12 V voltage regulator · TO-220
7812 Pinout
Printed face toward you, metal tab at the back, legs pointing down, left to right: 1 input, 2 ground, 3 output (IN-GND-OUT). The metal tab is joined to the ground.
The 12 V member of the 78xx family: about 14.5 V to 35 V in, a steady 12 V out, up to 1 A to 1.5 A depending on the maker.
- Pin 1: Input (IN)The unsteady supply comes in here: at least about 14.5 V for a 12 V output, never above 35 V.
- Pin 2: Ground (GND)0 V, shared by the input and the output. Also joined to the metal tab, on the TO-220 that has one.
- Pin 3: Output (OUT)A steady 12 V comes out here.
Metal tab: joined to pin 2, the ground, inside the part.
Check your part before wiring. Read the maker and the full part number printed on it, open that maker's datasheet, or test the legs with a multimeter's diode setting.
PNG 1440 × 1280 pixels, SVG to any size. Both keep the wirecora.com mark along the bottom.
Pinout table
Which leg of the 7812 is which?
| Pin | Name | What it does |
|---|---|---|
| 1 | Input IN | The unsteady supply comes in here: at least about 14.5 V for a 12 V output, never above 35 V. |
| 2 | Ground GND | 0 V, shared by the input and the output. Also joined to the metal tab, on the TO-220 that has one. |
| 3 | Output OUT | A steady 12 V comes out here. |
| Tab | Metal tab GND | Joined to pin 2, the ground, so it carries the same voltage. Keep it away from other metal unless you mean it to touch. |
Key ratings
How much can the 7812 take?
From the Texas Instruments datasheet: uA7805, uA7808, uA7810, uA7812, uA7815, uA7824 Positive-Voltage Regulators (SLVS056P). Stay well inside these limits: they are the most the part takes, not what it should run at.
Open the Texas Instruments datasheet (PDF)Pin order by maker
Is every 7812 wired IN-GND-OUT?
TI's uA78 and LM340 datasheets and onsemi's MC7800 number the legs 1 input, 2 ground, 3 output (IN-GND-OUT) with the printed face toward you, and the metal tab is ground.
That is the same order as the 7805, so a 7812 fits a 7805's place and only the output voltage changes. The makers differ on current (1.5 A at TI, 1.0 A at onsemi) and on tolerance (4 % for standard parts, 2 % for A grades).
The negative regulators (the 79xx family) use a different leg order. Do not swap one into a 7812's place.
A first circuit
A steady 12 V for a fan or relay from a 15 V to 24 V supply
- Supply plus (15 V to 24 V) to IN, supply minus to GND.
- A 0.33 µF capacitor from IN to GND, close to the regulator (the datasheets ask for it when the supply's own capacitor is far away).
- A 0.1 µF capacitor from OUT to GND helps when the load changes quickly.
- Take 12 V from OUT and 0 V from GND.
The extra voltage turns into heat: from 18 V at 0.5 A that is 3 W, which needs a heatsink. A 12 V supply is not enough: the input must be about 14.5 V or more.
7812 questions
What is the 7812 pinout?
With the printed face toward you and the legs pointing down, from left to right: input, ground, output (IN-GND-OUT). On the metal-tab TO-220 the tab is ground.
What is the lowest input voltage for a 7812?
About 14.5 V. The regulator needs about 2 V more on its input than the 12 V it gives out. Below that, the output sags with the input.
Can I get 12 V from a 12 V battery with a 7812?
No. With 12 V in, the output stays about 2 V lower. Use the battery directly, or feed the 7812 from 14.5 V or more.
Is the 7812 wired like the 7805?
Yes. Both are IN-GND-OUT with the tab on ground, so the same board takes either; only the output voltage changes. LM7812, L7812 and MC7812 are the same job from different makers.
Why does my 7812 get hot?
Every volt it drops, times the current, is heat. 18 V in and 12 V out at 0.5 A is 3 W. Give it a heatsink or lower the input voltage.
Can I use this pinout picture?
Yes. Download it as PNG or SVG and use it in notes, lessons or posts. The wirecora.com mark along the bottom stays in the picture.
Pin order and ratings from the Texas Instruments datasheet named above. Last reviewed .