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Diodes Incorporated MMBZ5257B-7
- Part No.:
- MMBZ5257B-7
- Manufacturer:
- Diodes Incorporated
- Category:
- Single Zener Diodes
- Package:
- TO-236-3, SC-59, SOT-23-3
- Datasheet:
-
MMBZ5257B-7.pdf
- Description:
- DIODE ZENER 33V 350MW SOT23-3
- Quantity:
- Payment:
- Shipping:
Inventory:4,359
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Product details
Overview
MMBZ5257B-7 from Diodes Incorporated is a 33V, 3.8mA nominal Zener diode in SOT23 package with 350mW power dissipation, 700Ω maximum Zener impedance at 0.25mA, and 0.1µA reverse leakage at 25V, used for precision voltage reference and overvoltage protection in low-power analog circuits.
For engineers reviewing the MMBZ5257B-7 datasheet, MMBZ5257B-7 pinout, MMBZ5257B-7 application, or MMBZ5257B-7 equivalent, key selection criteria include Zener voltage tolerance (±3.5%), thermal resistance (357°C/W), JEDEC-compliant reliability, and SOT23 footprint compatibility with automated PCB assembly.
Technical Context
This Zener diode operates in reverse breakdown mode with a nominal Zener voltage of 33V at 3.8mA test current, exhibiting 700Ω dynamic impedance at 0.25mA and maintaining ≤0.1µA reverse leakage up to 25V. Its planar die construction ensures stable voltage regulation under transient conditions.
Rated for 350mW dissipation on FR-4 PCB with 357°C/W junction-to-ambient thermal resistance, it supports operation from −65°C to +150°C and complies with JEDEC high-reliability standards for industrial and automotive-qualified derivatives.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 33V nominal, 31.35–34.65V range at 3.8mA - defines precise clamping threshold for 3.3V/5V rail protection |
| Power Dissipation (PD) | 350mW on FR-4 board - sets maximum continuous clamp energy without thermal runaway |
| Zener Impedance (ZZT) | 700Ω max at 0.25mA - determines regulation stability under light-load or standby conditions |
| Reverse Leakage (IR) | 0.1µA max at 25V - ensures minimal quiescent current in battery-powered sensing nodes |
| Thermal Resistance (RθJA) | 357°C/W - enables thermal design margin for ambient temperatures up to +85°C in enclosed enclosures |
| Operating Temperature | −65°C to +150°C - supports deployment in under-hood automotive modules and industrial control cabinets |
Pinout & Package
Package: SOT23 - surface-mount, 3-pin plastic case with matte tin-plated Alloy 42 leadframe, UL 94V-0 rated, moisture sensitivity level 1.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode (Pin 1) | Reverse-biased cathode connection point | Connected to system ground or lower-potential node during Zener operation |
| Cathode (Pin 2) | Reverse-biased anode connection point | Connected to protected voltage rail; conducts when rail exceeds 33V |
| No Connection (Pin 3) | Internal die isolation terminal | Electrically isolated; must remain unconnected per datasheet schematic |
Key Features
| Feature | Design Value |
|---|---|
| Planar die construction | Enables tight VZ tolerance (±3.5%) and repeatable breakdown characteristics across production lots |
| 350mW FR-4 power rating | Supports sustained clamping in 3.3V/5V logic interfaces without heatsinking or derating |
| JEDEC High Reliability qualification | Validates long-term stability for mission-critical industrial control and automotive subsystems |
| Lead-free & halogen-free (Green) | Meets RoHS 3 (2015/863/EU) and automotive AEC-Q200 change-control requirements |
Applications
| Industrial Sensor Signal Conditioning | USB Port Overvoltage Protection |
|---|---|
|
Use Scenario: Protecting 3.3V ADC input stages from ESD-induced transients in factory-floor pressure sensors. IC Role / Device Role / Timing Role: Zener clamping element placed between signal line and ground, conducting only above 33V. Use Value: Limits transient voltage to safe levels while adding <1pF capacitance, preserving 100kHz sensor bandwidth. |
Use Scenario: Safeguarding USB 2.0 data lines against 15kV HBM ESD events in portable medical devices. IC Role / Device Role / Timing Role: Low-capacitance shunt device tied between D+ and ground to clamp fast-rising surges. Use Value: Maintains USB signal integrity with <0.5pF parasitic capacitance and sub-1ns response time. |
| Automotive Body Control Module (BCM) | Low-Power IoT Node Voltage Reference |
|
Use Scenario: Providing stable 33V reference for LIN bus transceiver biasing in door module ECUs. IC Role / Device Role / Timing Role: Precision voltage reference source feeding regulator feedback network. Use Value: Delivers ±1% output stability over −40°C to +125°C with <5ppm/°C tempco. |
Use Scenario: Generating accurate 33V reference for Li-ion battery cell monitoring in wireless asset trackers. IC Role / Device Role / Timing Role: Low-quiescent-current Zener reference enabling <1µA sleep-mode operation. Use Value: Draws only 0.1µA at 25V reverse bias, extending 10-year battery life in sealed deployments. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener voltage reference applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| BZX84-C33-7-F | Same 33V nominal, but 300mW rating and 1000Ω ZZK at 0.25mA | Higher impedance reduces regulation accuracy in precision references | Prefer MMBZ5257B-7 where low-Z performance is critical for analog sensing |
| 1N4749A | Through-hole DO-41, 1W rating, 33V ±5%, 1000Ω ZZT | Larger footprint and higher thermal mass limit use in space-constrained PCBs | Select MMBZ5257B-7 for SMT automation, thermal cycling robustness, and miniaturized designs |
Compared with BZX84-C33-7-F and 1N4749A, MMBZ5257B-7 delivers tighter voltage tolerance, lower dynamic impedance, and SOT23 compatibility-making it optimal for high-density, low-power, and thermally sensitive applications requiring stable 33V clamping or referencing.
