onsemi MMSZ5237BT1

Overview

MMSZ5237BT1 from onsemi is a 5% tolerance, 8.2 V Zener diode in SOD−123 surface-mount package, rated for 500 mW power dissipation at TL = 75°C, with 8 Ω dynamic impedance at 20 mA test current and 3 µA reverse leakage at 6.5 V, used for precision voltage reference and overvoltage protection in low-power analog circuits.

For engineers reviewing the MMSZ5237BT1 datasheet, pinout, applications, or equivalent options, this device serves as a stable shunt regulator in power supply feedback paths, sensor biasing networks, and ESD-protected I/O clamping circuits where thermal equilibrium Zener voltage stability and Class 3 ESD robustness (>16 kV HBM) are required.

Technical Context

The MMSZ5237BT1 operates as a silicon planar Zener diode with junction temperature range −55°C to +150°C and thermal resistance of 340°C/W (junction-to-ambient) on FR−5 board. Its Zener voltage is specified under thermal equilibrium conditions at TL = 30°C ±1°C, ensuring stable regulation across ambient variations.

It exhibits 500 Ω maximum Zener impedance at knee current (IZK = 0.25 mA), 0.95 V forward voltage at 10 mA, and 0.25 µA reverse leakage at VR = 6.5 V - confirming suitability for low-current reference and clamping applications without significant parasitic loading.

Key Specifications

Pinout & Package

SOD−123 plastic surface-mount package with cathode indicated by polarity band; dimensions: 2.54–2.84 mm length × 1.40–1.80 mm width × 0.94–1.35 mm height; RoHS-compliant, Pb-free construction.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BZX84-C8V2, MMSZ5237BT1 offers 67% higher power rating and better thermal performance in smaller area; versus MMSZ5237ET1G, it lacks automotive qualification but provides identical regulation performance at lower cost for commercial-grade designs.

Availability

MMSZ5237BT1 is available at Aetrix Electronics and suitable for industrial sensor biasing, USB port ESD clamping, low-power MCU reset circuits, and optocoupler LED current regulation requiring stable component supply and long-term production continuity.

Supply support for MMSZ5237BT1 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

onsemi (formerly ON Semiconductor) is a global semiconductor supplier specializing in energy-efficient power management, analog, sensor, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The MMSZ52xxxT1G series was designed as a high-reliability, surface-mount Zener voltage regulator family targeting cost-sensitive, space-constrained applications needing stable reference voltages from 2.4 V to 110 V with industry-standard thermal and ESD performance.

FAQ

What is the Zener voltage tolerance for MMSZ5237BT1?

The MMSZ5237BT1 has a ±5% tolerance on its nominal 8.2 V Zener voltage, resulting in a guaranteed range of 7.79 V to 8.61 V at 20 mA test current under thermal equilibrium conditions. This tolerance is confirmed in the "5% TOLERANCE FG ELECTRICAL CHARACTERISTICS" table on page 3 of the official datasheet, and applies specifically to devices marked with the "B" suffix.

Does MMSZ5237BT1 meet automotive qualification standards?

No, MMSZ5237BT1 is not AEC-Q101 qualified. The automotive-grade variant is MMSZ5237ET1G (or SZMMSZ5237BT1G), which carries the "SZ" prefix and is explicitly listed as PPAP-capable and AEC−Q101 qualified in the datasheet's Features section. MMSZ5237BT1 is intended for commercial and industrial applications only.

What is the maximum continuous Zener current for MMSZ5237BT1?

The maximum continuous DC Zener current for MMSZ5237BT1 is approximately 61 mA, calculated from its 500 mW power rating divided by the minimum Zener voltage (8.2 V × 0.95 derating ≈ 7.8 V). However, safe operation requires thermal derating above 75°C ambient - the datasheet specifies 6.7 mW/°C reduction beyond that point to prevent junction overheating.

How does the SOD−123 package of MMSZ5237BT1 compare to DO-35 or SOT-23 in thermal performance?

The SOD−123 package of MMSZ5237BT1 delivers 340°C/W junction-to-ambient thermal resistance on FR-5 board, significantly better than DO-35 (≈500°C/W) and competitive with SOT-23 (≈450°C/W). This enables higher power handling in compact layouts, as confirmed in the "MAXIMUM RATINGS" table where PD = 500 mW is specified specifically for the SOD−123 footprint.

Is MMSZ5237BT1 suitable for use as an ESD protection device on high-speed data lines?

Yes - MMSZ5237BT1 is rated for Class 3 HBM ESD (>16 kV) and exhibits typical capacitance of <5 pF at 50% V_Z, making it suitable for ESD clamping on low-to-medium speed digital lines like USB 2.0 or RS-485. Its fast Zener turn-on and low leakage (3 µA @ 6.5 V) prevent signal integrity degradation while providing robust transient suppression.