Diodes Incorporated MMBZ5251BS-7-F

Overview

MMBZ5251BS-7-F from Diodes Incorporated is a dual isolated 22 V Zener diode pair in SOT-363 package, rated for 200 mW total power dissipation, with nominal zener voltage 22 V (min 20.9 V, max 23.1 V) at 5.6 mA test current, 29 Ω zener impedance at 5.6 mA, and ≤0.1 μA reverse leakage at 17 V, used for precision voltage reference and overvoltage clamping in space-constrained analog signal conditioning circuits.

For engineers reviewing the MMBZ5251BS-7-F datasheet, MMBZ5251BS-7-F pinout, MMBZ5251BS-7-F application, or MMBZ5251BS-7-F equivalent, key selection criteria include dual-zener isolation integrity, low-leakage operation below 17 V reverse bias, thermal derating compliance on FR4 PCBs, and compatibility with automated SMT placement for high-reliability sensor front-ends and power rail supervisors.

Technical Context

This device integrates two electrically isolated Zener diodes in a single ultra-small SOT-363 package, enabling bidirectional voltage clamping or dual-rail reference generation without cross-coupling. Each diode operates independently with specified zener voltage tolerance (±5%), dynamic impedance, and leakage behavior under defined test conditions.

It employs planar die construction for stable breakdown characteristics and is qualified for lead-free reflow per J-STD-020D Level 1 moisture sensitivity. Thermal resistance junction-to-ambient is 625 °C/W when mounted on FR4 with recommended pad layout, limiting continuous power to 200 mW at 25 °C ambient.

Key Specifications

Pinout & Package

SOT-363 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 flammability rating; terminals are matte tin-plated for solderability.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BZX84-C22LT1G and MMBZ5251B-7-F, MMBZ5251BS-7-F uniquely delivers two isolated 22 V Zeners in one SOT-363, reducing component count and interconnect parasitics in compact dual-supply monitoring systems.

Availability

MMBZ5251BS-7-F is available at Aetrix Electronics and suitable for industrial sensor interfaces, portable medical wearables, USB-C port supervision, and low-power microcontroller I/O protection requiring stable component supply across extended production cycles.

Supply support for MMBZ5251BS-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, specializing in high-reliability components for industrial, computing, and consumer markets with ISO/TS 16949-certified operations.

The MMBZ52xxBS series belongs to Diodes' precision Zener diode product line, engineered specifically for space-constrained voltage regulation and bidirectional ESD protection in automated SMT environments.

FAQ

What is the maximum reverse voltage that can be continuously applied across either Zener element?

The absolute maximum reverse voltage is 17 V, as specified by the maximum reverse leakage test condition (I_R ≤ 0.1 μA at V_R = 17 V). Exceeding this voltage risks increased leakage and potential thermal runaway under sustained bias, especially above 70 °C ambient.

How does the dual-isolation architecture affect PCB layout requirements?

Each Zener pair (C1/A1 and C2/A2) must be routed with full galvanic separation-no shared traces, vias, or copper pours between channels. The NC pins must remain unconnected and surrounded by clearance to avoid unintended coupling or solder bridging during reflow.

Can MMBZ5251BS-7-F be used for bidirectional TVS-like transient suppression?

No-it is not rated or characterized for high-energy surge events. Its 200 mW power limit and lack of specified peak pulse ratings mean it functions only as a precision voltage clamp or reference, not as a robust transient voltage suppressor. Use dedicated TVS arrays for surge protection.

Is thermal derating required when operating on 2-layer versus 4-layer PCBs?

Yes. The 625 °C/W R_θJA value assumes the recommended FR4 pad layout on a 2-layer board. On 4-layer boards with internal ground/power planes, thermal resistance improves significantly-typically to ~350–450 °C/W-allowing higher sustained power before derating becomes necessary.