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Diodes Incorporated MMBZ5238B-7-F
- Part No.:
- MMBZ5238B-7-F
- Manufacturer:
- Diodes Incorporated
- Category:
- Single Zener Diodes
- Package:
- TO-236-3, SC-59, SOT-23-3
- Datasheet:
-
MMBZ5238B-7-F.pdf
- Description:
- DIODE ZENER 8.7V 350MW SOT23-3
- Quantity:
- Payment:
- Shipping:
Inventory:5,783
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Product details
Overview
MMBZ5238B-7-F from Diodes Incorporated is a 350mW surface-mount Zener diode with a nominal zener voltage of 8.7V (min 8.27V, max 9.14V at 20mA test current), 8Ω zener impedance at 20mA, and 3.0µA reverse leakage at 6.5V. It operates across –65°C to +150°C and is used for precision voltage regulation and overvoltage protection in low-power analog signal conditioning circuits.
For engineers reviewing the MMBZ5238B-7-F datasheet, MMBZ5238B-7-F pinout, MMBZ5238B-7-F application, or MMBZ5238B-7-F equivalent, this part is selected for stable reference generation in battery-powered sensors, I/O rail clamping in microcontroller peripherals, and low-current biasing in op-amp feedback networks where tight voltage tolerance and low dynamic impedance are required.
Technical Context
This Zener diode employs planar die construction for consistent breakdown characteristics and thermal stability. Its 350mW power dissipation rating is specified on FR-4 PCB with recommended pad layout, and thermal resistance is 357°C/W junction-to-ambient.
The device exhibits 8Ω dynamic impedance at 20mA test current and maintains ≤3.0µA reverse leakage at VR = 6.5V - enabling accurate voltage reference performance under light-load conditions typical in sensor front-ends and standby power monitoring.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (Nom) | 8.7 V - precise regulation point for 9V rail stabilization or 8.5–9V reference applications |
| Zener Voltage Range | 8.27–9.14 V @ 20mA - ±5% tolerance band ensures predictable clamping in production designs |
| Zener Impedance | 8 Ω @ 20mA - low dynamic resistance minimizes output voltage shift under varying load current |
| Reverse Leakage | 3.0 µA @ 6.5V - negligible error contribution in high-impedance reference divider networks |
| Power Dissipation | 350 mW on FR-4 - supports continuous operation in compact SOT23 footprint without forced cooling |
| Operating Temp | –65°C to +150°C - qualified for extended industrial and automotive under-hood environments |
| Package | SOT23 - standard 3-pin surface-mount package compatible with automated pick-and-place and reflow |
Pinout & Package
MMBZ5238B-7-F is housed in a standard SOT23 plastic package with matte tin-plated alloy 42 leadframe. Pin 1 is anode, Pin 2 is cathode, Pin 3 is not connected (NC) - confirmed per Diodes Incorporated SOT23 top-view schematic and mechanical drawings.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1 | Anode | Connected to lower-potential node; forward-biased during normal conduction, reverse-biased during zener operation |
| Pin 2 | Cathode | Connected to higher-potential node; zener breakdown occurs between cathode and anode when VR > VZ |
| Pin 3 | Not Connected | No internal bond wire; electrically isolated - must be left floating or grounded only if required by board-level EMI mitigation |
Key Features
| Feature | Design Value |
|---|---|
| Planar die construction | Ensures repeatable breakdown voltage and long-term stability under thermal cycling |
| 350mW dissipation on FR-4 | Enables direct integration into cost-sensitive consumer and industrial PCBs without heatsinking |
| Lead-free & RoHS 3 compliant | Meets global environmental regulations including EU 2015/863/EU for bromine/chlorine/antimony limits |
| Moisture Sensitivity Level 1 | Eliminates bake requirements before reflow, reducing manufacturing overhead and handling risk |
| Matte tin finish | Provides reliable solderability per MIL-STD-202, Method 208 without post-solder cleaning |
Applications
| Industrial Sensor Reference | Microcontroller I/O Clamp |
|---|---|
|
Use Scenario: Providing stable 8.7V reference for 12-bit ADC input scaling in temperature/humidity transmitters. IC Role / Device Role / Timing Role: Zener diode operating in reverse breakdown to fix reference node voltage independent of supply variation. Use Value: Maintains <±0.5% full-scale error across –40°C to +85°C ambient due to tight VZ tolerance and low ZZT. |
Use Scenario: Protecting GPIO pins of STM32L4-series MCUs against transient overvoltage from relay coil flyback or ESD events. IC Role / Device Role / Timing Role: Bidirectional clamping element limiting pin voltage to 8.7V + VF during positive transients and conducting reverse leakage <3µA during normal operation. Use Value: Prevents latch-up while adding <100pF capacitance - no signal integrity impact on 10MHz digital I/O lines. |
| Low-Power Bias Network | Backup Power Supervisor |
|
Use Scenario: Generating bias current for JFET-input op-amps in portable medical pulse oximeter analog front-ends. IC Role / Device Role / Timing Role: Current-source element via series resistor + zener, delivering stable 200µA bias current with <2% drift over battery discharge (3.0–4.2V). Use Value: Enables DC-coupled signal path with <1nA input offset drift - critical for sub-µV physiological signal amplification. |
