The LM7805 is a three-terminal fixed 5 V linear regulator that can deliver over 1.5 A with adequate heat sinking, has internal current limiting, thermal shutdown and safe-area protection, and needs no output capacitor to stay stable. It is the simplest way to make 5 V from a 7.5 to 20 V battery, and a common source of heat in beginner robots. Figures are from the Texas Instruments LM340 and LM7805 family datasheet SNOSBT0L.
Key specifications
| Output | fixed 5 V (also 12 V, 15 V in family) |
|---|---|
| Current | up to 1.5 A with heat sinking |
| Dropout | 2 V at 1 A |
| Input (spec range) | 7.5–20 V |
| Absolute max input | 35 V |
| Protection | current limit, thermal, SOA |
What the datasheet promises
| Item | Datasheet value |
|---|---|
| Output current | Up to 1.5 A with adequate heat sinking |
| Fixed outputs | 5 V, 12 V and 15 V options in the family |
| Output tolerance | ±2 percent at 25 °C for the LM340A |
| Line regulation | 0.01 percent per volt at a 1 A load (LM340A) |
| Load regulation | 0.3 percent per amp (LM340A) |
| Dropout voltage | 2 V at 1 A, 25 °C (LM7805) |
| Input voltage (5 V part) | Electrical characteristics are specified for 7.5 to 20 V in; the absolute maximum DC input is 35 V |
| Ripple rejection | 68 dB (8 to 18 V input) |
| Protection | Internal thermal overload, short-circuit and safe-area protection |
| Capacitors | Output capacitance is not required for stability; input bypassing is needed only if far from the supply filter capacitor |
| Packages | SOT-223 and others |
The datasheet describes the family as essentially indestructible because of its protection circuits. That means it survives abuse by shutting down, not that it will stay cool: heat is the voltage drop times the current.
The heat problem
From a 12 V battery to 5 V at 500 mA, the regulator drops 7 V and dissipates 3.5 W, which is far more than a bare TO-220 can lose to air, so it needs a heatsink. A buck converter such as the LM2576 or the LM2596 wastes much less. For lower voltage rails, see the LM1117. The 3.5 W is a calculation, not a measurement.
Sources and further reading
- Texas Instruments LM340, LM340A and LM7805 family datasheet (SNOSBT0L) — the current, regulation, dropout, input range and protection above.
Last reviewed: November 2026. Limits are from the Texas Instruments datasheet; regulators from other makers differ. No price is quoted because it has not been checked.
Where to buy in India
These open a store search. Compare seller, price and reviews before you order.