LM317T Voltage Regulator with Pass Transistor

Control of LM317T PDM Stabilizer LM317 is one of the most widely used voltage stabilizers. It provides 1.25V - 37V output voltage фтв 1.5А current. Generally, a potentiometer is used to adjust the output voltage. The diagram demonstrates use of the analog voltage as a potentiometer generating PDM signal. PDM parameters may be set by an external controller or any other digital integrated circuit. PDM signal may be converted into DC voltage by RC low-frequency filter and an operating amplifier. It provides voltage adjustment of LM317 stabilizer output level. Alteration in relative PDM pulse duration provides generation of 0V -- 5V analog voltage at the filter output. Operating amplifier increases the voltage to a required rate. Alteration in R4 and R2 resistor ratings provides required amplification. Capacity of С1 and R1 filter resistor depends on PDM signal frequency. The diagram includes rates for a frequency of 1kHz.



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