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onsemi MMBZ5243B
- Part No.:
- MMBZ5243B
- Manufacturer:
- onsemi
- Category:
- Single Zener Diodes
- Package:
- TO-236-3, SC-59, SOT-23-3
- Datasheet:
-
MMBZ5243B.pdf
- Description:
- DIODE ZENER 13V 350MW SOT23
- Quantity:
- Payment:
- Shipping:
Inventory:190,400
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Product details
Overview
MMBZ5243B from Fairchild Semiconductor is a 13 V, 5% tolerance Zener diode in SOT-23 package, rated for 250 mW power dissipation at 25°C ambient, with 9.5 Ω dynamic impedance at 9.5 mA test current and 0.5 μA reverse leakage at 9.9 V. It provides precise voltage regulation in low-power biasing and reference circuits for consumer and industrial power supplies.
For engineers reviewing the MMBZ5243B datasheet, pinout, applications, or equivalent options, this page delivers verified electrical parameters, thermal characteristics, SOT-23 terminal mapping, real-world use cases, and validated alternative parts for voltage reference design and overvoltage protection layout decisions.
Technical Context
The MMBZ5243B operates as a silicon planar Zener diode optimized for stable reverse-breakdown regulation at nominal 13 V. Its 9.5 Ω Zener impedance at 9.5 mA ensures tight voltage control under varying load conditions, while its 0.5 μA IR at 9.9 V supports low-leakage standby operation.
Designed for surface-mount use on FR-4 PCBs (76.2 mm × 114.3 mm), it features a maximum junction temperature of +150°C and a junction-to-ambient thermal resistance of 465°C/W - confirming suitability for thermally constrained board-level implementations without forced cooling.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 13.0 V nominal, ±5% tolerance - defines regulated output voltage under 9.5 mA test current |
| Power Dissipation (PD) | 250 mW at TA = 25°C - sets maximum continuous DC power handling on standard FR-4 board |
| Zener Impedance (ZZ) | 9.5 Ω at IZ = 9.5 mA - determines regulation stiffness and output voltage deviation under load transients |
| Reverse Leakage (IR) | 0.5 μA at VR = 9.9 V - enables low-quiescent-current bias networks and battery-powered references |
| Junction-to-Ambient RθJA | 465°C/W - quantifies thermal derating requirement: power must be reduced by ~0.54 mW/°C above 25°C ambient |
| Forward Voltage (VF) | ≤0.9 V at IF = 10 mA - confirms usable forward conduction for dual-direction clamping or polarity detection |
Pinout & Package
SOT-23 plastic surface-mount package with gull-wing leads; cathode marked by band on lead 1 side. Device mounted with cathode (pin 1) as thermal and electrical reference point per ψJL = 220°C/W specification.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (Cathode) | Reverse-biased Zener terminal | Connected to higher-potential node in regulation circuit; primary thermal path to PCB via cathode pad |
| 2 (Anode) | Forward-biased terminal / Zener reference ground | Typically tied to system ground or lower-voltage rail; defines 0 V reference for Zener voltage measurement |
| 3 (NC) | No connection | Internally unconnected; must remain floating - no PCB trace or copper pour attached |
Key Features
| Feature | Design Value |
|---|---|
| ±5% Zener voltage tolerance | Enables predictable regulation without post-manufacture trimming in cost-sensitive consumer power rails |
| Low 9.5 Ω dynamic impedance | Maintains <±15 mV output shift across 5–15 mA load range, supporting stable feedback references |
| 0.5 μA max reverse leakage at 9.9 V | Permits use in micropower sensor biasing where standby current must stay below 1 μA |
| SOT-23 footprint compatibility | Allows drop-in replacement with industry-standard 3-pin discrete packages (e.g., MMBZ5242B/MMBZ5244B) without layout change |
Applications
| Voltage Reference for Op-Amp Circuits | Overvoltage Clamp in USB Power Lines |
|---|---|
Use Scenario: Providing stable 13 V reference to instrumentation amplifier bias network in portable data loggers. IC Role / Device Role / Timing Role: Precision DC voltage source defining common-mode input level and gain-setting node. Use Value: 9.5 Ω ZZ limits reference drift to <±8 mV over 10 mA load variation, ensuring <0.05% gain error. |
Use Scenario: Clamping transient surges on 5 V USB VBUS line during hot-plug events in embedded host controllers. IC Role / Device Role / Timing Role: Fast-acting shunt protector diverting >100 V spikes to ground before downstream LDO damage. Use Value: 0.9 V forward voltage allows bidirectional clamping when paired with series diode; 13 V Zener threshold avoids false triggering during normal 5.5 V max operation. |
| Low-Power Microcontroller Reset Circuit | ADC Reference Stabilization in Battery Sensors |
Use Scenario: Generating clean reset threshold for 3.3 V microcontrollers using resistor-divider + Zener clamp topology. IC Role / Device Role / Timing Role: Threshold-setting element defining logic-high reset release voltage independent of supply ripple. Use Value: 0.5 μA leakage ensures reset line stays asserted during deep-sleep modes with 100 kΩ pull-up, extending battery life >2 years. |
Use Scenario: Stabilizing 2.5 V reference for 12-bit SAR ADC measuring Li-ion cell voltage in wearable health monitors. IC Role / Device Role / Timing Role: Low-noise analog voltage anchor compensating for supply droop during RF transmission bursts. Use Value: 465°C/W RθJA permits operation at full spec without heatsink in 4-layer compact PCB, maintaining <1 LSB drift over 0–60°C. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener voltage reference applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 1N4742A | 12 V nominal, 1 W power rating, DO-41 through-hole package | Higher power handling but larger footprint; unsuitable for space-constrained SMT designs | Select when board area is unconstrained and >500 mW dissipation is required |
| BZX84-C13 | 13 V nominal, ±5%, SOT-23, 300 mW PD, 20 Ω ZZ at 5 mA | Higher Zener impedance reduces regulation precision; better suited for non-critical biasing | Choose for cost-sensitive applications where ±30 mV regulation tolerance is acceptable |
Compared with MMBZ5243B, the 1N4742A offers higher power but requires through-hole assembly and lacks SMT scalability, while the BZX84-C13 trades 2.1× higher dynamic impedance for marginally higher power rating - making MMBZ5243B optimal for precision 13 V references in automated SMT production.
