The LM2940 is a 1 A low-dropout positive regulator with an input range of 6 V to 26 V, a typical dropout of 0.5 V at 1 A, and protection against reverse battery and load-dump transients. It was designed for vehicles, which makes it a tough choice for a 12 V robot battery. It drops out far less than the LM7805. Figures are from the Texas Instruments LM2940-N and LM2940C datasheet SNVS769J.
Key specifications
| Input | 6–26 V |
|---|---|
| Current | over 1 A |
| Dropout | 0.5 V typical at 1 A (1 V max) |
| Ground current | 30 mA at 1 A, 5 V drop |
| Protection | reverse battery, short circuit, thermal |
| Packages | SOT-223, WSON-8, TO-263, TO-220 |
What the datasheet promises
| Item | Datasheet value |
|---|---|
| Input voltage | 6 V to 26 V |
| Output current | In excess of 1 A |
| Dropout voltage | 0.5 V typical at 1 A; 1 V maximum over temperature |
| Quiescent current | 30 mA with 1 A load and a 5 V input-output difference; higher when in dropout |
| Protection | Reverse battery, mirror-image insertion, internal short-circuit current limit, thermal overload |
| Line transients | Automatically shuts down during load dump when the input exceeds the maximum |
| Output accuracy | Output voltage trimmed before assembly |
| Packages | SOT-223, WSON-8, TO-263 and TO-220 |
The ground current rises when the regulator is in dropout, so the battery drains faster near the end of its range. Heat is the input-output voltage difference times the load current, so a 12 V to 5 V drop at 1 A is a calculated 7 W and needs a switching converter such as the LM2596 instead.
Using it on a robot
- Make a 5 V rail from a battery where the drop is small, for example from a 7 V to 9 V pack.
- Use it as a post-regulator after a switching converter, as the datasheet application list suggests.
- Check the thermal data and heat-sink needs for the package before loading it near 1 A.
Sources and further reading
- Texas Instruments LM2940-N, LM2940C datasheet (SNVS769J) — input range, current, dropout, quiescent current, protection and packages above.
Last reviewed: November 2026. Limits are from the Texas Instruments datasheet; breakout boards and modules vary. 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.