LD1117AS33TR Integrated Circuits (ICs)

LD1117AS33TR Application Field and Working Principle

LD1117AS33TR is a linear voltage regulator from STMicroelectronics, an Italian-contact semiconductor manufacturer. As part of their Power Management IC (PMIC) range, this low-dropout linear voltage regulator offers a low-power, low-cost alternative to switching regulators and can output up to 25V at up to 1.2A.

The LD1117AS33TR is an adjustable regulator, allowing the output voltage to be set using a series of external resistors. It has a typical dropout voltage of 2.3V and is designed to provide a stable output even with an input supply up to 30V. The REGAMP pin can be used to achieve a low noise output, making the LD1117AS33TR suitable for powering audio and radio applications.

The LD1117AS33TR is also equipped with short-circuit protection, over-temperature protection, and reverse-current protection, helping to ensure that the device remains stable and robust under adverse conditions. The regulator includes transition-mode control, which helps to reduce power consumption and to eliminate the switching noise generated by other types of voltage regulators.

Working Principle

The LD1117AS33TR operates on the basis of an adjustable voltage feedback loop. The regulator needs to receive a constant input voltage to operate properly, then an internal error-amplifier adjusts the output voltage of the regulator in response to changes in the load current. The error-amplifier compares the voltage at the REGAMP pin to an internal reference voltage and provides an output voltage which is proportionate to the difference between these two values. By adjusting the external resistors, the reference voltage can be changed, adjusting the output voltage accordingly.

The output voltage of the LD1117AS33TR can also be adjusted using an external reference voltage. In this case, an external reference voltage is provided to the REGAMP pin and the voltage at the feedback pin is compared to this external reference. Using this method, the output voltage can be set accurately to any value between 1.25V and 25V.

Conclusion

The LD1117AS33TR is an ideal choice for a wide range of applications requiring low-dropout linear voltage regulation. Its adjustable voltage feedback loop ensures easy and accurate output voltage setting, while its transition-mode control reduces power consumption and eliminates switching noise. The presence of short-circuit protection, over-temperature protection, and reverse-current protection increase the robustness of the device, making it a reliable choice for powering a variety of circuits.