component

AMS1117-3.3

Public Unreviewed

by Ray

AMS 1 A low-dropout fixed 3.3 V regulator, SOT-223. 1.3 V dropout at 0.8 A, internal current + thermal limit. Datasheet-verified.

componentvoltage-regulatorldo3v3sot-223power
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Contents

README

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AMS1117-3.3

Advanced Monolithic Systems · 1 A LDO regulator (fixed 3.3 V) · SOT-223

The 3.3 V version of the AMS1117, a 1 A low-dropout linear regulator in the small SOT-223 tab package that powers a huge number of 3.3 V boards. It holds the output at a fixed 3.3 V with 1.5% reference tolerance and needs only about 1.3 V of headroom at 0.8 A, so a 5 V rail regulates down cleanly. Internal current limiting and thermal shutdown protect it against overload. A 10 uF output capacitor keeps it stable. The tab (pin 2) is the output and the thermal path.

Pinout

Pin Name Type Function
1 GND power_in Ground reference for the fixed-voltage regulator. Also serves as the negative-side sense point; the top of the internal output divider (R1) is Kelvin-connected to the output tab internally.
2 VOUT power_out Regulated 3.3V output; 3.251-3.349 V at TJ=25C, VIN=4.8V. Rated 1A continuous with maximum 1.3V dropout at 0.8A. Requires a 22uF solid tantalum output capacitor for loop stability. Internally shared with the SOT-223 tab (pin 4).
3 VIN power_in Unregulated input supply. Absolute maximum 15V. Requires (VIN - VOUT) >= 1.1-1.3V dropout at up to 0.8A to remain in regulation; recommended VIN = 4.75V for the 3.3V version.

Key specifications

Parameter Value
Type Fixed LDO linear regulator
Output voltage 3.3 V (1.5% tol)
Output current up to 1 A
Dropout 1.3 V max at 0.8 A
Protection Current limit + thermal shutdown
Output cap 10 µF (stability)
Package SOT-223 (tab = VOUT)
Line regulation typ. 0.2%

Ordering variants

Same part, different packaging or reel option.

The extractor listed these alongside AMS1117-3.3, but they are different parts with different electrical characteristics. Do not order them as substitutes.

  • AMS1117-3.3 (SOT-223)
  • AMS1117-3.3/TR (SOT-223, tape & reel)

CAD (KiCad official)

  • Symbol: Regulator_Linear:AMS1117-3.3
  • Footprint: Package_TO_SOT_SMD:SOT-223-3_TabPin2
  • 3D model: SOT-223 (KiCad packages3D)

Provenance

Data extracted from the manufacturer datasheet, not a distributor listing:

  • Datasheet: Advanced Monolithic Systems datasheet (8 pp, sha256 189a2651878a87d5, retrieved 2026-08-17, tier: manufacturer)
  • Extractor: ds2sf (Claude). Every pin and dimension is cited to a datasheet page; it refuses to fabricate.
  • CAD: KiCad official libraries (CC-BY-SA 4.0).

Datasheet PDF