Diodes Incorporated MMSZ5259BS-7

Overview

MMSZ5259BS-7 from Diodes Incorporated is a surface-mount Zener diode with nominal zener voltage 39 V, ±5% tolerance (37.05–40.95 V), 200 mW power dissipation, 80 Ω zener impedance at 3.2 mA test current, and 0.1 µA reverse leakage at 30 V. It serves as a precision voltage reference or overvoltage clamp in low-power analog signal conditioning and power supply regulation circuits.

For engineers reviewing the MMSZ5259BS-7 datasheet, MMSZ5259BS-7 pinout, MMSZ5259BS-7 application, or MMSZ5259BS-7 equivalent, key selection criteria include its SOD-323 package footprint, thermal resistance of 625 °C/W, cathode-band polarity marking, and compatibility with automated pick-and-place assembly for space-constrained PCBs.

Technical Context

This Zener diode operates in reverse breakdown mode to maintain stable voltage across its terminals under controlled current conditions. Its planar die construction ensures consistent breakdown characteristics and low leakage, while the SOD-323 package enables high-density mounting without compromising thermal performance on FR-4 boards.

The device is characterized at 25 °C with a 3.2 mA test current, delivering 39 V nominal regulation with 80 Ω dynamic impedance and 0.1 µA reverse leakage at VR = 30 V. Power derating begins above 25 °C per the specified curve, reaching zero dissipation at 150 °C ambient.

Key Specifications

Pinout & Package

Package: SOD-323 - ultra-small plastic surface-mount case (2.30–2.70 mm length, 1.20–1.40 mm width, 0.25–0.35 mm thickness), cathode indicated by molded band, lead-free matte tin plating, moisture sensitivity level 1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BZX584-C39 and MMBZ5259ELT1G, MMSZ5259BS-7 offers optimal balance of SOD-323 size, 200 mW rating, and 625 °C/W thermal resistance-making it preferred for space-limited, thermally managed 39 V reference designs.

Availability

MMSZ5259BS-7 is available at Aetrix Electronics and suitable for industrial sensor interfaces, USB-C protection circuits, and low-power IoT node power management requiring stable component supply and full RoHS compliance.

Supply support for MMSZ5259BS-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 and manufacturing operations across Asia and the Americas.

MMSZ5259BS-7 belongs to the MMSZ52xxBS series of general-purpose Zener diodes designed for precision voltage reference and overvoltage protection in consumer, computing, and industrial applications where small size and reliability are critical.

FAQ

What is the maximum reverse voltage (VR) at which MMSZ5259BS-7 guarantees ≤0.1 µA leakage?

The datasheet specifies 0.1 µA maximum reverse leakage current at VR = 30 V. This value is measured under DC conditions at 25 °C ambient and defines the upper limit of off-state conduction before entering breakdown. Operation above 30 V in reverse bias will increase leakage exponentially and must be avoided unless intentional Zener conduction is required.

Can MMSZ5259BS-7 be used in series to achieve higher regulated voltage?

No-MMSZ5259BS-7 is not characterized or guaranteed for series operation. Zener voltage tolerances (±5%) and mismatched temperature coefficients cause uneven voltage division and potential thermal runaway. For higher voltages, use a single Zener rated for that voltage or a dedicated programmable shunt regulator IC.

Is the SOD-323 package compatible with reflow profiles for lead-free soldering?

Yes-the device is qualified for lead-free reflow per J-STD-020D Level 1 moisture sensitivity, with peak temperatures up to 260 °C. The matte tin finish over Alloy 42 leadframe ensures reliable wetting and intermetallic formation. Recommended profile follows IPC/JEDEC J-STD-020D with ramp rate ≤3 °C/s and time above liquidus 60–150 s.

Does MMSZ5259BS-7 have a specified zener voltage temperature coefficient?

No explicit temperature coefficient (TC) is published in DS31038 Rev. 13. However, typical behavior for 39 V Zeners in this series shows positive TC (~+0.07 %/°C), meaning VZ increases slightly with temperature. For precision references, system-level calibration or TC-compensated designs are recommended.