LM317

A constant current source circuit constructed with LM317

Part pinout of LM317T showing its constant voltage reference

The LM317 is a popular variable voltage regulator.^{[citation needed]} It was invented by Robert C. Dobkin and Robert J. Widlar in 1970 while they worked at National Semiconductor.

Specifications

Vout range	1.25 V – 37 V
Vin – Vout difference	3 V – 40 V
Operation ambient temperature	0℃ – 125℃
Output Imax	less than 1.5 A (assuming factory-suggested heat sinking)
Minimum Load Currentmax	10 mA

See also

• Bob Pease, designer of the LM331 and LM337, which are similar voltage references to the LM317
• Bandgap voltage reference
• Brokaw bandgap reference

External links

• Information page about LM317 from National Semiconductor
• Datasheets
  • LM317 datasheet from National Semiconductor (pdf)
  • LM317 datasheet from Fairchild Semiconductor (pdf)
  • LM317 datasheet from ON Semiconductor (pdf)
  • LM317 datasheet from STMicroelectronics (pdf)
  • LM317 datasheet from Texas Instruments (pdf)
• ECE 327: LM317 Bandgap Voltage Reference Example – Brief explanation of the temperature-independent bandgap reference circuit within the LM317.
• The Design of Band-Gap Reference Circuits: Trials and Tribulations – Robert Pease, National Semiconductor (shows LM317 design in Figure 4: LM117)
• LM317 Circuit Schematics and Pinouts
• LM317 tutorial video with example circuits