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onsemi MMBZ5239B
- Part No.:
- MMBZ5239B
- Manufacturer:
- onsemi
- Category:
- Single Zener Diodes
- Package:
- TO-236-3, SC-59, SOT-23-3
- Datasheet:
-
MMBZ5239B.pdf
- Description:
- DIODE ZENER 9.1V 300MW SOT23
- Quantity:
- Payment:
- Shipping:
Inventory:27,000
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Product details
Overview
MMBZ5239B from Fairchild Semiconductor is a 9.1 V ±5% surface-mount Zener diode in SOT-23 package, rated for 20 mA test current, 8.0 Ω dynamic impedance at 20 mA, and 3.0 μA maximum reverse leakage at 7.0 V, used for precision voltage regulation and overvoltage protection in low-power analog circuits.
For engineers reviewing the MMBZ5239B datasheet, pinout, applications, or equivalent options, this page provides verified electrical parameters, thermal characteristics, SOT-23 terminal mapping, and direct alternative options for voltage reference and clamping designs.
Technical Context
The MMBZ5239B operates as a silicon planar Zener diode with sharp reverse breakdown at nominal 9.1 V, optimized for stable DC voltage reference under 20 mA bias. Its 8.0 Ω Zener impedance ensures minimal output voltage variation across load changes in regulated supply rails.
Designed for operation up to +150°C junction temperature, it features 465°C/W junction-to-ambient thermal resistance on FR-4 PCB and 220°C/W junction-to-cathode lead thermal resistance-enabling reliable performance in compact, thermally constrained layouts.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 8.645–9.555 V at IZ = 20 mA - defines tight 9.1 V ±5% regulation window for reference stability |
| Zener Impedance (ZZ) | 8.0 Ω max at IZ = 20 mA - ensures <10 mV output shift per 1 mA load change in shunt regulator designs |
| Reverse Leakage (IR) | 3.0 μA max at VR = 7.0 V - guarantees low standby power loss in battery-powered voltage monitor circuits |
| Power Dissipation (PD) | 250 mW at TA = 25°C - supports continuous operation in ambient temperatures ≤70°C without derating |
| Forward Voltage (VF) | 0.9 V max at IF = 10 mA - enables use as bidirectional ESD clamp when paired with series resistor |
| Junction Temperature (TJ) | +150°C max - allows deployment in industrial control modules with localized heating near power components |
Pinout & Package
SOT-23 plastic surface-mount package with gull-wing leads; cathode marked by band on lead 3; terminals are anode (pin 1), cathode (pin 3), and NC (pin 2).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1 | Anode | Connected to lower-potential node in reverse-bias configuration; carries full Zener current during regulation |
| Pin 2 | No Connection | Internally unconnected; must remain floating-no routing or soldering required |
| Pin 3 | Cathode | Connected to higher-potential node; serves as voltage reference output point in shunt regulator topologies |
Key Features
| Feature | Design Value |
|---|---|
| ±5% Zener tolerance | Enables single-supply 9.1 V reference without post-assembly trimming in cost-sensitive consumer electronics |
| Low ZZ (8.0 Ω) | Maintains regulation accuracy within ±0.1 V across 5–25 mA load range in feedback-sensing applications |
| SOT-23 footprint | Reduces PCB area by >60% vs. DO-35, supporting high-density layout in space-constrained IoT sensor nodes |
| 150°C max TJ | Eliminates need for thermal relief pads in automotive cabin modules operating near HVAC ducts |
Applications
| Industrial Sensor Signal Conditioning | USB Port Overvoltage Protection |
|---|---|
Use Scenario: Stabilizing excitation voltage for bridge-based pressure transducers in factory automation PLC I/O modules. IC Role / Device Role / Timing Role: Shunt voltage reference providing fixed 9.1 V bias to Wheatstone bridge, rejecting supply ripple. Use Value: Maintains bridge output linearity within ±0.2% FSO despite ±10% input rail variation due to low ZZ and tight VZ tolerance. |
Use Scenario: Clamping transient surges on USB VBUS line during hot-plug events in embedded host controllers. IC Role / Device Role / Timing Role: Bidirectional ESD suppressor leveraging forward conduction (0.9 V) and reverse Zener action (9.1 V). Use Value: Limits VBUS spikes to <9.5 V during 8 kV contact discharge, preventing damage to USB PHY ICs rated for 5.5 V absolute max. |
| Programmable Logic Controller Input Protection | Low-Power MCU Reset Circuit |
Use Scenario: Protecting 24 V digital input channels against field-wiring faults and inductive kickback in industrial PLCs. IC Role / Device Role / Timing Role: Zener clamp referenced to local ground, diverting fault current away from optocoupler input LED. Use Value: Absorbs 250 mW surge energy without degradation, enabling compliance with IEC 61000-4-4 Level 3 (2 kV fast transient burst). |
Use Scenario: Generating precise reset threshold for 3.3 V microcontrollers in battery-operated smart meters. IC Role / Device Role / Timing Role: Voltage divider element with resistor to set 2.7 V reset trigger, leveraging stable 9.1 V reference. Use Value: Delivers ±1.5% reset threshold accuracy over –40°C to +85°C, exceeding typical MCU internal reset tolerance of ±5%. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| BZX84-C9V1 | Same 9.1 V ±5%, but 15 Ω ZZ at 5 mA (vs. 8.0 Ω at 20 mA); 350 mW PD rating | Higher ZZ reduces regulation precision in high-current shunt regulators; better suited for low-IZ biasing | Select BZX84-C9V1 only if design uses <5 mA Zener current and requires higher power margin |
| MMBZ5239BS | Same electrical specs, but SOD-123 package (larger footprint, 2x thermal mass); identical SOT-23 marking "8P" | Improved thermal dissipation (ψJL = 150°C/W) supports sustained 250 mW operation in high-ambient environments | Choose MMBZ5239BS when board-level thermal management is insufficient for SOT-23's 465°C/W RθJA |
Compared with BZX84-C9V1 and MMBZ5239BS, the MMBZ5239B delivers optimal balance of regulation precision (low ZZ at 20 mA), compact size (SOT-23), and thermal performance for space-constrained 9.1 V reference designs requiring ≤250 mW dissipation.
