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onsemi MMBZ5257BLT1
- Part No.:
- MMBZ5257BLT1
- Manufacturer:
- onsemi
- Category:
- Single Zener Diodes
- Package:
- TO-236-3, SC-59, SOT-23-3
- Datasheet:
-
MMBZ5257BLT1.pdf
- Description:
- DIODE ZENER 33V 225MW SOT23
- Quantity:
- Payment:
- Shipping:
Inventory:2,838
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Product details
Overview
MMBZ5257BLT1 from onsemi is a 33 V, 225 mW surface-mount Zener diode in SOT-23 package, designed for precision voltage regulation and overvoltage protection in space-constrained circuits. It delivers nominal Zener voltage of 33 V at 3.8 mA test current, with dynamic impedance of 58 Ω and leakage current ≤0.1 μA at 25 V reverse bias, commonly used in portable power rail clamping and reference stabilization.
For engineers reviewing the MMBZ5257BLT1 datasheet, pinout, applications, or equivalent options, key selection criteria include Zener voltage tolerance (±3.5%), thermal resistance (556 °C/W on FR-5), ESD rating (>16 kV HBM), and SOT-23 footprint compatibility with automated assembly.
Technical Context
This device operates as a two-terminal voltage reference diode with cathode-anode polarity, requiring no external biasing. Its Zener breakdown mechanism provides stable regulation across −65 °C to +150 °C junction temperature range, with temperature coefficient near zero at ~33 V (confirmed by typical TC curve crossing 0 mV/°C between 30–35 V).
It exhibits low forward voltage (≤0.9 V at 10 mA) and high ESD robustness (Class 3 HBM), making it suitable for transient suppression in battery-powered interfaces. The NC (pin 2) terminal eliminates parasitic coupling and simplifies PCB layout versus three-terminal alternatives.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 33 V nominal at IZT = 3.8 mA - defines precise clamping threshold for 3.3 V or 5 V rail protection |
| Power Dissipation | 225 mW on FR-5 board - supports continuous regulation in handheld PCBs without heatsinking |
| Zener Impedance (ZZT) | 58 Ω at IZT - ensures minimal output voltage shift under load transients up to ±1 mA |
| Leakage Current (IR) | ≤0.1 μA at VR = 25 V - prevents measurable current draw in standby mode of low-power systems |
| ESD Rating | Class 3 (>16 kV HBM) - withstands direct human-body discharge events without degradation |
| Junction Temp Range | −65 °C to +150 °C - enables operation in automotive under-hood and industrial motor-control environments |
| Package | SOT-23 (Case 318) - 2.9 mm × 1.3 mm footprint compatible with standard pick-and-place equipment |
Pinout & Package
SOT-23 plastic surface-mount package with void-free thermosetting case, corrosion-resistant finish, and UL 94 V-0 flammability rating. Cathode indicated by band; pin 2 is internally unconnected.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | Anode | Connected to lower-potential node; reverse-biased during regulation |
| 2 | No Connection | Internally isolated - must remain floating; no PCB trace or pad required |
| 3 | Cathode | Connected to regulated voltage node; carries full Zener current during clamp event |
Key Features
| Feature | Design Value |
|---|---|
| Pb-Free, Halogen-Free, RoHS Compliant | Meets global environmental compliance mandates without derating or process change |
| Optimized for Automated Assembly | SOT-23 geometry and marking support high-yield reflow and vision-based placement verification |
| Low Capacitance | ~10 pF at 50% VZ - minimizes signal integrity impact in high-frequency data line protection |
| Stable Zener Voltage Tolerance | ±3.5% (31.35 V to 34.65 V) - enables accurate threshold setting without post-production trimming |
| High-Temp Reliability | Rated to +150 °C junction - sustains regulation performance in thermally dense DC-DC converter layouts |
Applications
| USB Power Input Protection | Microcontroller I/O Clamp |
|---|---|
|
Use Scenario: Clamping 5 V USB VBUS against surge events in portable accessories. IC Role / Device Role / Timing Role: Two-terminal shunt regulator absorbing transient energy above 33 V while holding downstream LDO input within safe range. Use Value: Prevents damage to USB interface ICs during hot-plug or ESD events without adding series resistance or delay. |
Use Scenario: Protecting 3.3 V GPIO pins from accidental 5 V misconnection or inductive kickback. IC Role / Device Role / Timing Role: Fast-acting voltage clamp limiting pin voltage to ≤34.65 V, well below absolute maximum ratings of most MCUs. Use Value: Eliminates need for external series resistors or TVS arrays, reducing BOM count and board area. |
| Portable Battery Monitor Reference | Industrial Sensor Signal Conditioning |
|
Use Scenario: Providing stable 33 V reference for ADC measurement of Li-ion battery pack voltage (12–48 V range). IC Role / Device Role / Timing Role: Precision Zener reference source with <0.1 μA leakage ensuring minimal loading on high-impedance divider networks. Use Value: Enables accurate state-of-charge estimation without calibration drift from temperature or aging effects. |
Use Scenario: Regulating excitation voltage for 4–20 mA loop-powered pressure sensors in factory automation. IC Role / Device Role / Timing Role: Low-noise, low-drift voltage stabilizer maintaining constant sensor bias despite supply ripple or load variation. Use Value: Improves measurement repeatability by reducing excitation voltage dependency on 24 V rail fluctuations. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| BZX84-C33 | Same 33 V nominal, but 300 mW rating and higher ZZT (90 Ω); SOT-23 package with pin 2 connected to cathode | Higher power handling suits sustained overvoltage events; pin 2 connection requires layout revision | Select when >225 mW dissipation margin is needed and cathode tie-out is acceptable |
| MMBZ5257BS | Identical electrical specs, but in SOD-123 package (larger footprint, higher thermal mass) | Lower thermal resistance (417 °C/W on alumina) improves reliability in high-ambient-temp industrial settings | Select when board space allows larger package and enhanced thermal performance is prioritized over miniaturization |
Compared with BZX84-C33 and MMBZ5257BS, MMBZ5257BLT1 offers optimal balance of ultra-compact SOT-23 size, Class 3 ESD robustness, and tight 3.5% voltage tolerance-making it preferred for high-density portable designs where pin 2 isolation and automated assembly yield are critical.
