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L7818 18 V Linear Regulator

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by Ray

Fixed 18 V positive-voltage linear regulator, up to 1.5 A, in the L78xx (7800) series.

regulatorlinearfixedpositivepmicstto-220
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L7818

STMicroelectronics · Linear Regulator (LDO) · TO-220

The L7818 is a three-terminal fixed positive-voltage regulator from ST's L78xx (7800) series, delivering a stable 18 V output at up to 1.5 A with adequate heat sinking. It powers higher-voltage rails from an unregulated supply, needing only input and output capacitors.

Pinout

Pin Name Type Function
1 INPUT power_in Unregulated DC input supply. Absolute maximum V_I = 35 V for V_O ≤ 18 V variants. A 0.33 µF ceramic bypass to GND is recommended close to the pin for stability when the regulator is far from the bulk filter capacitor.
2 GROUND power_in Common ground reference for both input and output. In TO-220 and TO-220FP this pin is electrically connected to the mounting tab. Return currents for both C_I and C_O bypass capacitors should tie to this pin with a short, low-impedance path.
3 OUTPUT power_out Regulated +18 V output (2 % tolerance on A-version parts). Delivers up to 1.5 A with adequate heatsinking; internally current-limited and SOA-protected. A 0.1 µF ceramic output capacitor is recommended to improve transient response.

Key specifications

Parameter Value
Type Fixed positive linear regulator
Output voltage 18 V
Output current Up to 1.5 A (with heatsink)
Dropout voltage 2 V typ
Package TO-220 (3-lead)
Operating temperature 0 C to 125 C (junction)

Ordering variants

Same part, different packaging or reel option.

  • L7818CV
  • L7818CP
  • L7818CD2T
  • L7818D2T
  • L7818CDT
  • L7818DT

CAD (KiCad official)

  • Symbol: l7818.kicad_sym
  • Footprint: l7818.kicad_mod
  • 3D model: TO-220 body from KiCad Package_TO_SOT_THT/TO-220-3_Vertical.

Provenance

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

  • Datasheet: STMicroelectronics datasheet (55 pp, sha256 ccba643d1b7ced87, 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