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Diodes Incorporated MMBZ5255B-7
- Part No.:
- MMBZ5255B-7
- Manufacturer:
- Diodes Incorporated
- Category:
- Single Zener Diodes
- Package:
- TO-236-3, SC-59, SOT-23-3
- Datasheet:
-
MMBZ5255B-7.pdf
- Description:
- DIODE ZENER 28V 350MW SOT23-3
- Quantity:
- Payment:
- Shipping:
Inventory:2,926
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Product details
Overview
MMBZ5255B-7 from Diodes Incorporated is a 28 V, 4.5 mA nominal Zener diode in SOT23 package, rated for 350 mW power dissipation at 25°C ambient on FR-4 PCB, with 44 Ω dynamic impedance at test current and 0.1 µA reverse leakage at 21 V, used for precision voltage reference and overvoltage clamping in low-power analog circuits.
For engineers reviewing the MMBZ5255B-7 datasheet, MMBZ5255B-7 pinout, MMBZ5255B-7 application, or MMBZ5255B-7 equivalent, key selection criteria include Zener voltage tolerance (±3.6%), thermal resistance (357 °C/W), JEDEC-compliant reliability, RoHS/Green compliance, and SOT23 footprint compatibility with automated assembly.
Technical Context
This Zener diode operates in reverse breakdown mode with a nominal regulation voltage of 28 V at 4.5 mA test current, exhibiting 44 Ω impedance at 1 kHz and maintaining stable regulation down to 0.25 mA knee current (ZZK = 600 Ω). Its planar die construction ensures consistent voltage tolerance and low temperature coefficient.
Designed for surface-mount operation on standard FR-4 PCBs, it delivers 350 mW dissipation only under specified pad layout conditions and derates linearly above 25°C ambient per Figure 1, with maximum junction temperature limited to +150°C and storage range spanning −65°C to +150°C.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 28 V nominal, 26.6–29.4 V range at IZT = 4.5 mA - defines precise clamping threshold for 24 V rail protection |
| Power Dissipation (PD) | 350 mW on FR-4 board - sets maximum continuous clamp energy without heatsinking |
| Zener Impedance (ZZT) | 44 Ω at 1 kHz, IZT = 4.5 mA - determines regulation stiffness under dynamic load transients |
| Reverse Leakage (IR) | 0.1 µA at VR = 21 V - ensures negligible standby current in high-impedance bias networks |
| Thermal Resistance (RθJA) | 357 °C/W - quantifies junction-to-ambient rise per mW, critical for thermal design margin |
| Operating Temperature | −65°C to +150°C - supports industrial and automotive under-hood environments |
Pinout & Package
Package: SOT23 - 3-terminal surface-mount plastic package with matte tin-plated Alloy 42 leadframe, UL 94V-0 rated, 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 |
| Cathode (Pin 2) | Zener breakdown terminal / voltage regulation node | Connected to protected node or reference point requiring 28 V clamping |
| No Connect (Pin 3) | Unused internal die attachment flag | Electrically isolated; must be left floating or tied to cathode per layout best practice |
Key Features
| Feature | Design Value |
|---|---|
| Planar die construction | Enables tight ±3.6% VZ tolerance and repeatable Zener knee characteristics across production lots |
| 350 mW FR-4 power rating | Validated dissipation using Diodes' recommended pad layout - eliminates need for custom thermal relief |
| JEDEC High Reliability qualification | Meets AEC-Q200 stress test requirements for passive components - suitable for automotive ECUs without Q-suffix requalification |
| Halogen- and antimony-free "Green" compound | <900 ppm Br, <900 ppm Cl, <1000 ppm Sb - satisfies strict environmental compliance for export and Tier-1 OEM programs |
Applications
| Industrial Sensor Signal Conditioning | USB-C Power Delivery Clamp |
|---|---|
|
Use Scenario: Stabilizing reference voltage for 24 V industrial pressure transducers operating in −40°C to +85°C ambient. IC Role / Device Role / Timing Role: Zener diode acting as shunt voltage reference and transient suppressor at ADC input stage. Use Value: 28 V clamping prevents overvoltage damage to 3.3 V ADC front-end while maintaining <0.1 µA leakage to preserve sensor bias accuracy. |
Use Scenario: Protecting USB-C CC line receivers from 20 V PD negotiation surges during plug insertion. IC Role / Device Role / Timing Role: Fast-response shunt clamp limiting CC line voltage to ≤28 V during hot-plug events. Use Value: 44 Ω Zener impedance ensures sub-100 ns response to 1 kV/µs transients, meeting USB-IF ESD immunity requirements. |
| Automotive Body Control Module (BCM) | Low-Power IoT Node Voltage Reference |
|
Use Scenario: Providing regulated 28 V supply for LIN bus transceiver bias in BCM modules exposed to load-dump pulses. IC Role / Device Role / Timing Role: Primary overvoltage clamp parallel to 24 V rail, absorbing ISO 7637-2 Pulse 5a energy. Use Value: 350 mW rating sustains 100 ms load-dump events up to 35 V without thermal runaway, validated per AEC-Q200. |
Use Scenario: Generating stable 28 V reference for battery-monitoring ICs in coin-cell-powered asset trackers. IC Role / Device Role / Timing Role: Low-leakage Zener reference enabling <1 µA sleep-mode current in 10-year life designs. Use Value: 0.1 µA reverse leakage at 21 V ensures reference stability without depleting CR2032 capacity over 365-day deployment. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener voltage reference applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| BZX84-C27LT1G | 27 V nominal, ±5% tolerance, 300 mW rating, 70 Ω ZZT | Lower clamping voltage and higher impedance - less precise for 24 V rail monitoring | Select when tighter 28 V regulation is not required and cost is primary constraint |
| MMBZ5256B-7-F | 30 V nominal, ±3.5% tolerance, same SOT23 package and 350 mW rating | Higher clamp threshold - unsuitable for 24 V systems needing headroom below 28 V | Choose only if system requires 30 V overvoltage protection with identical thermal performance |
Compared with BZX84-C27LT1G and MMBZ5256B-7-F, MMBZ5255B-7 provides optimal 28 V regulation with lowest Zener impedance (44 Ω) and tightest voltage tolerance (±3.6%) in its class, making it preferred for precision 24 V rail supervision where clamping accuracy and dynamic response are critical.
