Is there a pin-compatible replacement for LM2940S-3.3?

No, a direct pin-compatible replacement has not been identified among common alternatives. The popular AMS1117 series, also in a SOT-223 package, has a different pinout and will not work as a drop-in replacement.

What risks should I check before replacing LM2940S-3.3?

Before replacing, you must verify three critical points: 1) Package footprint, as most alternatives are in different packages. 2) Pinout, as even parts in similar packages may be incompatible. 3) Maximum input voltage, as many substitutes cannot handle the target's 26V rating.

LM2940S-3.3 Alternatives, Datasheet & Cross Reference | Tak Cheong Electronics (Holdings) Co., Limited

LM2940S-3.3 is a 3.3V, 1A LDO in a SOT-223 package, notable for its high 26V input voltage. Finding a direct replacement is challenging due to this high voltage rating and specific pinout, requiring careful review of alternatives.

AI replacement insight

Package riskhigh

Most alternatives are in different packages or have incompatible pinouts (e.g., AMS1117).

Electrical riskhigh

Many alternatives have a lower maximum input voltage, creating a risk of failure in the application.

Can it be replaced directly?

No direct pin-to-pin replacement is readily available due to the target's specific combination of high input voltage (26V), SOT-223 package, and pinout.

Best replacement path

Redesign the PCB for a functional alternate. For an electrical upgrade, use a part like LM29150RS-3.3 in a DPAK package. For a more common part, consider the AMS1117 series, but be aware of its incompatible pinout and lower input voltage.

Main risk

Pinout incompatibility and lower input voltage ratings on most alternatives.

Recommended alternatives

An electrical upgrade in a different package, suitable if a PCB layout change is possible.

View details

Alternative comparison matrix

Feature / factor	LM2940S-3.3	LM29150RS-3.3	AMS1117-3.3	ME6118A33PG	Compatibility / risk
Package	SOT-223-3L	TO-252 (DPAK)	SOT-223	SOT89-3	TO-252 (DPAK) / SOT-223 / SOT89-3 — Different footprint and thermal characteristics. Requires PCB redesign.; AMS1117-3.3: Package name matches, but pinout is different. Not a drop-in replacement.; ME6118A33PG: Different footprint and thermal characteristics. Requires PCB redesign.
Voltage	3.3V	3.3V	15V-18V	3.3V	3.3V / 15V-18V — Fixed output voltage matches.; AMS1117-3.3: Max input voltage is lower than target's 26V. Check specific datasheet.; ME6118A33PG: Fixed output voltage matches.
Current	1.0A	1.5A	1.0A	1.0A	1.5A / 1.0A — Higher output current capability.; AMS1117-3.3: Output current matches the target.; ME6118A33PG: Output current matches the target.
Pinout	VIN, VOUT, GND	-	GND, VOUT, VIN	-	GND, VOUT, VIN — Pin functions are in a different order. Requires PCB redesign.

Application & sourcing insights

Questions & answers

The best alternative depends on design flexibility. For an electrical upgrade, consider a part like LM29150RS-3.3, but this requires a new PCB layout. For a similar package, the AMS1117 series is common but has an incompatible pinout and lower voltage rating, also requiring a redesign.