1N4778

Overview

The Microchip Technology 1N4778 is a temperature-compensated Zener diode designed for precision voltage reference applications. It features an 8.5 V nominal Zener voltage with a ±5% tolerance and a power dissipation rating of 500 mW. The device utilizes a silicon planar structure housed in a DO-35 (DO-204AH) axial through-hole package. This component is engineered to provide stable voltage regulation across varying thermal conditions, making it suitable for circuits requiring reliable reference voltages.

Feature Summary

• Temperature compensated design for enhanced voltage stability
• Precision 8.5 V Zener voltage specification
• Robust 500 mW power dissipation capability
• Hermetic sealed construction for reliability

Applications

• Precision voltage reference circuits
• Temperature compensated regulator designs
• Overvoltage protection in sensitive electronics
• Benchmark voltage sources for measurement systems

Procurement Notes

Verify the manufacturer origin, as the 1N4778 part number is utilized by multiple vendors including Microchip and International Semiconductor Inc. Confirm the specific package type and hermetic sealing status required for your application. Ensure the datasheet matches the exact electrical tolerances and temperature coefficients needed for your design specifications before finalizing procurement.

Selection Notes

Select this component when a stable 8.5 V reference is required under fluctuating thermal conditions. The temperature-compensated characteristic distinguishes it from standard Zener diodes, offering superior performance in precision analog applications. Consider the DO-35 package constraints for PCB layout and ensure the 500 mW power rating aligns with the expected current draw in the target circuit design.

Part Context

This component belongs to the family of temperature-compensated Zener diodes, often referred to as BZX series equivalents or precision references. Unlike standard Zeners that exhibit significant voltage drift with temperature, these devices utilize a combination of Zener and avalanche breakdown mechanisms to achieve a near-zero temperature coefficient around the specified voltage point.

Replacement Considerations

Check for direct substitutes such as the 1N4778A or equivalent parts from other manufacturers like ON Semiconductor or Vishay. Verify that replacement units maintain the same 8.5 V nominal voltage, ±5% tolerance, and DO-35 package form factor to ensure mechanical and electrical compatibility.