The LM317 device is an adjustable three-terminal positive-voltage regulator capable of supplying up to 1.5 A over an output-voltage range of 1.25 V to 37 V. It requires only two external resistors to set the output voltage. It includes current limiting, thermal overload protection, and safe operating area protection regulators.
- Output Voltage Adjustable From 1.25 V to 37 V
- Output Current -1.5 A
- Maximum input voltage =40V
FIG 1- PINOUT
RESISTOR – DESIGN
Aim – design an voltage regulator of 3.3V
From data sheet of LM317,
Output Voltage Vo = 1.25(1+R2/R1)
3.3 = 1.25(1+R2/R1)
Assume one resistor and find next one.
Let R1 = 220 ohms
3.3 = 1.25(1+R2/220)
Use near standard resistor of 330 ohms