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L78L18ACUTR

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STMicroelectronics Voltage Regulators - Linear, Low Drop Out (LDO) Regulators, SOT-89-3. Pinout extracted from the datasheet, KiCad symbol/footprint/3D.

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Made with KiCad 10.0 · needs KiCad 10.0 or later to open · KiCad file format 20260206
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docs l78l18acutr: re-etch, flat white mark read from pin 1 (service-occt 1.4.0) + chip hero · Ray
viewers pin 1: carry the footprint's marker into the .lbr, the viewer and page.json (silk-marker, drawn, top-left) · Ray
l78l18acutr-etched.fit.json l78l18acutr: re-etch, flat white mark read from pin 1 (service-occt 1.4.0) + chip hero · Ray
l78l18acutr-etched.glb l78l18acutr: re-etch, flat white mark read from pin 1 (service-occt 1.4.0) + chip hero · Ray
l78l18acutr-etched.step l78l18acutr: re-etch, flat white mark read from pin 1 (service-occt 1.4.0) + chip hero · Ray
l78l18acutr.glb Publish 0.1.0 · Ray
l78l18acutr.kicad_mod Publish 0.1.0 · Ray
l78l18acutr.kicad_sym Publish 0.1.0 · Ray
l78l18acutr.lbr rebuild the library on adom-lbr 2.32.0. The published copy was built by 2.18.0, which imported every KiCad roundrect an… · Ray
l78l18acutr.step Publish 0.1.0 · Ray
package.json pin 1: carry the footprint's marker into the .lbr, the viewer and page.json (silk-marker, drawn, top-left) · Ray
pads.json pin 1: carry the footprint's marker into the .lbr, the viewer and page.json (silk-marker, drawn, top-left) · Ray
page.json l78l18acutr: specified limits as data (metadata.characteristics, 18 rows from the datasheet) · Ray
README.md l78l18acutr: specified limits as data (metadata.characteristics, 18 rows from the datasheet) · Ray

L78L18ACUTR

STMicroelectronics · Voltage Regulators - Linear, Low Drop Out (LDO) Regulators · SOT-89-3

L78L18ACUTR from STMicroelectronics, in a SOT-89-3. 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 VOUT power_out Regulated +18 V output (±4% for 'AC' grade). Delivers up to 100 mA with adequate heat-sinking. A 0.1 µF ceramic capacitor to GND is recommended at the pin to improve transient response and stability.
2 GND power_in Common ground reference for input and output. The SOT-89 large center tab is also connected to GND and serves as the primary thermal path to the PCB copper (Rth(j-c) = 15 °C/W, Rth(j-a) ≈ 55 °C/W with 6 cm² copper).
3 VIN power_in Unregulated positive DC input. For an 18 V output the input voltage must remain within the 35 V absolute maximum (VO = 12-15 V rating in Table 1 extends to 40 V for VO = 18-24 V devices, so VIN(max) = 40 V for the 18 V option). Dropout voltage is typically 1.7 V. A 0.33 µF capacitor from VIN to GND is recommended if the regulator is far from the power-supply filter.

Key specifications

Parameter Value
Manufacturer STMicroelectronics
Package SOT-89-3
Category PMIC
Pins 3

Ordering variants

Same part, different packaging or reel option.

  • L78L18ACUTR
  • L78L18ACUTRZ
  • L78L18ACUTR-AP
  • L78L18ACUTRD
  • L78L18ACUTRD13TR

Electrical characteristics

Limits as printed in the datasheet (page.json metadata.characteristics carries them as data).

Parameter Symbol Min Typ Max Unit Conditions Page
Output voltage (TJ = 25 °C) VO 17.3 18 18.7 V TJ = 25 °C 13
Output voltage VO 17.1 18.9 V IO = 1 to 40 mA, VI = 22 to 33 V 13
Line regulation ∆VO 320 mV VI = 22 to 33 V, TJ = 25 °C 13
Line regulation ∆VO 270 mV VI = 22 to 33 V, TJ = 25 °C 13
Load regulation ∆VO 170 mV IO = 1 to 100 mA, TJ = 25 °C 13
Load regulation ∆VO 85 mV IO = 1 to 40 mA, TJ = 25 °C 13
Quiescent current Id 6.5 mA TJ = 25 °C 13
Quiescent current Id 6 mA TJ = 125 °C 13
Quiescent current change ∆Id 0.1 mA IO = 1 to 40 mA 13
Quiescent current change ∆Id 1.5 mA VI = 23 to 33 V 13
Output noise voltage eN 120 µV B = 10 Hz to 100 kHz, TJ = 25 °C 13
Supply voltage rejection SVR 33 38 dB VI = 23 to 33 V, f = 120 Hz, IO = 40 mA, TJ = 25 °C 13
Dropout voltage Vd 1.7 V 13
DC input voltage (VO = 18 to 24 V) VI 40 V VO = 18 to 24 V 4
Output current IO 100 mA 4
Storage temperature range TSTG -65 150 °C 4
Operating junction temperature range TOP 0 125 °C for L78LxxAC / L78LxxC 4
Thermal resistance junction-ambient RthJA 55 °C/W SOT-89, considering 6 cm² of copper board heat-sink 4

CAD (KiCad official)

  • Symbol: L78L18ACUTR
  • Footprint: Package_TO_SOT_SMD:SOT-89-3
  • 3D model: SOT-89-3 (KiCad packages3D, STEP)
  • 3D model files: l78l18acutr-etched.step / l78l18acutr-etched.glb carry the MPN laser-etched on the die in a toggleable Adom.LaserEtch group (Fusion-ready); l78l18acutr.step / l78l18acutr.glb are the bare package body.

Provenance

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

  • Datasheet: STMicroelectronics datasheet (40 pp, sha256 8b73c521b7f1b36e, 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