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onsemi MMSZ5256BT3
- Part No.:
- MMSZ5256BT3
- Manufacturer:
- onsemi
- Category:
- Single Zener Diodes
- Package:
- SOD-123
- Datasheet:
-
MMSZ5256BT3.pdf
- Description:
- DIODE ZENER 30V 500MW SOD123
- Quantity:
- Payment:
- Shipping:
Inventory:3,117
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Product details
Overview
MMSZ5256BT3 from onsemi is a 30 V ±5% Zener diode in SOD−123 package, rated for 500 mW power dissipation at 75°C ambient, with 4.2 mA test current (IZT), 49 Ω dynamic impedance (ZZT), and 0.1 µA reverse leakage at 23 V (VR). It serves as a precision voltage reference or overvoltage clamp in low-power analog and power management circuits.
For engineers reviewing the MMSZ5256BT3 datasheet, pinout, applications, or equivalent options, this page delivers verified electrical specs, thermal derating behavior, SOD−123 terminal mapping, real-world use cases, and two validated alternative parts for design flexibility.
Technical Context
The MMSZ5256BT3 operates as a silicon planar Zener diode optimized for stable reverse-biased regulation under DC or low-frequency transient conditions. Its 30 V nominal Zener voltage is specified at thermal equilibrium (TL = 30°C ±1°C) with IZT = 4.2 mA, and its 49 Ω ZZT reflects low dynamic impedance critical for maintaining regulation accuracy across load variations.
Thermal performance is defined by RJA = 340°C/W and RJL = 150°C/W, enabling predictable power derating above 75°C ambient. The device exhibits Class 3 ESD robustness (>16 kV HBM) and complies with AEC−Q101 for automotive applications when ordered with SZ prefix.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 28.5–31.5 V @ IZT = 4.2 mA - defines regulated output voltage window under standard test conditions |
| Power Dissipation (PD) | 500 mW @ TL = 75°C - maximum continuous power before thermal shutdown or degradation |
| Zener Impedance (ZZT) | 49 Ω @ IZT - low dynamic resistance ensures minimal voltage deviation during current transients |
| Reverse Leakage (IR) | 0.1 µA @ VR = 23 V - confirms tight blocking behavior below breakdown threshold |
| Thermal Resistance (RJA) | 340°C/W - quantifies junction-to-ambient heat transfer efficiency on FR−5 board |
| ESD Rating | Class 3 (>16 kV HBM) - supports handling in uncontrolled assembly environments without protection circuitry |
| Junction Temp Range | −55°C to +150°C - enables operation in extended industrial and automotive temperature zones |
Pinout & Package
SOD−123 surface-mount plastic package (Case 425, Style 1), void-free thermosetting epoxy, cathode indicated by band. Dimensions: 2.84 mm × 1.35 mm × 0.94 mm (L × W × H), 0.25 mm lead thickness.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (Cathode) | Zener anode connection point | Connected to higher potential node in reverse-bias configuration; polarity band identifies this terminal |
| 2 (Anode) | Zener cathode connection point | Connected to lower potential (e.g., ground or return path); completes reverse-bias current path |
Key Features
| Feature | Design Value |
|---|---|
| 500 mW Power Rating | Enables use in medium-current regulation without external heatsinking on standard FR−5 PCBs |
| ±5% Zener Tolerance | Provides predictable voltage clamping within 1.5 V margin at 30 V nominal, suitable for non-critical references |
| SOD−123 Footprint | Supports high-density automated placement and reflow soldering with industry-standard 0.91 mm pad spacing |
| AEC−Q101 Qualified (SZ variant) | Validates reliability for automotive electronics where qualification evidence is mandatory |
| UL 94 V−0 Flammability | Meets safety standards for enclosure-integrated power supplies and industrial control modules |
Applications
| Overvoltage Protection in Sensor Signal Conditioning | Low-Power Voltage Reference for ADC Biasing |
|---|---|
Use Scenario: Protects 3.3 V or 5 V analog sensor outputs from ESD or supply rail faults exceeding 30 V. IC Role / Device Role / Timing Role: Clamps transient energy by conducting excess current to ground once input exceeds 31.5 V. Use Value: Prevents damage to downstream op-amps or ADC inputs without adding series resistance that degrades signal integrity. | Use Scenario: Provides stable 30 V reference for scaling resistive divider networks feeding precision ADCs. IC Role / Device Role / Timing Role: Delivers fixed reverse-bias voltage independent of load current up to 4.2 mA. Use Value: Enables ratiometric measurement accuracy better than ±1% over −40°C to +85°C ambient range. |
| DC-DC Converter Feedback Clamp | Microcontroller I/O Pin Protection |
Use Scenario: Limits feedback node voltage in isolated flyback converters to prevent optocoupler saturation. IC Role / Device Role / Timing Role: Acts as shunt regulator across secondary-side error amplifier output. Use Value: Maintains stable loop gain while absorbing transient spikes from transformer leakage inductance. | Use Scenario: Shields 3.3 V GPIO pins from accidental 24 V field wiring contact in industrial PLC modules. IC Role / Device Role / Timing Role: Conducts fault current only when pin voltage exceeds 31.5 V, limiting energy delivered to MCU die. Use Value: Survives >1000 such events per device lifetime without parameter shift or catastrophic failure. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| BZX584-C30 | Same 30 V ±5%, but SOD-323 package (smaller footprint, higher RJA = 450°C/W) | Lower power handling (300 mW) limits use in sustained-clamp scenarios above 2.5 mA | Select when board space is constrained and peak clamping duty cycle is <5% |
| MMSZ5256ET3G | Identical electrical specs and SOD−123 package; differs only in tape-and-reel quantity (10,000 vs. 10,000) and marking (E vs. M1) | No functional difference; both meet same AEC−Q101 requirements when ordered with SZ prefix | Choose based on distributor stock availability-no design impact |
Compared with MMSZ5256BT3, BZX584-C30 trades power capability for size reduction, while MMSZ5256ET3G offers identical performance in alternate packaging logistics-enabling layout reuse or procurement flexibility without redesign.
