Diodes Incorporated MMBZ5257BS-7-F

Overview

MMBZ5257BS-7-F from Diodes Incorporated is a dual isolated 33 V, 3.8 mA Zener diode in SOT-363 package, rated for 200 mW power dissipation and 625 °C/W thermal resistance, with 58 Ω zener impedance at 1 kHz and 0.1 μA reverse leakage at 25 V, used for precision voltage reference and overvoltage clamping in space-constrained analog signal conditioning circuits.

For engineers reviewing the MMBZ5257BS-7-F datasheet, MMBZ5257BS-7-F pinout, MMBZ5257BS-7-F application, or MMBZ5257BS-7-F equivalent, key selection criteria include nominal zener voltage tolerance (±3.5%), low leakage at rated VR, dual-diode isolation for bidirectional protection, and SOT-363 footprint compatibility with high-density PCB layouts.

Technical Context

This dual-Zener device integrates two electrically isolated 33 V zener junctions in a single SOT-363 package, enabling symmetrical clamping or independent reference generation without cross-talk. Each diode operates with a test current of 3.8 mA and exhibits 700 Ω maximum knee impedance at 0.25 mA.

The device complies with J-STD-020D Level 1 moisture sensitivity and UL 94V-0 flammability rating, and uses matte tin-plated Alloy 42 leads for lead-free soldering. Its thermal derating curve specifies linear power reduction above 25 °C ambient, reaching zero dissipation at 150 °C.

Key Specifications

Pinout & Package

SOT-363 surface-mount package with six terminals: two anodes (A1, A2), two cathodes (C1, C2), and two no-connect (NC) pins. Molded plastic case meets UL 94V-0; polarity defined by top-view schematic showing C1–A1–C2–A2–NC–NC sequence.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-Zener voltage reference applications.

Compared with BZX84-C33LT1G and PDZ33B,115, MMBZ5257BS-7-F uniquely delivers dual isolated 33 V references in minimal area, enabling true differential clamping and eliminating inter-diode thermal coupling-critical for precision analog and multi-rail protection where layout space and channel independence are constrained.

Availability

MMBZ5257BS-7-F is available at Aetrix Electronics and suitable for industrial sensor interfaces, USB port protection, low-power battery monitoring, and automotive LIN bus nodes requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MMBZ5257BS-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 semiconductor company specializing in discrete, analog, and mixed-signal ICs, with design centers in Asia, Europe, and the US, serving industrial, computing, consumer, and communications markets.

The MMBZ52xxBS series belongs to Diodes' precision Zener diode product line, engineered for high-reliability voltage reference and transient suppression in compact, automated-assembly-ready packages targeting space-constrained portable and automotive electronics.

FAQ

What is the maximum reverse voltage before breakdown for MMBZ5257BS-7-F?

The nominal zener voltage is 33 V with a guaranteed range of 31.35 V to 34.65 V at 3.8 mA test current. Breakdown occurs within this band; operation below 31.35 V maintains <0.1 μA leakage at 25 V, confirming stable non-conducting behavior in normal bias conditions.

Can MMBZ5257BS-7-F be used for bidirectional ESD protection?

Yes-its dual isolated structure allows one zener (C1/A1) to clamp positive transients and the other (C2/A2) to clamp negative transients independently. With typical capacitance of ~15 pF and 33 V standoff, it meets IEC 61000-4-2 Level 4 for data-line protection without signal distortion.

How does the SOT-363 package affect thermal performance?

The SOT-363 package has a junction-to-ambient thermal resistance of 625 °C/W on FR4 with recommended pad layout. This requires strict adherence to Diodes Inc.'s AP02001 pad dimensions to avoid exceeding 150 °C junction temperature at full 200 mW dissipation in still air.

Is MMBZ5257BS-7-F suitable for automotive applications?

Yes-it operates from −65 °C to +150 °C and meets AEC-Q200 stress-test requirements for passive components when qualified per Diodes Inc.'s automotive-grade variants. The standard MMBZ5257BS-7-F is widely deployed in LIN bus nodes and body-control modules where temperature and reliability are critical.