LD1117S25CTR from STMicroelectronics, in a SOT-223. Pinout and pin descriptions extracted from the manufacturer datasheet by ds2sf; symbol, footprint, and 3D from KiCad-official CAD.

Pinout

Pin	Name	Type	Function
1	GND	power_in	Ground reference for the fixed-voltage LD1117 (this pin is labeled ADJ/GND in the datasheet; on fixed-output versions such as the LD1117#25 it is the ground return). Connect to system ground; the output-capacitor return should share this node.
2	VOUT	power_out	Regulated 2.5 V output pin. Delivers up to 800 mA. Requires a minimum 10 uF capacitor to ground for loop stability. Electrically tied to the SOT-223 TAB (heatsink pad).
3	VIN	power_in	Unregulated DC input. Absolute maximum 15 V (18 V when IOUT < 20 mA). Dropout is ~1 V typical, so VIN must exceed VOUT + 1 V under full load. A local input decoupling capacitor is recommended.
TAB	VOUT	power_out	Thermal/heatsink tab on the SOT-223 package. Electrically connected internally to VOUT (pin 2). Solder to a copper pour that also serves as the VOUT trace to spread heat (RthJC = 15 degC/W, RthJA = 110 degC/W for SOT-223).

Key specifications

Parameter	Value
Manufacturer	STMicroelectronics
Package	SOT-223
Category	PMIC
Pins	4

Ordering variants

Same part, different packaging or reel option.

LD1117S25TR
LD1117S25CTR
LD1117S25CTR-DG13
LD1117DT25TR
LD1117DT25CTR
LD1117V25
LD1117V25C

CAD (KiCad official)

Symbol: LD1117S25CTR
Footprint: Package_TO_SOT_SMD:SOT-223-3_TabPin2
3D model: SOT-223 (KiCad packages3D, STEP)

Provenance

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

Datasheet: STMicroelectronics datasheet (46 pp, sha256 eb9bdaeee6a99a12, retrieved 2026-08-17, tier: lcsc)
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