LM7812 Fixed Linear Voltage Regulator (+12V) — Datasheet, Pinout & Circuit
The LM7812 is a positive fixed linear regulator from Texas Instruments. The LM7812 is a three-terminal fixed linear voltage regulator that provides a stable +12V output with a maximum current of 1A. Ideal for powering operational amplifiers and analog circuits.
What is the LM7812?
The LM7812 is a Positive fixed linear regulator from the 78xx series by Texas Instruments. Primary applications:
- Operational amplifiers
- Analog circuits
- Small DC motors
- Relays and solenoids
- Audio systems
- High-power LEDs
Key Specifications
- Output Voltage: 12V (fixed)
- Maximum Current: 1A
- Type: Positive fixed linear regulator
- Package: TO-220
- Dropout Voltage: 2V
Datasheet and Pinout
Pin configuration of LM7812 regulator in TO-220 package
| Pin | Name | Function |
|---|---|---|
| 1 | IN | Input voltage (14V-35V) |
| 2 | GND | Ground |
| 3 | OUT | Output voltage (+12V) |
📄 Official Datasheet: Download PDF
TO-220 Visual identification: With the flat side facing you and pins pointing down, the pins run left to right as shown in the table above.
Technical Specifications
| Parameter | Value |
|---|---|
| Output Voltage | 12V (fixed) |
| Maximum Current | 1A |
| Regulator Type | Linear |
| Package | TO-220 |
| Dropout Voltage | 2V |
| Manufacturer | Texas Instruments |
| operating Voltage | 12V ±4% (output) |
| max Current | 1A |
| temperature | 0°C to +125°C |
| package Type | TO-220 |
| dropout | 2V typical |
| regulation | 4% maximum |
| ripple Rejection | 55dB typical |
Typical Circuit
The LM7812 requires minimal external components. The basic circuit includes:
- Input capacitor (C1): 0.1 µF – 1 µF (ceramic or electrolytic) between VIN and GND — filters input noise.
- Output capacitor (C2): 1 µF – 10 µF (electrolytic) between VOUT and GND — stabilizes output and improves transient response.
⚠️ Always add a heatsink if current exceeds 500mA or if the Vin – Vout difference is greater than 3V. Power dissipated: P = (Vin – Vout) × Iload.
Variants and Alternatives
| Component | Vout | Imax | Type |
|---|---|---|---|
| 78L12 | — | — | Alternative |
| 7812 | — | — | Alternative |
| MC7812 | — | — | Alternative |
| L7812 | — | — | Alternative |
Applications with Arduino and DIY Projects
The LM7812 is ideal for projects requiring a clean, regulated supply:
- Power Arduino from 12V: Converts to 12V (fixed) for the Arduino VIN pin.
- Breadboard prototypes: Minimal circuit (IC + 2 capacitors) fits any breadboard.
- Audio projects: Stable voltage for op-amps and audio amplifiers.
- Sensors and modules: Clean supply for DHT11, ultrasonic sensors, etc.
Frequently Asked Questions (FAQ)
What is the LM7812 used for? It is a Positive fixed linear regulator that converts a higher input voltage into a stable 12V (fixed) output. The LM7812 is a three-terminal fixed linear voltage regulator that provides a stable +12V output with a maximum current of 1A. Ideal for powering operational amplifiers and analog circuits.
How much current can the LM7812 supply? Up to 1A continuously with an adequate heatsink. Without a heatsink, limit to 100–200 mA to prevent overheating.
Does the LM7812 need a heatsink? Yes, when power dissipation P = (Vin – Vout) × I exceeds ~1W. For light loads (under 200 mA) with a small voltage difference, it can operate without a heatsink.
What is the difference between LM7812 and its alternatives? The 78L12 is a direct pin-compatible alternative. The main difference is usually the manufacturer (TI, Fairchild, ST) and slight variations in datasheet specifications.
Where can I buy the LM7812? At local electronics stores, eBay, Mouser, DigiKey, or AliExpress. For prototyping, breakout modules that include the IC with capacitors already mounted are also available.
What is the LM7812 pinout? See the pinout table above. For the TO-220 package: with the flat side facing you and pins pointing down, the pin order is shown left to right in the table. Download the official datasheet for the complete diagram.