1N5255B

Single Zener Diodes Overview

The Microchip Technology 1N5255B is a silicon unidirectional voltage regulator diode housed in a hermetically sealed glass axial-lead DO-35 (DO-204AH) package. It provides a nominal Zener voltage of 28 V with a standard tolerance of ±5%. The device operates at a test current of 4.5 mA and dissipates up to 0.5 watts at 25°C ambient temperature. Key electrical characteristics include a maximum reverse leakage current of 100 nA, a Zener impedance of 44 Ohms, and a positive voltage temperature coefficient of +0.091 %/°C.

Single Zener Diodes Feature Summary

• Hermetically sealed glass axial-lead construction for reliable operation
• Provides stable voltage regulation across a broad operating current range
• Inherently radiation hard per MicroNote 050
• Minimal capacitance suitable for high-frequency applications

Single Zener Diodes Applications

• Voltage reference circuits requiring stable DC levels
• Overvoltage protection for sensitive electronic components
• Clamping applications in signal processing paths

Single Zener Diodes Procurement Notes

Verify the specific manufacturer source, as this component was originally produced by Microsemi and is now part of Microchip Technology. Confirm that the ordering suffix matches the required tolerance level and packaging format. Ensure compliance with RoHS requirements if applicable by checking for the e3 suffix designation on the datasheet or purchase order.

Single Zener Diodes Selection Notes

Select this component when a precise 28 V regulation point is needed within a compact axial-lead form factor. The ±5% tolerance offers a balance between cost and precision compared to tighter tolerance variants. Consider the thermal resistance and derating curves if the application involves elevated ambient temperatures or limited board space for heat dissipation.

Single Zener Diodes Part Context

This device belongs to the 1N5221 through 1N5281B series of 0.5 W Zener Voltage Regulators. The series covers a wide voltage selection from 2.4 V to 200 V. The 'B' suffix specifically denotes a standard 5% voltage tolerance, distinguishing it from 'A' (10%), 'C' (2%), and 'D' (1%) tolerance options within the same JEDEC registered family.

Single Zener Diodes Replacement Considerations

Surface mount equivalents are available in the MLL5221 to MLL5281B series using the DO-213AA MELF style package. For military screening requirements, prefixes such as MQ, MX, MV, or MSP can be added to part numbers with the '-1' suffix to meet MIL-PRF-19500 standards.

Single Zener Diodes FAQ

What is the polarity indication for the 1N5255B?

The cathode end is indicated by a color band on the glass body. The diode must be operated with the banded end positive with respect to the opposite end for Zener regulation.

How is the Zener impedance measured?

It is derived from the 60 Hz AC voltage resulting when an AC current with an RMS value equal to 10% of the DC Zener current is superimposed on the DC current. Measurements are taken at two points to ensure a sharp knee on the breakdown curve.