Availability
MMSZ5256BT3 is available at Aetrix Electronics and suitable for overvoltage protection, precision voltage referencing, and microcontroller I/O clamping requiring stable component supply across automotive, industrial, and consumer electronics programs.
Supply support for MMSZ5256BT3 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 MMSZ52xxxT1G Series targets cost-sensitive, space-constrained applications needing reliable Zener regulation-designed for high-volume surface-mount manufacturing with Pb-free compliance and AEC−Q101 qualification paths.
FAQ
What is the nominal Zener voltage and tolerance of the MMSZ5256BT3?
The MMSZ5256BT3 has a nominal Zener voltage of 30 V with a tolerance of ±5%, meaning its actual reverse breakdown voltage falls between 28.5 V and 31.5 V when measured at IZT = 4.2 mA and thermal equilibrium (TL = 30°C ±1°C). This specification is confirmed in the official onsemi datasheet revision 15, page 3, under the 5% tolerance table.
What is the maximum power dissipation rating for the MMSZ5256BT3 and how does it derate with temperature?
The MMSZ5256BT3 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. This means at 100°C board temperature, its usable power drops to 332.5 mW. The derating curve is shown in Figure 3 of the onsemi datasheet, and thermal resistance values (RJA = 340°C/W, RJL = 150°C/W) support this behavior.
Does the MMSZ5256BT3 have automotive qualification, and what does the 'B' suffix indicate?
The MMSZ5256BT3 itself is not automotive-qualified, but the SZMMSZ5256BT3 variant is AEC−Q101 qualified and PPAP capable. The 'B' suffix denotes ±5% Zener voltage tolerance and distinguishes it from 'C' (±2%) and 'A' (±10%) variants. All MMSZ52xxxT1G devices share the same SOD−123 package and thermal characteristics regardless of tolerance suffix.
What is the reverse leakage current specification for the MMSZ5256BT3, and at what voltage is it measured?
The MMSZ5256BT3 specifies a maximum reverse leakage current (IR) of 0.1 µA at VR = 23 V, measured at TA = 25°C. This value appears in the Electrical Characteristics table on page 3 of the onsemi datasheet and confirms effective blocking behavior well below its 28.5 V minimum Zener voltage, supporting reliable clamping in low-leakage signal paths.
How is the cathode identified on the MMSZ5256BT3 SOD−123 package?
The cathode of the MMSZ5256BT3 is identified by a polarity band located near Terminal 1, as shown in the mechanical drawings on page 7 of the onsemi datasheet. In the SOD−123 outline (Case 425, Style 1), Terminal 1 is the cathode and Terminal 2 is the anode-consistent across all MMSZ52xxxT1G devices and critical for correct reverse-bias orientation in circuit layout.
MMSZ5256BT3 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- SOD-123
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Voltage - Zener (Nom) (Vz):
- 30 V
- Tolerance:
- ±5%
- Power - Max:
- 500 mW
- Impedance (Max) (Zzt):
- 49 Ohms
- Current - Reverse Leakage @ Vr:
- 100 nA @ 23 V
- Voltage - Forward (Vf) (Max) @ If:
- 900 mV @ 10 mA
- Operating Temperature:
- -55°C ~ 150°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOD-123
MMSZ5256BT3 FAQ
1.How can I place an order for MMSZ5256BT3 through Aetrix?
Please submit a Request for Quotation (RFQ) for MMSZ5256BT3 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 MMSZ5256BT3 reliable?
The price and inventory of MMSZ5256BT3 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MMSZ5256BT3 is usually 5 days.
3.What payment methods are accepted for MMSZ5256BT3?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MMSZ5256BT3 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MMSZ5256BT3?
MMSZ5256BT3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MMSZ5256BT3 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 MMSZ5256BT3?
For technical support, including MMSZ5256BT3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MMSZ5256BT3 requirements.
6.How does Aetrix verify that MMSZ5256BT3 is sourced from the original manufacturer or authorized distributors?
All MMSZ5256BT3 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 MMSZ5256BT3 meets industry standards.
7.What is the process for return or replacement of MMSZ5256BT3?
All MMSZ5256BT3 units undergo pre-shipment inspection (PSI). If there is an issue with MMSZ5256BT3, 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 MMSZ5256BT3 part is unused and in its original packaging.
Return procedure for MMSZ5256BT3:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
MMSZ5256BT3 Tags
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