L78L09ACUTR Linear Voltage Regulator IC - 9V Fixed Output, 100mA, SOT-89-3 Package

High-Performance Voltage Regulation with L78L09ACUTR from STMicroelectronics

In modern electronic design, reliable voltage regulation is critical for ensuring component longevity and system stability. The L78L09ACUTR from STMicroelectronics offers a robust solution for engineers requiring precision 9V fixed output regulation in compact surface-mount applications. This 100mA linear regulator combines advanced protection features with thermal management in a space-saving SOT-89-3 package, making it ideal for industrial control systems, consumer electronics, and automotive subsystems where stable power delivery is paramount.

Technical Excellence in Linear Regulation

Engineered with STMicroelectronics' proprietary BCDMOS process, the L78L09ACUTR delivers exceptional performance metrics while maintaining backward compatibility with industry-standard voltage regulator footprints. Its fixed 9V output eliminates external resistor network requirements, simplifying design while ensuring ±4% output accuracy across operating conditions. The device operates reliably with input voltages up to 30V, providing ample headroom for fluctuating power sources in real-world applications.

Key technical specifications include:

Advanced Protection Architecture

Built with three layers of protection, this regulator ensures reliability in demanding environments. The integrated thermal shutdown circuitry prevents damage from excessive junction temperatures, while the fold-back current limiting protects against short circuits and overloads. Additionally, a dedicated over-current protection mechanism safeguards both the regulator and connected components from electrical stress, significantly improving system durability.

The device's surface-mount SOT-89-3 package offers excellent thermal dissipation characteristics through its exposed pad design. This feature enables reliable operation across the full industrial temperature range of 0°C to 125°C without derating, making it suitable for applications in harsh operating environments.

Design Flexibility and Application Versatility

While optimized for fixed 9V regulation, the L78L09ACUTR's design allows adaptation to various voltage conversion requirements through external circuitry modifications. Its low dropout characteristics (though not specified in absolute terms) make it particularly effective in battery-powered applications where maintaining regulation during voltage depletion is crucial.

Typical applications include:

• Microcontroller power supplies
• Industrial sensor interfaces
• Portable electronic devices
• Automotive control modules
• Instrumentation systems

The regulator's 44dB power supply rejection ratio at 120Hz ensures clean DC output even when powered from noisy sources, reducing the need for additional filtering components in many designs.

Manufacturing and Packaging Advantages

Supplied in tape-and-reel packaging (TR), the L78L09ACUTR supports automated pick-and-place manufacturing processes. With a minimum order quantity of 1 unit and available inventory of 14,287 pieces, it offers flexible procurement options for both prototyping and volume production. The TO-243AA package footprint ensures compatibility with standard PCB layouts while its compact size supports modern miniaturization requirements.

Performance Comparison with Similar Regulators

When compared to competing solutions in the same current class:

This comparison demonstrates the L78L09ACUTR's superior combination of performance and protection features relative to market alternatives.

Design Considerations and Best Practices

For optimal performance, designers should follow these recommended practices:

• Use low-ESR ceramic capacitors at both input and output (typically 10µF input / 1µF output)
• Provide adequate copper area for thermal management
• Minimize trace lengths to voltage reference pin
• Implement proper grounding techniques

The device's 5.5mA typical quiescent current makes it suitable for low-power applications where efficiency matters. When calculating power dissipation, engineers should consider the (VIN - VOUT) × IOUT formula to ensure proper thermal design.

Market Availability and Procurement

With a unit price of $0.66 at 1 quantity and volume pricing down to $0.06 per unit at 172,500 quantity, the L78L09ACUTR offers exceptional value for its performance class. Its active production status and ample stock availability ensure supply chain reliability for long-term projects. The component's compatibility with standard reflow soldering processes further reduces manufacturing complexity.

Future-Proof Design Solution

As industries transition toward more compact and energy-efficient systems, the L78L09ACUTR's combination of small form factor, thermal resilience, and comprehensive protection features positions it as a future-proof solution for modern power regulation needs. Whether developing next-generation IoT devices or upgrading legacy systems, this regulator provides the reliability and performance engineers demand.

Tags: L78L09ACUTR, STMicroelectronics, Voltage Regulator, SOT-89-3, 100mA IC