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Diodes Incorporated MMBZ5251B-7
- Part No.:
- MMBZ5251B-7
- Manufacturer:
- Diodes Incorporated
- Category:
- Single Zener Diodes
- Package:
- TO-236-3, SC-59, SOT-23-3
- Datasheet:
-
MMBZ5251B-7.pdf
- Description:
- DIODE ZENER 22V 350MW SOT23-3
- Quantity:
- Payment:
- Shipping:
Inventory:2,042
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Product details
Overview
MMBZ5251B-7 from Diodes Incorporated is a 22V, 350mW surface-mount Zener diode in SOT23 package, with nominal Zener voltage 22V (20.9–23.1V), test current 5.6mA, dynamic impedance 29Ω at 1kHz, and reverse leakage ≤0.1µA at 17V, used for precision voltage regulation and overvoltage protection in low-power analog circuits.
For engineers reviewing the MMBZ5251B-7 datasheet, MMBZ5251B-7 pinout, MMBZ5251B-7 application, or MMBZ5251B-7 equivalent, key selection criteria include Zener voltage tolerance, impedance at operating current, power derating above +25°C, and compatibility with automated SMT assembly on FR-4 PCBs.
Technical Context
This Zener diode operates in reverse breakdown mode with tightly controlled voltage regulation across its specified test current range. Its planar die construction ensures stable Zener characteristics and low temperature coefficient over -65°C to +150°C operating range.
Thermal resistance is 357°C/W when mounted on FR-4 PCB with recommended pad layout, requiring derating above +25°C per Figure 1. It exhibits low reverse leakage (<0.1µA at VR = 17V) and maintains impedance below 29Ω at IZT = 5.6mA and f = 1kHz.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (Nom) | 22 V - Stable reference voltage at 5.6 mA test current, ±5% tolerance (20.9–23.1 V). |
| Power Dissipation | 350 mW - Maximum continuous power on FR-4 board; requires linear derating above +25°C ambient. |
| Zener Impedance | 29 Ω - Dynamic resistance at 5.6 mA and 1 kHz; determines regulation stiffness under load variation. |
| Reverse Leakage | ≤0.1 µA at 17 V - Ensures minimal quiescent current in standby protection circuits. |
| Forward Voltage | 0.9 V at 10 mA - Enables use as clamp or level-shifter in bidirectional signal paths. |
| Thermal Resistance | 357 °C/W - Defines junction-to-ambient temperature rise per watt; critical for thermal design margin. |
Pinout & Package
Package: SOT23 - 3-terminal surface-mount plastic package, 2.9 mm × 1.3 mm × 1.0 mm, matte tin-plated alloy 42 leadframe, moisture sensitivity level 1.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode (Pin 1) | Forward conduction terminal / cathode reference ground | Connected to circuit ground or lower potential node during Zener operation; defines polarity for reverse-bias regulation. |
| Cathode (Pin 2) | Zener regulation output / voltage reference node | Provides stable 22 V reference when reverse-biased; connects to supply rail or protected node. |
| No Connect (Pin 3) | Internal die attach flag / mechanical support | Not electrically connected; serves structural role in SOT23 molding; must remain floating or grounded per layout guidelines. |
Key Features
| Feature | Design Value |
|---|---|
| Planar die construction | Ensures repeatable Zener voltage distribution and long-term stability under thermal cycling. |
| 350 mW dissipation on FR-4 | Validated power handling without heatsink; supports compact PCB layouts in space-constrained designs. |
| Lead-free & RoHS 3 compliant | Fully compliant with EU Directive 2015/863/EU; suitable for global commercial and industrial shipments. |
| Halogen- and antimony-free | Meets "Green" definition (<900 ppm Br, <900 ppm Cl, <1000 ppm Sb); supports eco-design requirements. |
Applications
| Industrial Sensor Signal Conditioning | USB Port Overvoltage Protection |
|---|---|
|
Use Scenario: Stabilizing reference voltage for 12-bit ADC front-end in temperature/humidity transmitters. IC Role / Device Role / Timing Role: Zener reference source for op-amp biasing and ADC VREF input. Use Value: 22 V Zener clamps transient surges while maintaining ±0.5% regulation error at 5.6 mA, enabling <±1 LSB measurement accuracy. |
Use Scenario: Protecting 5 V USB data lines from ESD and accidental 12 V misconnection. IC Role / Device Role / Timing Role: Bidirectional transient voltage suppressor (TVS-like function) using forward and reverse conduction. Use Value: 0.9 V forward drop limits low-side clamp voltage; 22 V reverse standoff prevents false triggering during normal 5 V operation. |
| Low-Power IoT Node Power Management | Automotive Body Control Module (BCM) Backup Regulator |
|
Use Scenario: Providing regulated 22 V bias for RF power amplifier in battery-powered LPWAN sensor nodes. IC Role / Device Role / Timing Role: Primary voltage reference for discrete LDO pre-regulator stage. Use Value: 29 Ω Zener impedance ensures <15 mV output variation across 1–5 mA load swing, extending battery life via efficient dropout control. |
Use Scenario: Maintaining microcontroller reset threshold during cold-crank battery dip (down to 6 V). IC Role / Device Role / Timing Role: Standby voltage supervisor feeding RC reset circuit with hysteresis. Use Value: ≤0.1 µA leakage at 17 V minimizes parasitic drain on backup capacitor, sustaining >10 s hold-up time. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| BZX84-C22LT1G | Same 22 V nominal Zener, but 225 mW rating and 40 Ω Zz at 5 mA; SOT23 package with identical pinout. | Limited to lower-power regulation; unsuitable where full 350 mW dissipation or tighter impedance is required. | Select when cost sensitivity outweighs power margin needs and thermal derating is acceptable. |
| MMBZ5251BS-7-F | Same electrical specs, but automotive-grade (AEC-Q101 qualified), with PPAP support and IATF 16949 manufacturing. | Required for automotive BCM, ADAS sensors, or any application needing change-controlled qualification. | Choose for automotive deployments; otherwise, standard MMBZ5251B-7 offers identical performance at lower cost. |
Compared with BZX84-C22LT1G, MMBZ5251B-7 delivers 55% higher power headroom and 27% lower impedance for improved regulation fidelity; versus MMBZ5251BS-7-F, it provides identical electrical behavior without automotive qualification overhead.