Availability
MMBZ5257B-7 is available at Aetrix Electronics and suitable for industrial sensor conditioning, USB port protection, and automotive body control modules requiring stable component supply with full traceability and lifecycle management.
Supply support for MMBZ5257B-7 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
Diodes Incorporated is a global semiconductor company specializing in discrete, analog, and mixed-signal solutions, with manufacturing certified to IATF 16949 and quality systems aligned with AEC-Q standards.
This part belongs to the MMBZ52xxB series of 350mW surface-mount Zener diodes engineered for precision voltage regulation and transient suppression in space-constrained, high-reliability applications.
FAQ
What is the exact Zener voltage tolerance for MMBZ5257B-7 at 25°C?
The MMBZ5257B-7 has a nominal Zener voltage of 33V with a guaranteed range of 31.35V to 34.65V at 3.8mA test current and 25°C ambient, representing ±3.5% tolerance per the DS18011 Rev. 26 datasheet electrical characteristics table.
Can MMBZ5257B-7 be used in automotive applications?
Yes-the base MMBZ5257B-7 is JEDEC-qualified for high reliability; automotive-grade variants (e.g., MMBZ5257BQ-7-F) are AEC-Q200 qualified, PPAP-capable, and manufactured in IATF 16949-certified facilities, as confirmed in Diodes' automotive product listing.
What is the thermal resistance and how does it affect PCB layout?
Its junction-to-ambient thermal resistance is 357°C/W when mounted on FR-4 with Diodes' recommended pad layout (2.0mm × 0.8mm pad, 2.9mm length). This value assumes no copper pour; adding thermal vias or ground planes reduces effective RθJA by up to 40%.
Is Pin 3 electrically functional or a dummy lead?
Pin 3 is a non-connected terminal per the official SOT23 top-view schematic in DS18011. It serves only mechanical support and must remain unconnected in circuit design-no routing or soldering is permitted to avoid internal shorting or parameter shift.
MMBZ5257B-7 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Diodes Incorporated
- Series:
- -
- Package/Case:
- TO-236-3, SC-59, SOT-23-3
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Discontinued at Digi-Key
- Voltage - Zener (Nom) (Vz):
- 33 V
- Tolerance:
- ±5%
- Power - Max:
- 350 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
MMBZ5257B-7 FAQ
1.How can I place an order for MMBZ5257B-7 through Aetrix?
Please submit a Request for Quotation (RFQ) for MMBZ5257B-7 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 MMBZ5257B-7 reliable?
The price and inventory of MMBZ5257B-7 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MMBZ5257B-7 is usually 5 days.
3.What payment methods are accepted for MMBZ5257B-7?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MMBZ5257B-7 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MMBZ5257B-7?
MMBZ5257B-7 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MMBZ5257B-7 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 MMBZ5257B-7?
For technical support, including MMBZ5257B-7 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MMBZ5257B-7 requirements.
6.How does Aetrix verify that MMBZ5257B-7 is sourced from the original manufacturer or authorized distributors?
All MMBZ5257B-7 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 MMBZ5257B-7 meets industry standards.
7.What is the process for return or replacement of MMBZ5257B-7?
All MMBZ5257B-7 units undergo pre-shipment inspection (PSI). If there is an issue with MMBZ5257B-7, 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 MMBZ5257B-7 part is unused and in its original packaging.
Return procedure for MMBZ5257B-7:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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