L78L09CD13TR

L78L09CD13TR Application Field and Working Principle

The L78L09CD13TR is a three-terminal positive voltage regulator specifically designed to provide a regulated output voltage of 9V and a maximum output current of 100mA. It also features classic TO-92 package, which makes it suitable for a variety of applications. It is largely applied in battery-powered systems, especially those that require a highly efficient and cost-effective power supply.

Applications

• Battery chargers
• Battery-powered appliances
• Low-voltage DC-DC converters
• Supply systems of STM microprocessors
• LED lighting and other applications.

Features

• Maximum input voltage of 35V
• Low quiescent current
• Current foldback performance
• Thermal shutdown protection
• Soft-start circuitry
• Reverse polarity protection.

Working Principle

The L78L09CD13TR operates as a linear regulator when powered. It consists of an internal voltage reference, three error amplifiers, an on-chip temperature sensor, and an output switch. All these components help to maintain the accuracy of the output voltage. When the output voltage falls lower than the reference voltage, the error amplifiers detect this difference, which causes it to switch on the output switch. This ensures a constant regulated output voltage.

The output voltage regulation is achieved by controlling the amount of current flowing into the output transistor. The low quiescent current of the L78L09CD13TR is one of its outstanding features. It keeps the device in a low power state until it needs to be active. This ensures a highly efficient performance and also extends the battery life of the system.

The thermal shutdown protection of the L78L09CD13TR helps it protect against over-temperature conditions. The device automatically shuts down when the internal temperature exceeds its maximum operating junction temperature. This prevents any damage caused by excessive heat. In addition, the device also features reverse polarity protection which protects it against accidental reverse connection of power sources.

The L78L09CD13TR also offers soft-start circuitry and current foldback performance. The soft-start circuitry helps to reduce in-rush current when the device is powered on. The current foldback performance helps to reduce the load current when the load current is too high, effectively protecting the device against over-load conditions.

Conclusion

The L78L09CD13TR is a three-terminal positive voltage regulator. It is mostly applied in battery-powered systems, especially those that require a highly efficient and cost-effective power supply. It features a maximum input voltage of 35V, low quiescent current, current foldback performance, thermal shutdown protection, soft-start circuitry and reverse polarity protection. All these features make it ideal for use in a wide range of applications.