1G is usually 5 days.
3.What payment methods are accepted for SZMMSZ5251ET1G?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SZMMSZ5251ET1G transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SZMMSZ5251ET1G?
SZMMSZ5251ET1G orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SZMMSZ5251ET1G 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 SZMMSZ5251ET1G?
For technical support, including SZMMSZ5251ET1G datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SZMMSZ5251ET1G requirements.
6.How does Aetrix verify that SZMMSZ5251ET1G is sourced from the original manufacturer or authorized distributors?
All SZMMSZ5251ET1G 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 SZMMSZ5251ET1G meets industry standards.
7.What is the process for return or replacement of SZMMSZ5251ET1G?
All SZMMSZ5251ET1G units undergo pre-shipment inspection (PSI). If there is an issue with SZMMSZ5251ET1G, 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 SZMMSZ5251ET1G part is unused and in its original packaging.
Return procedure for SZMMSZ5251ET1G:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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