Availability
MMBZ5239B is available at Aetrix Electronics and suitable for industrial sensor signal conditioning, USB port overvoltage protection, and programmable logic controller input protection requiring stable component supply and consistent parametric performance.
Supply support for MMBZ5239B 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
Fairchild Semiconductor was a leading designer of high-performance analog and discrete semiconductors, acquired by ON Semiconductor in 2016; its legacy Zener diode portfolio remains widely deployed in industrial and consumer systems.
The MMBZ52xxB series was engineered for precision voltage reference and transient suppression in space-constrained, low-power applications-emphasizing tight tolerance, low impedance, and robust thermal behavior in SOT-23 packaging.
FAQ
What is the exact Zener voltage range for MMBZ5239B at 20 mA test current?
The MMBZ5239B has a guaranteed Zener voltage range of 8.645 V to 9.555 V when tested at IZ = 20 mA and TA = 25°C, corresponding to a nominal 9.1 V ±5% tolerance. This range is confirmed in the Absolute Maximum Ratings table and Electrical Characteristics section of the Fairchild Rev. 1.5 datasheet. The MMBZ5239B maintains this specification across its qualified operating temperature range.
Can MMBZ5239B be used as a bidirectional ESD protection device?
Yes, the MMBZ5239B can serve as a bidirectional clamp: its forward voltage is specified at ≤0.9 V at IF = 10 mA, while its reverse Zener action activates at ~9.1 V. This dual-mode behavior makes the MMBZ5239B suitable for protecting 5 V or 3.3 V data lines against both positive and negative transients-provided series current limiting is applied per IEC 61000-4-2 requirements.
What is the maximum power dissipation of MMBZ5239B on a standard FR-4 PCB?
The MMBZ5239B is rated for 250 mW power dissipation when mounted on a standard FR-4 PCB (76.2 mm × 114.3 mm) at TA = 25°C, based on its RθJA of 465°C/W. Derating is required above 25°C ambient: power must be reduced by 0.54 mW/°C above 25°C to maintain TJ ≤ 150°C. This value is explicitly listed in the Absolute Maximum Ratings table for the MMBZ5239B.
Does MMBZ5239B have a no-connect pin, and how should it be handled on the PCB?
Yes, the MMBZ5239B in SOT-23 package has Pin 2 designated as NC (No Connection). It is internally unconnected and must remain electrically floating-no trace, pad, or solder joint should be assigned to Pin 2. PCB layout must isolate this pad from all copper features to prevent unintended coupling or solder bridging, as confirmed in the Connection Diagram of the MMBZ5239B datasheet.
How does the Zener impedance of MMBZ5239B affect voltage regulation accuracy?
The MMBZ5239B exhibits a maximum Zener impedance (ZZ) of 8.0 Ω at IZ = 20 mA. This low value means that a ±1 mA change in Zener current causes only ±8 mV output variation-critical for maintaining regulation accuracy in shunt references feeding op-amp bias networks or ADC reference dividers. This ZZ spec is measured and guaranteed per the Electrical Characteristics table for the MMBZ5239B.
MMBZ5239B Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- TO-236-3, SC-59, SOT-23-3
- Packaging:
- Bulk
- Product Status:
- Active
- Voltage - Zener (Nom) (Vz):
- 9.1 V
- Tolerance:
- ±5%
- Power - Max:
- 300 mW
- Impedance (Max) (Zzt):
- 10 Ohms
- Current - Reverse Leakage @ Vr:
- 3 µA @ 7 V
- Voltage - Forward (Vf) (Max) @ If:
- 900 mV @ 10 mA
- Operating Temperature:
- -
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-23
MMBZ5239B FAQ
1.How can I place an order for MMBZ5239B through Aetrix?
Please submit a Request for Quotation (RFQ) for MMBZ5239B 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 MMBZ5239B reliable?
The price and inventory of MMBZ5239B are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MMBZ5239B is usually 5 days.
3.What payment methods are accepted for MMBZ5239B?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MMBZ5239B transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MMBZ5239B?
MMBZ5239B orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MMBZ5239B 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 MMBZ5239B?
For technical support, including MMBZ5239B datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MMBZ5239B requirements.
6.How does Aetrix verify that MMBZ5239B is sourced from the original manufacturer or authorized distributors?
All MMBZ5239B 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 MMBZ5239B meets industry standards.
7.What is the process for return or replacement of MMBZ5239B?
All MMBZ5239B units undergo pre-shipment inspection (PSI). If there is an issue with MMBZ5239B, 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 MMBZ5239B part is unused and in its original packaging.
Return procedure for MMBZ5239B:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
MMBZ5239B Tags
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