Diodes Incorporated MMBZ5231BT-7-F

Overview

MMBZ5231BT-7-F from Diodes Incorporated is a 5.1 V, 150 mW surface-mount Zener diode in SOT-523 package, rated for 20 mA test current, 17 Ω dynamic impedance at 20 mA, and 5 µA reverse leakage at 2.0 V, used for precision voltage regulation and overvoltage protection in low-power analog sensor interfaces and microcontroller I/O rail clamping.

For engineers reviewing the MMBZ5231BT-7-F datasheet, MMBZ5231BT-7-F pinout, MMBZ5231BT-7-F application, or MMBZ5231BT-7-F equivalent, key selection criteria include nominal Zener voltage tolerance (±5%), thermal resistance (833 °C/W), low-capacitance clamping behavior (<30 pF), and RoHS-compliant matte tin plating on Alloy 42 leadframe.

Technical Context

This Zener diode employs planar die construction for stable breakdown characteristics and low leakage across -65°C to +150°C operating range. Its ultra-small SOT-523 footprint supports high-density PCB layouts while maintaining 150 mW power dissipation under defined FR-4 pad layout conditions.

Designed for general-purpose voltage reference and transient suppression, it delivers tight 4.85–5.36 V Zener voltage window at 20 mA, with 17 Ω impedance at test current and <5 µA IR at VR = 2.0 V - enabling predictable clamping in 3.3 V and 5 V logic domains.

Key Specifications

Pinout & Package

Package: SOT-523 - ultra-compact plastic-molded case (UL 94V-0), 0.002 g weight, moisture sensitivity level 1, lead-free matte tin plating over Alloy 42 leadframe.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar Zener diode applications.

Compared with BZX584C5V1LT1G and MMBZ5231BS-7-F, the MMBZ5231BT-7-F offers superior low-current regulation (17 Ω vs. 100 Ω) and tighter thermal resistance control (833 °C/W vs. ~1000 °C/W), making it preferred for precision analog sensing and space-constrained 3.3 V system designs.

Availability

MMBZ5231BT-7-F is available at Aetrix Electronics and suitable for industrial sensor conditioning, microcontroller I/O protection, and low-power battery monitoring requiring stable component supply and consistent Zener voltage performance across production lots.

Supply support for MMBZ5231BT-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 centers across Asia and manufacturing facilities in China, Taiwan, and the U.S.

This device belongs to the MMBZ52xxBT series of general-purpose Zener diodes, engineered for automated SMT assembly, low-profile board integration, and reliable voltage reference/clamping in cost-sensitive consumer and industrial electronics.

FAQ

What is the maximum reverse voltage this Zener can withstand before breakdown?

The MMBZ5231BT-7-F has a nominal Zener voltage of 5.1 V with a guaranteed range of 4.85 V to 5.36 V at 20 mA test current. It begins controlled breakdown at the lower end of this range and maintains regulation up to its 150 mW power limit. The absolute maximum non-repetitive peak reverse voltage is not specified beyond the Zener range, and operation above 5.36 V risks exceeding thermal limits.

Can this part be used in place of a 5 V linear regulator for powering small loads?

No - the MMBZ5231BT-7-F is a shunt regulator, not a series regulator. It requires a current-limiting resistor and cannot source significant load current. It is intended for voltage reference, clamping, or low-current biasing (≤20 mA), not for powering downstream circuitry. For active regulation, use a dedicated LDO such as AP2112K-5.0.

Does this Zener diode have polarity markings on the SOT-523 package?

Yes - the cathode is marked with a single band on the SOT-523 package body. Per Diodes Incorporated documentation, the marking code "KE1" appears adjacent to the cathode band. The anode is unmarked, and orientation must follow the top-view schematic in DS30267 Rev. 11-2, where the banded end is cathode.

Is thermal derating required for operation above 25°C ambient?

Yes - the device's 150 mW power rating applies only at TA = 25°C. Above that, power must be linearly derated at 180 µW/°C (150 mW ÷ 833 °C/W), per the Fig. 1 derating curve. At 85°C ambient, maximum allowable dissipation drops to approximately 42 mW, requiring reduced bias current or larger copper pour to maintain safe junction temperature.