Diodes Incorporated 1SMB5937B-13

Overview

1SMB5937B-13 from Diodes Incorporated is a 3.0W surface-mount power Zener diode with a nominal zener voltage of 33V (±5%), 11.4Ω dynamic impedance at 33mA test current, 800Ω maximum knee impedance, and 25.1V minimum zener voltage at 1mA. It provides ESD protection rated Class 3 (>16kV HBM) and operates across –65°C to +150°C in SMB package.

For engineers reviewing the 1SMB5937B-13 datasheet, 1SMB5937B-13 pinout, 1SMB5937B-13 application, or 1SMB5937B-13 equivalent, this device serves as a precision voltage reference and overvoltage clamp in DC power rails, analog sensor conditioning circuits, and industrial control I/O protection where stable 33V regulation and robust transient immunity are required.

Technical Context

This Zener diode operates in reverse breakdown mode to maintain a stable reference voltage under varying load and temperature conditions. Its 33V nominal zener voltage is specified at 33mA test current, with a typical temperature coefficient of +32 mV/°C near this voltage level.

The device delivers 3.0W power dissipation at TL = +75°C with thermal resistance junction-to-terminal of 25°C/W, and derates linearly above that temperature. Its low 0.25µA maximum reverse leakage at 25.1V ensures minimal standby current in voltage-clamp configurations.

Key Specifications

Pinout & Package

Package: SMB (Surface Mount Bandolier), molded plastic case with UL 94V-0 flammability rating, cathode band marking, and matte tin-plated copper alloy leadframe. Dimensions: 3.30–3.94mm (L) × 4.06–4.57mm (W) × 1.96–2.21mm (H).

Key Features

Applications

Equivalent & Alternatives

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

Compared with 1N5937B and SMBJ33A, the 1SMB5937B-13 uniquely combines surface-mount manufacturability, precise 33V DC regulation, and integrated ESD robustness-making it optimal for space-constrained, high-reliability DC power monitoring and clamping applications.

Availability

1SMB5937B-13 is available at Aetrix Electronics and suitable for industrial PLC analog input protection, automotive BCM power rail clamp, and telecom power supply overvoltage protection requiring stable component supply and consistent parametric performance across production batches.

Supply support for 1SMB5937B-13 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, automotive, and computing markets.

The SMB Zener series targets cost-sensitive, high-volume applications demanding robust voltage regulation in compact surface-mount packages-designed specifically for automated manufacturing and harsh-environment reliability.

FAQ

What is the maximum continuous power dissipation for 1SMB5937B-13 at +25°C ambient?

At +25°C ambient temperature, the maximum continuous power dissipation is 550mW, derating linearly by 4.4mW/°C above that temperature. This limit assumes mounting on an FR-4 PCB with Diodes Inc.'s recommended pad layout (AP02001), not the 3.0W rating which applies only at terminal temperature of +75°C.

Does 1SMB5937B-13 support bidirectional transient suppression?

No. The 1SMB5937B-13 is a unidirectional Zener diode optimized for reverse-bias voltage regulation and clamping. It conducts only when reverse voltage exceeds ~33V; forward conduction occurs at ~1.5V but is not designed for bidirectional surge handling like TVS diodes.

How does the temperature coefficient affect regulation accuracy over –40°C to +85°C?

With a typical temperature coefficient of +32mV/°C near 33V, the zener voltage increases by approximately 4V across a 125°C range. At +85°C, V_Z shifts to ~35.2V; at –40°C, it drops to ~31.2V-still within the 31.35–34.65V initial tolerance band at 25°C, but requiring system-level compensation for precision references.

Can 1SMB5937B-13 be used as a replacement for 1N5937B in existing designs?

Electrically identical in zener parameters, but mechanically incompatible: 1SMB5937B-13 uses SMB surface-mount packaging versus DO-41 through-hole for 1N5937B. Direct replacement requires PCB redesign for SMT pads and reflow profile adjustment-no drop-in compatibility exists.