Low-dropout regulator built to survive an automotive supply: it withstands load-dump transients to 60 V and a reverse-battery connection, and it holds regulation with less than 0.6 V of input-to-output headroom. The quiescent current stays low even near dropout, so it suits always-on car electronics running off the battery directly. It delivers 100 mA at a fixed 3.3 V (this option) or 5 V. A rugged linear regulator for 12 V automotive and industrial rails.

Pinout

Pin	Name	Type	Function
1	IN	power_in	Unregulated input, operating range up to 26 V (survives 50 V load dump on LM2931-N, 60 V on LM2931A/C). A 0.1 µF bypass is required if the regulator is remote from the supply filter.
2	GND	power_in	Device ground / return. In TO-220 and DDPAK/TO-263, the tab is electrically connected to GND.
3	OUT	power_out	Regulated output. Delivers fixed 3.3 V or 5 V (±3.8% for A grade) at up to 100 mA. Requires ≥100 µF low-ESR output capacitor for stability.

Key specifications

Parameter	Value
Type	Low-dropout regulator (automotive)
Output current	100 mA
Dropout	< 0.6 V
Transient survival	Load dump to 60 V, reverse battery to -50 V
Quiescent current	Low (~0.4 mA)
Output	3.3 V (fixed option)
Package	TO-220

Ordering variants

Same part, different packaging or reel option.

LM2931T-3.3 (TO-220)
LM2931AT-5.0 (TO-220)
LM2931D (SOIC-8)

CAD (KiCad official)

Symbol: Regulator_Linear2:LM2931-3.3_TO220 (KiCad official)
Footprint: Package_TO_SOT_THT:TO-220-3_Vertical
3D model: TO-220 (KiCad packages3D, STEP)

Provenance

Data extracted from the manufacturer datasheet, not a distributor listing:

Datasheet: Texas Instruments datasheet (35 pp, sha256 45c959192188b8f1, retrieved 2026-08-17, tier: manufacturer)
Extractor: ds2sf (Claude). Every pin and dimension is cited to a datasheet page; it refuses to fabricate.
CAD: KiCad official libraries (CC-BY-SA 4.0).

Datasheet PDF