L78L09ACZ

The L78L09ACZ is a fixed 9 V positive linear regulator from the L78L family. It delivers a steady 9 V output from a higher Vin with a typical load current up to about 100 mA. It’s a simple, low-cost solution for small, low-power circuits, with power dissipation determined by (Vin − 9 V) × Iout, so keep Vin close to 9 V or provide adequate heat sinking. The device usually tolerates Vin up to about 15 V (absolute max around 20 V) and includes protection features such as current limiting and thermal shutdown. It’s available in small packages (e.g., TO-92, SOT-89; ACZ suffix specifies the package). Pinout depends on the package, but commonly (front view) the order is Input, Ground, Output; always verify with the datasheet for your package. Typical applications include supplying 9 V rails for microcontrollers, sensors, and other modest-load electronics in battery-powered or low-power systems.

Equivalent parts to L78L09ACZ (9V fixed, ~100 mA, 3‑pin regulator):
- LM78L09 (National/TI) – 9V, 100 mA
- KA78L09 (Fairchild/Renesas) – 9V, 100 mA
- MC7809 (ON Semiconductor) – 9V, ~1 A variant (pinout similar)
- L78L09 (ST) – same 9V, 100 mA family
Note: check exact pinout, dropout, and max input for your board.

Key features of L78L09ACZ (9V fixed regulator):
- Fixed output: 9 V
- Output current: up to ~100 mA
- Input voltage range: up to about 20 V (minimum above 9 V to regulate)
- Low dropout: roughly 0.7–1.0 V at 100 mA
- Protection: short-circuit protection and thermal shutdown
- Internal current limiting
- Packaging: TO-92 style (ACZ) for easy through-hole mounting
Note: exact numbers can vary by manufacturer; consult the datasheet for precise tolerances and limits.

- Pin count: 3 pins (TO-92 package).
- Function: Fixed positive linear voltage regulator (L78L09 series) that provides a regulated 9 V output from a higher input, typically up to ~100 mA.

- Manufacturer: STMicroelectronics (ST).
- What kind of company: A multinational semiconductor and electronics company that designs, manufactures, and markets integrated circuits and electronic components for a wide range of applications.

L78L09ACZ is a fixed 9V, low-current linear regulator (≈100 mA max).
Common application areas:
- Small power supplies and embedded projects needing a 9V rail.
- Pre-regulation stage to feed downstream 5V/3.3V regulators in compact designs.
- Powering analog/digital circuits (op-amps, sensors, microcontrollers) when a 9V rail is convenient.
- Educational/hobby kits, consumer electronics, instrumentation, audio equipment.
- Automotive/industrial sensor interfaces requiring a simple, low-cost 9V regulator.
Notes: input voltage up to ~25V, dropout around ~2V at full load.

L78L09ACZ is in a TO-92 3-pin plastic package (through-hole).