Use Scenario: Monitoring main 9V supply rail in smart smoke detector to trigger brownout reset when voltage drops below 8.27V. IC Role / Device Role / Timing Role: Precision threshold detector feeding comparator input; VZ min defines guaranteed trip point under worst-case process/temp corners. Use Value: Guarantees reset assertion before MCU core voltage falls below 1.8V - eliminates undefined state during battery depletion. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener diode voltage regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| BZX84-C8V2 (Nexperia) | 8.2V nominal, ±5% tolerance, 80Ω Zener impedance @ 5mA - higher dynamic impedance than MMBZ5238B-7-F's 8Ω @ 20mA | Lower test current shifts operating point; less suitable for stable reference under variable load | Select when cost sensitivity outweighs regulation accuracy and dynamic response requirements |
| 1SMA5923BT3G (onsemi) | 8.7V nominal, ±5%, but in SMA package (higher thermal mass); 1.5W power rating - overqualified size and dissipation for SOT23-targeted designs | Larger footprint increases PCB area by 4×; requires different stencil and placement setup | Choose only if system-level thermal margin demands >350mW capability or legacy SMA compatibility is mandatory |
Compared with BZX84-C8V2 and 1SMA5923BT3G, MMBZ5238B-7-F delivers superior voltage regulation stability under load variation due to its 8Ω impedance at 20mA, fits standard SOT23 assembly workflows, and balances precision, size, and manufacturability for modern low-power embedded systems.
Availability
MMBZ5238B-7-F is available at Aetrix Electronics and suitable for industrial sensor reference, microcontroller I/O clamp, and low-power bias network applications requiring stable component supply across multi-year production cycles.
Supply support for MMBZ5238B-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, headquartered in Plano, Texas, with design, manufacturing, and sales operations across Asia, Europe, and North America.
This part belongs to the MMBZ52xxB series of 350mW Zener diodes designed specifically for space-constrained, high-reliability voltage regulation and protection in consumer, industrial, and automotive electronics.
FAQ
What is the maximum reverse voltage (VR) at which MMBZ5238B-7-F guarantees ≤3.0µA leakage?
The datasheet specifies 3.0µA maximum reverse leakage current at VR = 6.5V. This value is measured under standard test conditions (TA = +25°C) and defines the upper bound of parasitic current draw when the diode is used as a shunt reference below its zener knee - critical for ultra-low-power battery applications.
Can MMBZ5238B-7-F be used in place of a 9.1V Zener like MMBZ5239B-F?
No - MMBZ5238B-7-F has a nominal zener voltage of 8.7V (8.27–9.14V range), while MMBZ5239B-F is rated at 9.1V (8.65–9.56V). Substituting them alters regulation setpoint by ~4.5%, potentially violating system voltage margin requirements; replacement requires validation of downstream circuit tolerance to that shift.
Is MMBZ5238B-7-F qualified for automotive applications?
MMBZ5238B-7-F itself is not AEC-Q200 qualified; however, Diodes Incorporated offers automotive-grade equivalents with Q-suffix (e.g., MMBZ5238BQ-7-F) manufactured in IATF 16949-certified facilities and qualified to AEC-Q200 standards - these must be specified separately for automotive use cases.
What is the thermal resistance (RθJA) of MMBZ5238B-7-F on a standard FR-4 PCB?
The thermal resistance from junction to ambient is 357°C/W when mounted on FR-4 PCB using Diodes Incorporated's recommended pad layout. This value assumes natural convection cooling and defines the temperature rise per milliwatt dissipated - essential for calculating maximum safe DC current under worst-case ambient conditions.
MMBZ5238B-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):
- 8.7 V
- Tolerance:
- ±5%
- Power - Max:
- 350 mW
- Impedance (Max) (Zzt):
- 8 Ohms
- Current - Reverse Leakage @ Vr:
- 3 µA @ 6.5 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
MMBZ5238B-7-F FAQ
1.How can I place an order for MMBZ5238B-7-F through Aetrix?
Please submit a Request for Quotation (RFQ) for MMBZ5238B-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 MMBZ5238B-7-F reliable?
The price and inventory of MMBZ5238B-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 MMBZ5238B-7-F is usually 5 days.
3.What payment methods are accepted for MMBZ5238B-7-F?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MMBZ5238B-7-F transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MMBZ5238B-7-F?
MMBZ5238B-7-F orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MMBZ5238B-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 MMBZ5238B-7-F?
For technical support, including MMBZ5238B-7-F datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MMBZ5238B-7-F requirements.
6.How does Aetrix verify that MMBZ5238B-7-F is sourced from the original manufacturer or authorized distributors?
All MMBZ5238B-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 MMBZ5238B-7-F meets industry standards.
7.What is the process for return or replacement of MMBZ5238B-7-F?
All MMBZ5238B-7-F units undergo pre-shipment inspection (PSI). If there is an issue with MMBZ5238B-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 MMBZ5238B-7-F part is unused and in its original packaging.
Return procedure for MMBZ5238B-7-F:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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