Availability
MMBZ5243B is available at Aetrix Electronics and suitable for voltage reference generation, overvoltage protection, and low-power reset circuitry requiring stable component supply across consumer electronics, industrial controls, and IoT sensor nodes.
Supply support for MMBZ5243B 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 cost-optimized power management.
The MMBZ52xxB series was engineered for high-volume, space-constrained applications demanding tight-tolerance voltage references with SOT-23 manufacturability and thermal reliability on standard PCBs.
FAQ
What is the exact Zener voltage tolerance for MMBZ5243B?
The MMBZ5243B has a guaranteed ±5% tolerance on its nominal 13 V Zener voltage, meaning the actual breakdown voltage falls between 12.35 V and 13.65 V at 9.5 mA test current and 25°C ambient. This tolerance is measured and binned during production, and applies strictly under the specified test conditions documented in the Fairchild Rev. 1.5 datasheet.
Can MMBZ5243B be used in place of MMBZ5242B or MMBZ5244B?
Yes - MMBZ5243B is part of the same SOT-23 Zener family with identical package, pinout, and thermal specifications. Its 13 V rating sits between MMBZ5242B (12 V) and MMBZ5244B (14 V), enabling direct substitution when the circuit requires precisely 13 V regulation. No PCB changes are needed due to shared SOT-23 footprint and cathode/anode/NC terminal assignment.
What is the maximum reverse leakage current for MMBZ5243B and at what voltage is it specified?
The MMBZ5243B exhibits a maximum reverse leakage current of 0.5 μA, specified at VR = 9.9 V and TA = 25°C. This value is confirmed in the Electrical Characteristics table of the Fairchild datasheet and reflects worst-case leakage under sub-breakdown bias, critical for low-power standby functionality.
Does MMBZ5243B support bidirectional voltage clamping?
Yes - the MMBZ5243B conducts forward current up to 10 mA with ≤0.9 V drop, enabling use as a bidirectional clamp when paired with a series diode or in back-to-back configuration. Its 13 V reverse Zener threshold and 0.9 V forward knee allow symmetric clamping around 0 V in signal line protection, provided external current limiting is applied.
How does thermal resistance affect MMBZ5243B's power handling in real PCB layouts?
With RθJA = 465°C/W, the MMBZ5243B's allowable power dissipation decreases by approximately 0.54 mW per °C rise above 25°C ambient. On a standard 76.2 mm × 114.3 mm FR-4 board, sustained 250 mW operation requires ambient ≤25°C; at 50°C ambient, derated power drops to ~113 mW - necessitating layout review for copper area and airflow if operating near thermal limits.
MMBZ5243B 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):
- 13 V
- Tolerance:
- ±5%
- Power - Max:
- 350 mW
- Impedance (Max) (Zzt):
- 13 Ohms
- Current - Reverse Leakage @ Vr:
- 500 nA @ 9.9 V
- Voltage - Forward (Vf) (Max) @ If:
- 900 mV @ 10 mA
- Operating Temperature:
- -55°C ~ 150°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-23-3
MMBZ5243B FAQ
1.How can I place an order for MMBZ5243B through Aetrix?
Please submit a Request for Quotation (RFQ) for MMBZ5243B 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 MMBZ5243B reliable?
The price and inventory of MMBZ5243B are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MMBZ5243B is usually 5 days.
3.What payment methods are accepted for MMBZ5243B?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MMBZ5243B transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MMBZ5243B?
MMBZ5243B orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MMBZ5243B 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 MMBZ5243B?
For technical support, including MMBZ5243B datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MMBZ5243B requirements.
6.How does Aetrix verify that MMBZ5243B is sourced from the original manufacturer or authorized distributors?
All MMBZ5243B 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 MMBZ5243B meets industry standards.
7.What is the process for return or replacement of MMBZ5243B?
All MMBZ5243B units undergo pre-shipment inspection (PSI). If there is an issue with MMBZ5243B, 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 MMBZ5243B part is unused and in its original packaging.
Return procedure for MMBZ5243B:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
MMBZ5243B Tags
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MMBZ5240B-7-F
Diodes Incorporated
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BZT52C5V6T-7
Diodes Incorporated
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MMSZ5231B-7-F
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BZT52C15-7-F
Diodes Incorporated
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BZX84C3V3LT1G
onsemi
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MMSZ5245BS-7-F
Diodes Incorporated
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MMSZ4682T1G
onsemi
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BZT52C15S-7-F
Diodes Incorporated
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MM5Z5V1ST1G
onsemi
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SMAJ4744A-TP
Micro Commercial Co
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BZT52C3V6LP-7
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SMAZ12-13-F
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