What Is the LM7812 (7812)? 12V Regulator: Pinout and Uses
The LM7812 (7812) is a linear voltage regulator with a fixed +12 V output. It is from the same 78xx family as the LM7805; the difference is the output voltage. Because dropout is ~2 V, the input must be at least ~14.5 V. It supplies clean power to 12 V blocks such as op-amps, relays and fans; it is inefficient and needs a heatsink.
The LM7812 (7812) is a linear voltage regulator that gives a fixed +12 V output. It belongs to the same 78xx family as the LM7805; the only difference is the output voltage. For the concept, see what is a voltage regulator.
What is the LM7812 used for?
It provides a stable supply to blocks that need 12 V, such as op-amp circuits, relay drivers, fans and LED strips. It is typically used to produce clean 12 V from a rectified transformer/adapter output.
LM7812 pinout (TO-220)
| Pin | Function |
|---|---|
| 1 | INPUT (Vin) |
| 2 | GND (ground) |
| 3 | OUTPUT (+12 V) |
Key electrical specifications
| Parameter | Typical value |
|---|---|
| Output voltage | +12 V (fixed) |
| Maximum input | ~35 V |
| Output current | ~1 A (with heatsink) |
| Dropout | ~2 V (Vin must be ≥ ~14.5 V) |
Heat and efficiency
The 7812 is also linear: it produces (Vin − 12 V) × current as heat. If the input is very close to 12 V it cannot regulate because of the dropout; at least ~14.5 V is needed. At high current or a large difference, a switching solution (e.g. the LM2596) is more efficient.
Limitations
- Input must be ≥ ~14.5 V (dropout).
- Inefficient; needs a heatsink for the heat.
- Does not step up; cannot exceed the input.
LM7812 equivalents and alternatives
- LM7805 / LM7809: the 5 V / 9 V versions.
- 78L12: the small 100 mA version.
- LM7912: the negative (−12 V) counterpart.
- LM2596: an efficient buck alternative.
Find it in our catalog
To compare price and stock for the LM7812 and its alternatives, use the 7812 search.