STMicroelectronics L78M05CDT-1 Linear Voltage Regulator

Reliable Voltage Regulation for Demanding Applications

In the world of electronic design, maintaining stable power delivery is critical for system reliability. The STMicroelectronics L78M05CDT-1 Linear Voltage Regulator emerges as a proven solution for engineers requiring precise 5V output regulation with robust protection features. Though now marked as obsolete, this TO-251 packaged IC remains widely referenced in legacy systems across industrial automation, consumer electronics, and embedded hardware projects.

Key Performance Specifications

Engineered to deliver consistent performance under varied conditions, this fixed-output regulator accepts input voltages up to 35V while maintaining a stable 5V output. Its 500mA current capability makes it suitable for powering microcontrollers, sensors, and peripheral circuits in both hobbyist and commercial applications. The device incorporates multiple protection mechanisms including thermal shutdown, overcurrent protection, and short-circuit recovery to ensure reliable operation in challenging environments.

Design and Implementation

The TO-251 (IPAK) package combines traditional through-hole mounting with efficient heat dissipation characteristics. This makes the L78M05CDT-1 particularly valuable in applications where board-level mechanical stability is crucial. While modern designs might favor surface-mount alternatives, this regulator's proven reliability keeps it in service across thousands of existing systems worldwide.

For engineers working with this component, proper heatsinking remains essential when operating near maximum current ratings. The device's 6mA quiescent current draw ensures efficient operation in low-power applications, while its 62dB PSRR (Power Supply Rejection Ratio) at 120Hz provides excellent noise suppression for sensitive analog circuits.

Applications and Use Cases

This versatile regulator finds application in a diverse range of systems including:

• Industrial control panels and PLCs
• Consumer electronics power supplies
• Instrumentation and measurement equipment
• Embedded systems and development boards
• Automotive diagnostic tools

Its combination of electrical performance and physical durability makes it particularly well-suited for environments with significant thermal cycling or mechanical vibration.

Legacy Support and Alternatives

While STMicroelectronics has marked the L78M05CDT-1 as obsolete, its widespread adoption means substantial inventory remains available through authorized distributors. Designers seeking modern replacements should consider ST's newer LDO regulators with enhanced efficiency and additional features. However, for maintenance and repair applications, this classic component continues to offer unmatched compatibility with existing designs.

Tags: Voltage Regulator, Power Supply IC, Industrial Electronics, Consumer Electronics, TO-251 Package