Availability
MMBZ5257BLT1 is available at Aetrix Electronics and suitable for USB power protection, microcontroller I/O clamping, portable battery monitoring, and industrial sensor signal conditioning requiring stable component supply and consistent parametric performance.
Supply support for MMBZ5257BLT1 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 specializing in energy-efficient silicon solutions for automotive, industrial, cloud, and IoT applications.
The MMBZ52xxBLT1G series was developed to deliver reliable, miniature Zener regulation for high-density portable electronics-emphasizing ESD hardness, Pb-free compliance, and SMT manufacturability.
FAQ
What is the Zener voltage tolerance of MMBZ5257BLT1?
The MMBZ5257BLT1 has a Zener voltage tolerance of ±3.5%, with minimum 31.35 V and maximum 34.65 V at 3.8 mA test current. This tight tolerance ensures predictable clamping behavior in precision reference and protection circuits without requiring post-layout calibration. The MMBZ5257BLT1 maintains this specification across its full operating temperature range.
Does MMBZ5257BLT1 require a heatsink in standard PCB layouts?
No, the MMBZ5257BLT1 does not require a heatsink when operated within its 225 mW power rating on FR-5 board. Its thermal resistance of 556 °C/W means it reaches only ~125 °C junction temperature at full rated power and 25 °C ambient-well within its −65 °C to +150 °C rating. The MMBZ5257BLT1 is optimized for natural convection cooling in compact consumer PCBs.
Is pin 2 of MMBZ5257BLT1 electrically connected?
No, pin 2 of the MMBZ5257BLT1 is internally unconnected (NC). Per the official datasheet mechanical outline (Style 8), pin 2 serves no electrical function and must remain floating on the PCB. This isolation reduces parasitic capacitance and simplifies routing compared to three-terminal Zeners where pin 2 connects to cathode or anode.
How does the ESD rating of MMBZ5257BLT1 compare to standard diodes?
The MMBZ5257BLT1 achieves Class 3 Human Body Model ESD rating (>16 kV), significantly exceeding typical general-purpose diodes (<8 kV). This robustness stems from onsemi's proprietary Zener process and passivation design. The MMBZ5257BLT1 can absorb repeated ESD strikes without parameter shift-critical for USB, audio jack, and button interface protection where user contact is frequent.
Can MMBZ5257BLT1 be used as a voltage reference in analog circuits?
Yes, the MMBZ5257BLT1 functions effectively as a low-cost, low-current voltage reference in analog circuits requiring ~33 V. Its 58 Ω dynamic impedance and <0.1 μA leakage at 25 V ensure stable output under light loads (<1 mA). For best accuracy, use with a current-limiting resistor to maintain IZ near 3.8 mA; the MMBZ5257BLT1's temperature coefficient crosses zero near 33 V, minimizing drift.
MMBZ5257BLT1 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- TO-236-3, SC-59, SOT-23-3
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Voltage - Zener (Nom) (Vz):
- 33 V
- Tolerance:
- ±5%
- Power - Max:
- 225 mW
- Impedance (Max) (Zzt):
- 58 Ohms
- Current - Reverse Leakage @ Vr:
- 100 nA @ 25 V
- Voltage - Forward (Vf) (Max) @ If:
- 900 mV @ 10 mA
- Operating Temperature:
- -65°C ~ 150°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-23-3 (TO-236)
MMBZ5257BLT1 FAQ
1.How can I place an order for MMBZ5257BLT1 through Aetrix?
Please submit a Request for Quotation (RFQ) for MMBZ5257BLT1 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 MMBZ5257BLT1 reliable?
The price and inventory of MMBZ5257BLT1 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MMBZ5257BLT1 is usually 5 days.
3.What payment methods are accepted for MMBZ5257BLT1?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MMBZ5257BLT1 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MMBZ5257BLT1?
MMBZ5257BLT1 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MMBZ5257BLT1 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 MMBZ5257BLT1?
For technical support, including MMBZ5257BLT1 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MMBZ5257BLT1 requirements.
6.How does Aetrix verify that MMBZ5257BLT1 is sourced from the original manufacturer or authorized distributors?
All MMBZ5257BLT1 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 MMBZ5257BLT1 meets industry standards.
7.What is the process for return or replacement of MMBZ5257BLT1?
All MMBZ5257BLT1 units undergo pre-shipment inspection (PSI). If there is an issue with MMBZ5257BLT1, 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 MMBZ5257BLT1 part is unused and in its original packaging.
Return procedure for MMBZ5257BLT1:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
MMBZ5257BLT1 Tags
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