Availability
MMBZ5251B-7 is available at Aetrix Electronics and suitable for industrial sensor conditioning, USB port protection, and low-power IoT node power management requiring stable component supply and SMT-compatible packaging.
Supply support for MMBZ5251B-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 manufacturer of discrete semiconductors and analog ICs, headquartered in Plano, Texas, with design, manufacturing, and sales operations across Asia, Europe, and the Americas.
The MMBZ52xxB series belongs to Diodes' precision Zener diode product line, engineered for high-stability voltage reference and protection in commercial and industrial applications where tight tolerance and low leakage are critical.
FAQ
What is the maximum reverse voltage this Zener can withstand before breakdown?
The MMBZ5251B-7 has a nominal Zener voltage of 22 V with a guaranteed range of 20.9–23.1 V at 5.6 mA. Breakdown occurs within this band; operation above 23.1 V risks exceeding power limits unless current is strictly limited by external series resistance. The device is not rated for sustained operation beyond its specified Zener voltage range.
Can this part be used in place of a TVS diode for ESD protection?
While MMBZ5251B-7 offers low leakage and sharp knee characteristics, it is not characterized or qualified as an ESD protection device. Its 350 mW power rating and 29 Ω impedance are optimized for regulation-not transient suppression. For IEC 61000-4-2 compliance, dedicated TVS diodes like PESD5V0S1BA are recommended instead.
Is the SOT23 pinout standardized across Diodes' Zener families?
Yes-MMBZ52xxB devices follow JEDEC-standard SOT23 pinout: Pin 1 = Anode, Pin 2 = Cathode, Pin 3 = NC (non-connected flag). This matches BZX84, BZT52, and other Diodes SOT23 Zeners, enabling direct layout reuse and footprint compatibility across voltage grades.
How does thermal derating affect usable power at 85°C ambient?
At +85°C ambient, the MMBZ5251B-7's usable power drops to 245 mW, calculated as 350 mW × (1 − (85 − 25)/150), per Figure 1 derating curve. This assumes FR-4 mounting with recommended pad layout; inadequate copper area further reduces safe operating power.
MMBZ5251B-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):
- 22 V
- Tolerance:
- ±5%
- Power - Max:
- 350 mW
- Impedance (Max) (Zzt):
- 29 Ohms
- Current - Reverse Leakage @ Vr:
- 100 nA @ 17 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
MMBZ5251B-7 FAQ
1.How can I place an order for MMBZ5251B-7 through Aetrix?
Please submit a Request for Quotation (RFQ) for MMBZ5251B-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 MMBZ5251B-7 reliable?
The price and inventory of MMBZ5251B-7 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MMBZ5251B-7 is usually 5 days.
3.What payment methods are accepted for MMBZ5251B-7?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MMBZ5251B-7 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MMBZ5251B-7?
MMBZ5251B-7 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MMBZ5251B-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 MMBZ5251B-7?
For technical support, including MMBZ5251B-7 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MMBZ5251B-7 requirements.
6.How does Aetrix verify that MMBZ5251B-7 is sourced from the original manufacturer or authorized distributors?
All MMBZ5251B-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 MMBZ5251B-7 meets industry standards.
7.What is the process for return or replacement of MMBZ5251B-7?
All MMBZ5251B-7 units undergo pre-shipment inspection (PSI). If there is an issue with MMBZ5251B-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 MMBZ5251B-7 part is unused and in its original packaging.
Return procedure for MMBZ5251B-7:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
MMBZ5251B-7 Tags
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