L6919E

L6919E Application Field and Working Principle

The L6919E is a monolithic step-down switching controller developed by STMicroelectronics. It supports a wide range of power inputs, offering standard pin-to-pin compatible products across the entire family. It features low-noise operation, extremely low drop-out, 1% high accuracy feedback voltage, soft start, programmable switching frequency triggered by current or voltage, and protection from thermal and ripple over-voltage.

Application Field

The L6919E is primarily intended for two-wire step down Power distribution applications in mobile phones, battery-based devices and any portable product. It is ideal for small DC/DC converters, such as a Power/Audio power supply for audio amplifiers, cell phone and other mobile communication products. It is suitable for AC/DC adaptors and notebooks.

Working Principle

The L6919E is a switching controller that uses pulse width modulation (PWM) to control power delivery. The controller consists of voltage feedback, current sense, clock, PWM comparator, high-side and low-side drivers, power pass and other control logic. When the voltage or current on the input is low, the controller’s PWM comparator is enabled and the output switch is opened and closed rapidly. This results in the output voltage being stepped-down to a lower voltage that matches the input voltage.

The L6919E offers exceptional efficiency by employing the current mode control technique, which continuously monitors the output current signal. This signal is then compared to a reference current, which causes the controller to open or close the switch in order to maintain the desired output current. This current mode control ensures stable output current and eliminates the need for additional components such as external current sensor or additional current loop.

The L6919E additionally offers other features to achieve efficient operation, such as overvoltage protection, undershoot protection, overshoot protection, pulse-by-pulse current limiting, and frequency modulation. It also provides an adjustable soft-start feature, which reduces the start-up inrush current. Additionally, the L6919E features easy to use external feedback circuit with temperature compensation, proper input impedance matching, and output voltage regulation.

Conclusion

The L6919E is a highly efficient step-down DC/DC switching controller that provides excellent performance and stability. It features a current mode control technique, which continuously monitors the output current signal and compares it to a reference current to ensure stable output current. Additionally, the controller offers various added features such as overvoltage protection, undershoot protection, overshoot protection, pulse-by-pulse current limiting, and frequency modulation. The L6919E is ideal for use in mobile phones, battery-based devices, portable products, audio amplifiers, and other applications.