component
LM317
Public Made by Adomby adom
TI 3-pin adjustable positive linear regulator, TO-220. 1.5 A, 1.25-37 V output. Datasheet-verified.
3D Model
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Symbol & Footprint
Schematic Symbol
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PCB Footprint
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Datasheet
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README
markdownLM317
Texas Instruments · Adjustable linear regulator · TO-220
Classic 3-terminal adjustable positive-voltage linear regulator in a TO-220 package. It holds a 1.25 V reference between OUT and ADJ, so two resistors set any output from 1.25 V to 37 V, delivering up to 1.5 A. Only two external resistors are needed (plus optional caps), and it has internal current limiting and thermal shutdown. The default adjustable bench-and-board regulator; set VOUT = 1.25 V x (1 + R2/R1).
Pinout
| Pin | Name | Type | Function |
|---|---|---|---|
| 1 | ADJ | input | Adjustment pin. Ties to the midpoint of the external R1/R2 divider between OUTPUT and GND to program VOUT = 1.25V x (1 + R2/R1) + I_ADJ x R2. Internal reference holds this pin at 1.25V below OUTPUT. Typical adjustment-pin current is 50 μA (100 μA max). |
| 2 | OUT | power_out | Regulated output. Delivers up to 1.5A over VOUT = 1.25V to 37V (VIN-VOUT differential 3V to 40V). Also electrically bonded to the package TAB for heatsinking. Optional 1 μF output capacitor improves transient response. |
| 3 | IN | power_in | Unregulated input supply. Recommended 3V to 40V above VOUT (absolute max input-to-output differential 40V). Add a 0.1 μF input bypass if the device sits more than 6 inches from the input filter capacitors. |
Key specifications
| Parameter | Value |
|---|---|
| Type | Adjustable positive linear regulator |
| Output voltage | 1.25-37 V (VREF 1.25 V) |
| Output current | 1.5 A |
| Input voltage | up to 40 V (VIN-VOUT <= 40 V) |
| Dropout | ~2 V typ |
| Protection | Current limit + thermal shutdown |
| Package | TO-220 |
| Body (L×W×H) | 10.3 × 4.6 × 15.9 mm (TO-220) |
Ordering variants
Same part, different packaging or reel option.
LM317T (TO-220)LM317KTTR (TO-263)
CAD (KiCad official)
- Symbol:
Regulator_Linear:LM317_TO-220 - Footprint:
Package_TO_SOT_THT:TO-220-3_Vertical - 3D model: TO-220-3 (KiCad packages3D)
- 3D model files:
lm317-etched.step/lm317-etched.glbcarry the MPN laser-etched on the die in a toggleableAdom.LaserEtchgroup (Fusion-ready);lm317.step/lm317.glbare the bare package body.
Provenance
Data extracted from the manufacturer datasheet, not a distributor listing:
- Datasheet: Texas Instruments datasheet (44 pp, sha256
323ec64a58515090, retrieved 2026-08-17, tier: manufacturer) - Extractor:
ds2sf(Claude) — every pin and dimension is cited to a datasheet page; refuses to fabricate. - CAD: KiCad official libraries (CC-BY-SA 4.0).