Onsemi 1N5338BG 1V 5W Zener Diode: Datasheet, Application Circuit, and Replacement Guide

The Onsemi 1N5338BG is a robust 5W Zener diode designed for voltage regulation tasks requiring high power dissipation. With a nominal Zener voltage of 5.1V, this component is widely used in power supplies, voltage clamps, and surge protectors. Its axial-leaded package and glass passivation ensure reliability and stability under demanding conditions.

Datasheet Overview

Key parameters from the datasheet define the diode’s operational limits. The Zener voltage (VZ) is 5.1V at a test current of 200 mA, with a tolerance of ±5%. The device can dissipate 5W of power at a case temperature of 25°C, derating linearly to zero at 200°C. The maximum reverse leakage current is 5 µA, and the dynamic impedance (ZZT) is as low as 2 Ω, ensuring effective regulation. The operating temperature range spans from -65°C to +200°C, making it suitable for industrial environments.

Application Circuit

A typical circuit using the 1N5338BG is a simple voltage regulator. To design a 5.1V output regulator, an input voltage (Vin) must be higher than VZ—e.g., 9V. A series current-limiting resistor (RS) is critical to set the operating current. The formula RS = (Vin - VZ) / IZ calculates its value, where IZ should be within the knee current (IK) and maximum current (IMAX). For a 100 mA load, RS = (9V - 5.1V) / 0.1A = 39 Ω. The diode shunts excess current to ground, maintaining a stable 5.1V output. For enhanced stability, pair it with a capacitor to filter noise.

Replacement Guide

If the 1N5338BG is unavailable, substitutes must match key specs: 5.1V VZ, 5W power dissipation, and axial package. Suitable replacements include:

- NTE5178A: A direct equivalent with similar electrical characteristics.

- Comchip Technology 5W5.1V: Offers comparable performance and reliability.

- Vishay 1N5338B: A cross-manufacturer alternative with identical ratings.

Always verify the forward voltage, impedance, and temperature coefficient to ensure compatibility in critical circuits.

ICGOOODFIND: The Onsemi 1N5338BG is a high-power Zener diode ideal for voltage stabilization in medium-power applications. Its low dynamic impedance and high reliability make it a preferred choice for designers seeking efficient surge protection and regulation. When replacing, focus on matching electrical and thermal properties to maintain system integrity.

Keywords: Zener Diode, Voltage Regulation, Power Dissipation, Surge Protection, Datasheet