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Diodes Incorporated MMBZ5257B-7-F
- Part No.:
- MMBZ5257B-7-F
- Manufacturer:
- Diodes Incorporated
- Category:
- Single Zener Diodes
- Package:
- TO-236-3, SC-59, SOT-23-3
- Datasheet:
-
MMBZ5257B-7-F.pdf
- Description:
- DIODE ZENER 33V 350MW SOT23-3
- Quantity:
- Payment:
- Shipping:
Inventory:6,069
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Product details
Overview
MMBZ5257B-7-F from Diodes Incorporated is a 33 V, ±3% tolerance, 350 mW surface-mount Zener diode in SOT23 package, optimized for voltage regulation and overvoltage protection in low-power analog circuits, with 58 Ω dynamic impedance at 3.8 mA test current and 0.1 µA reverse leakage at 25 V.
For engineers reviewing the MMBZ5257B-7-F datasheet, MMBZ5257B-7-F pinout, MMBZ5257B-7-F application, or MMBZ5257B-7-F equivalent, this part serves as a precision shunt reference in power supply feedback loops, ESD-clamped I/O protection, and low-current biasing networks where stable breakdown voltage and tight tolerance are critical.
Technical Context
This Zener diode operates in reverse-biased breakdown mode with a nominal Zener voltage of 33 V, specified at 3.8 mA test current (IZT), and exhibits a maximum Zener impedance of 58 Ω at IZT and 700 Ω at knee current (IZK = 0.25 mA). Its thermal resistance (RθJA) is 357 °C/W on FR-4 PCB, enabling reliable operation up to +150 °C junction temperature.
The device uses planar die construction and matte tin–plated alloy 42 leadframe for solderability per MIL-STD-202, Method 208. It is fully RoHS-compliant, halogen- and antimony-free ("Green"), and rated for moisture sensitivity level 1 per J-STD-020.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 33 V nominal, 31.35–34.65 V range at 3.8 mA - ensures precise voltage clamping in feedback and reference circuits |
| Power Dissipation (PD) | 350 mW on FR-4 PCB - defines maximum continuous power handling under standard layout conditions |
| Zener Impedance (ZZT) | 58 Ω at 3.8 mA - determines regulation stability under small-signal load variations |
| Reverse Leakage (IR) | 0.1 µA at 25 V - guarantees minimal quiescent current in high-impedance bias networks |
| Forward Voltage (VF) | 0.9 V at 10 mA - enables use as low-drop rectifier or clamp in bidirectional protection schemes |
| Operating Temperature | −65 °C to +150 °C - supports deployment in industrial and automotive under-hood environments |
Pinout & Package
Package: SOT23 - compact 3-pin surface-mount plastic package with 0.915 mm lead pitch, 2.40 mm body length, and 1.30 mm body width; UL 94V-0 rated molding compound.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode (Pin 1) | Forward conduction terminal / cathode reference ground path | Connected to circuit ground or lower-potential node when used in shunt regulation |
| Cathode (Pin 2) | Zener breakdown terminal / regulated output node | Connected to input rail or signal line requiring clamping; carries full Zener current during regulation |
| No Connect (Pin 3) | Internal die attach pad / thermal slug (non-functional) | Not electrically connected; may be left floating or tied to ground for thermal enhancement per layout guidelines |
Key Features
| Feature | Design Value |
|---|---|
| Planar die construction | Enables tight Zener voltage tolerance (±3%) and repeatable breakdown characteristics across production lots |
| 350 mW dissipation on FR-4 | Supports direct integration into standard PCB layouts without heatsinking in ≤100 mA bias applications |
| Matte tin–plated leadframe | Ensures robust solder joint integrity and compatibility with lead-free reflow profiles (J-STD-020 Level 1) |
| Halogen- and antimony-free "Green" compound | Meets global environmental compliance mandates (RoHS 3, JEDEC High Reliability standards) without performance trade-offs |
Applications
| Industrial Sensor Signal Conditioning | USB Port ESD Protection |
|---|---|
|
Use Scenario: Stabilizing reference voltage for 24-bit ADC front-end in pressure transducers operating from 24 V DC rails. IC Role / Device Role / Timing Role: Shunt Zener reference providing 33 V rail clamp and bias point for op-amp gain-setting network. Use Value: ±3% VZ tolerance and 58 Ω ZZT ensure <0.5 LSB error contribution across −40 °C to +85 °C ambient. |
Use Scenario: Secondary-level transient suppression on USB VBUS line in portable medical monitors. IC Role / Device Role / Timing Role: Low-leakage (0.1 µA @ 25 V) clamping diode placed between VBUS and GND to absorb IEC 61000-4-2 ±8 kV contact discharge energy. Use Value: 350 mW rating and fast turn-on enable effective energy diversion without latch-up or thermal runaway. |
| Programmable Logic Controller I/O Protection | Low-Power IoT Node Voltage Reference |
|
Use Scenario: Protecting 24 V digital input channels against field-wiring transients in factory automation PLC modules. IC Role / Device Role / Timing Role: Zener clamp placed across optocoupler input LED to limit reverse voltage and prevent LED degradation. Use Value: 33 V breakdown precisely matches common 24 V system margin, preventing false triggering while surviving sustained overvoltages. |
