LM317LDG

LM317LDG is an adjustable 3-terminal voltage regulator made by ST Microelectronics. It is part of the adjustable, high performance, rad-hard family of linear voltage regulators and belongs to the PMIC (Power Management IC) range. The LM317LDG offers improved reliability, enhanced accuracy and improved transient performance compared with the equivalent standard ICs. The application fields mainly include general purpose, low-noise, LED drive and solar energy.

The LM317LDG is commonly used in systems requiring a regulated current input. It is designed to provide an adjustable regulator with output voltage ranging from 3.0V to 37V and output currents up to 1.2A. The LM317LDG is a rad-hard part, capable of operation up to 400Vdc. It has an operating temperature range of -65 to +150 C, suitable for varied environment.

The adjust pin of the LM317LDG provides a feedback path that can be used to adjust the output voltage or to provide a reference voltage. The output voltage level can be adjusted from 3.0V to 37V with a single feed input voltage of±0.4V. The output current is capable of running up to 1.2A continuous and can be further limited with external components. The LM317LDG provides improved output accuracy (±1%) and low noise (5μVrms) over the standard ICs.

The working principle of LM317LDG relies on an internal voltage reference and an error amplifier. The error amplifier monitors the output voltage level using the adjust terminal and compares it to the reference voltage. If the voltage is higher than the set point, the error amplifier drives the output voltage towards its rated voltage; vice versa if the voltage is lower than the set point. To enable this cycle to start, two external resistors are necessary: one from the adjust terminal to ground, and the other from the adjust terminal to output terminal.

In short, the LM317LDG is part of an adjustable, high performance, rad-hard family of linear voltage regulators, suitable for varied application fields such as general purpose, low-noise, LED drive and solar energy. It is designed to provide small size and low power consumption, with an output voltage ranging from 3.0V to 37V and output current up to 1.2A. The adjustable feedback loop allows users to set the output voltage from 3.0V to 37V with a single feed input voltage of±0.4V. The error amplifier in the LM317LDG ensures that the output voltage can be accurately maintained and low noise is obtained.