What Is the LM7805 (7805)? 5V Regulator: Pinout, Wiring and Uses
The LM7805 (7805) is a very easy-to-use linear voltage regulator with a fixed +5 V output. It is the most common member of the 78xx family, producing clean 5 V from a ~7–35 V input (dropout ~2 V). Because it turns the difference into heat, a heatsink is needed; for efficiency with a large difference/high current use a buck like the LM2596.
The LM7805 (7805) is a very easy-to-use linear voltage regulator that gives a fixed +5 V output. It is the most common member of the 78xx family: feed it a higher, noisy DC input and get a clean, steady 5 V out. For the concept, see what is a voltage regulator.
What is the LM7805 used for?
It produces a stable 5 V for microcontrollers and logic circuits from an adapter, battery or rectified source. It works with just one capacitor on the input and output; it needs few external parts. Because efficiency is low (the difference becomes heat), it is ideal for small-to-medium 5 V needs.
LM7805 pinout (TO-220)
| Pin | Function |
|---|---|
| 1 | INPUT (Vin) |
| 2 | GND (ground) |
| 3 | OUTPUT (+5 V) |
The metal tab is connected to GND and mounts to a heatsink.
Key electrical specifications
| Parameter | Typical value |
|---|---|
| Output voltage | +5 V (fixed) |
| Maximum input | ~35 V |
| Output current | ~1 A (with heatsink) |
| Dropout | ~2 V (Vin must be ≥ ~7 V) |
| Quiescent current | ~5–8 mA |
Capacitors and heat
For stability, typically a 0.33 µF cap on the input and 0.1 µF on the output are used. The regulator dissipates (Vin − 5 V) × output current as heat; e.g. at 12 V input and 0.5 A it heats ~3.5 W → a heatsink is a must. For efficiency with a large input-output difference and high current, use a switching regulator like the LM2596 instead of a linear one.
Limitations
- Inefficient; the difference voltage becomes heat.
- ~2 V dropout; if the input is near 5 V it cannot regulate (use an LDO, e.g. the AMS1117).
- Cannot output above the input (does not step up).
LM7805 equivalents and alternatives
- LM7809 / LM7812: the 9 V / 12 V versions of the same family.
- 78L05: the small 100 mA (TO-92) version.
- LM2596: a switching buck — efficient with a large difference/high current.
- AMS1117: low dropout (LDO), popular for 3.3 V.
Find it in our catalog
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