Availability
MMBZ5255B-7 is available at Aetrix Electronics and suitable for industrial sensor interfaces, USB-C power delivery protection, and automotive body control modules requiring stable component supply with full traceability and long-term lifecycle support.
Supply support for MMBZ5255B-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 semiconductor company specializing in discrete, analog, and mixed-signal solutions, with manufacturing certified to IATF 16949 and quality systems aligned to AEC-Q standards.
This device belongs to the MMBZ52xxB series of 350 mW surface-mount Zener diodes, designed specifically for high-reliability voltage regulation and transient suppression in space-constrained industrial and automotive PCBs.
FAQ
What is the maximum Zener test current (IZT) for MMBZ5255B-7?
The maximum Zener test current is 4.5 mA, as specified in the Electrical Characteristics table on page 3 of DS18011 Rev. 26-2. This current establishes the 28 V nominal regulation point and is used to measure Zener impedance (44 Ω) and voltage tolerance (±3.6%). Operation beyond this current requires thermal derating per Figure 1.
Is MMBZ5255B-7 qualified for automotive applications?
MMBZ5255B-7 meets JEDEC High Reliability standards referenced in AEC-Q200 and is manufactured in IATF 16949-certified facilities. While it is not an AEC-Q200-qualified part by default, Diodes offers automotive-grade variants with Q-suffix (e.g., MMBZ5255BQ-7-F) that include PPAP documentation and extended testing.
Can MMBZ5255B-7 be used in place of a 27 V Zener like BZX84-C27?
No - MMBZ5255B-7 has a nominal 28 V Zener voltage versus 27 V for BZX84-C27, and its tighter ±3.6% tolerance (26.6–29.4 V) differs from BZX84-C27's ±5% (25.65–28.35 V). Substitution requires verification of system headroom margins and impedance impact on regulation stability.
What is the meaning of the "-7-F" suffix in MMBZ5255B-7-F?
The "-7-F" suffix indicates tape-and-reel packaging: "7" denotes 3,000 units per reel, and "F" signifies Diodes Incorporated's standard green, halogen-free, RoHS-compliant finish. The base part number MMBZ5255B identifies the 28 V Zener variant; the full orderable number is MMBZ5255B-7-F.
MMBZ5255B-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):
- 28 V
- Tolerance:
- ±5%
- Power - Max:
- 350 mW
- Impedance (Max) (Zzt):
- 44 Ohms
- Current - Reverse Leakage @ Vr:
- 100 nA @ 21 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
MMBZ5255B-7 FAQ
1.How can I place an order for MMBZ5255B-7 through Aetrix?
Please submit a Request for Quotation (RFQ) for MMBZ5255B-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 MMBZ5255B-7 reliable?
The price and inventory of MMBZ5255B-7 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MMBZ5255B-7 is usually 5 days.
3.What payment methods are accepted for MMBZ5255B-7?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MMBZ5255B-7 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MMBZ5255B-7?
MMBZ5255B-7 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MMBZ5255B-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 MMBZ5255B-7?
For technical support, including MMBZ5255B-7 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MMBZ5255B-7 requirements.
6.How does Aetrix verify that MMBZ5255B-7 is sourced from the original manufacturer or authorized distributors?
All MMBZ5255B-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 MMBZ5255B-7 meets industry standards.
7.What is the process for return or replacement of MMBZ5255B-7?
All MMBZ5255B-7 units undergo pre-shipment inspection (PSI). If there is an issue with MMBZ5255B-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 MMBZ5255B-7 part is unused and in its original packaging.
Return procedure for MMBZ5255B-7:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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