Use Scenario: Generating stable 33 V bias for RF power amplifier biasing in battery-powered LoRaWAN gateways. IC Role / Device Role / Timing Role: Precision shunt regulator supplying fixed current to cascode transistor base via series resistor. Use Value: Low 0.1 µA IR minimizes standby current drain; 350 mW rating accommodates burst-mode PA operation without derating. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| BZX84-C33-7-F | Same 33 V nominal, but ±5% tolerance and 600 mW rating on FR-4; higher ZZT (80 Ω at 5 mA) | Higher power handling suits higher-current bias networks; looser tolerance limits use in precision references | Select when >350 mW dissipation or relaxed voltage accuracy is acceptable |
| MMBZ5257BS-7-F | Identical electrical specs but SOT-323 package (smaller footprint, higher RθJA = 450 °C/W) | Preferred for ultra-dense layouts; requires tighter thermal management due to reduced heat spreading | Select when board space is constrained and thermal design accommodates higher junction rise |
Compared with BZX84-C33-7-F and MMBZ5257BS-7-F, MMBZ5257B-7-F delivers tighter voltage tolerance and lower thermal resistance in the industry-standard SOT23 footprint-making it optimal for cost-sensitive, precision-regulated industrial and IoT designs where layout flexibility and thermal performance are balanced.
Availability
MMBZ5257B-7-F is available at Aetrix Electronics and suitable for industrial sensor conditioning, USB port protection, PLC I/O safeguarding, and low-power IoT voltage referencing requiring stable component supply and long-term lifecycle support.
Supply support for MMBZ5257B-7-F 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 manufacturer of discrete semiconductors and analog ICs, specializing in high-reliability components for industrial, automotive, and consumer markets.
This part belongs to the MMBZ52xxB Zener diode family, engineered for precision voltage regulation and transient suppression in space-constrained, high-volume surface-mount applications.
FAQ
What is the maximum Zener test current (IZT) for MMBZ5257B-7-F?
The maximum Zener test current is 3.8 mA, at which the nominal 33 V breakdown voltage is specified with ±3% tolerance. This current defines the operating point for datasheet VZ, ZZT, and temperature coefficient measurements, and must not be exceeded continuously without thermal derating per Figure 1.
Can MMBZ5257B-7-F be used in automotive applications?
Yes, but only the Q-suffix automotive-grade variants (e.g., MMBZ5257BQ-7-F) are qualified to AEC-Q101 and manufactured in IATF 16949 certified facilities. The standard MMBZ5257B-7-F lacks PPAP documentation and automotive change control, so it is restricted to industrial and commercial use.
How does the SOT23 package affect thermal performance?
The SOT23 package provides a thermal resistance of 357 °C/W (junction-to-ambient) on FR-4 PCB with recommended pad layout. This allows safe operation up to 350 mW at +25 °C ambient, but requires linear derating above +25 °C per Figure 1-e.g., ~250 mW at +70 °C ambient.
Is the third pin (Pin 3) electrically functional?
No, Pin 3 is an internal die attach pad with no electrical connection. It may be left unconnected or tied to ground for improved thermal conduction, but doing so does not alter electrical behavior or Zener characteristics as confirmed in Diodes' package outline DS18011 Rev. 26-2.
MMBZ5257B-7-F 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:
- Active
- 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-F FAQ
1.How can I place an order for MMBZ5257B-7-F through Aetrix?
Please submit a Request for Quotation (RFQ) for MMBZ5257B-7-F 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-F reliable?
The price and inventory of MMBZ5257B-7-F 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-F is usually 5 days.
3.What payment methods are accepted for MMBZ5257B-7-F?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MMBZ5257B-7-F transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MMBZ5257B-7-F?
MMBZ5257B-7-F orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MMBZ5257B-7-F 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-F?
For technical support, including MMBZ5257B-7-F datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MMBZ5257B-7-F requirements.
6.How does Aetrix verify that MMBZ5257B-7-F is sourced from the original manufacturer or authorized distributors?
All MMBZ5257B-7-F 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-F meets industry standards.
7.What is the process for return or replacement of MMBZ5257B-7-F?
All MMBZ5257B-7-F units undergo pre-shipment inspection (PSI). If there is an issue with MMBZ5257B-7-F, 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-F part is unused and in its original packaging.
Return procedure for MMBZ5257B-7-F:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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