# LM2940 LDO: 1 A, 6 to 26 V in, 0.5 V dropout, reverse-battery safe

> A 1 A low-dropout regulator built for vehicles and 12 V robots: input range, dropout, protection and packages.

Canonical: https://roboticsengineering.in/components/lm2940-1a-ldo/ | Published: 2026-11-03 | Updated: 2026-11-03

**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](https://roboticsengineering.in/components/lm7805-fixed-regulator/). 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](https://roboticsengineering.in/components/lm2596-buck-converter/) 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)](https://www.ti.com/lit/ds/symlink/lm2940-n.pdf) — 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.