Pololu 12V Step-Up Voltage Regulator U3V40F12

Need a clean 12V rail from a lower-voltage battery or supply? The Pololu U3V40F12 is a compact, high-efficiency boost (step-up) regulator that generates 12V (±4%) from inputs as low as 1.3V (with a 2.7V minimum startup). It’s built for real loads with an actively limited high-current switch and multiple protections, while staying breadboard/perfboard friendly thanks to its 0.1" pin spacing and included header options.

Output: fixed 12V with 4% accuracy.
Input: 1.3V–12V (must start at ≥2.7V; can run lower after startup).
Efficiency: typically 85%–95% depending on VIN/load.
Power behavior: power-save mode keeps switching above audible range (>20kHz) for better light-load efficiency.
Protections: over-temperature shutdown, soft-start, output over-voltage protection (~16.5V), and input current limiting.

Why/Benefits

Small but serious boost converter

Actively limits instantaneous input current to 9.5A while boosting (helps protect the regulator). :contentReference[oaicite:6]{index=6}
Can handle ~3.5A input current for prolonged durations (thermal/conditions dependent). :contentReference[oaicite:7]{index=7}
Low no-load draw (typically <2mA). :contentReference[oaicite:8]{index=8}

Friendly for prototyping

0.1" pin spacing for breadboards/perfboards; solder wires or headers.
Includes straight or right-angle 6×1 header strip options in the box.
Compact: 15.2 × 15.2 × 5.6mm; 1.5g.

Technical specifications

Model	Pololu 12V Step-Up Voltage Regulator U3V40F12
Output voltage	12V (±4% accuracy)
Input voltage	1.3–12V (2.7V minimum startup)
Typical max input current	3.5A (continuous depends on thermals & VIN)
Instantaneous input current limit	9.5A while boosting
Efficiency	Typical 85%–95%
Switching frequency	~600kHz under heavy loads
Quiescent current	Typically <2mA (no-load)
Protections	Over-temp shutdown, soft-start, output OVP (~16.5V), cycle-by-cycle current limiting
Dimensions	0.6" × 0.6" × 0.22" (15.2 × 15.2 × 5.6mm)
Weight	1.5g

Pinout & power notes

Boost-topology warning (important):

This regulator cannot fully disconnect the load from the input. When disabled (or when VIN exceeds the set output), input voltage can pass through to VOUT.
No built-in reverse-voltage protection. Consider adding a protection module if you’re on batteries.
No short-circuit protection; avoid output shorts and very large inrush loads (supercapacitors/constant-current loads beyond ratings are not recommended).

VIN / GND: connect your input supply. VIN must start at ≥2.7V and should not exceed VOUT (otherwise the higher VIN appears at the output).
VOUT: regulated 12V output (soft-start ramps up to reduce inrush).
EN: enabled by default via ~30kΩ pull-up to VIN; drive EN low (<0.4V) to disable and reduce power draw.
Low-VIN cutoff (UVLO): you can add a resistor from EN to GND to set a cutoff threshold (Pololu provides the formula).
Handling note: during normal operation it can get hot enough to burn—mount and test with care.

FAQ

Why does my output still show voltage when “disabled”?

This is normal for the boost topology used—VIN can pass through to VOUT when disabled, and VIN above the set output will also appear at VOUT.
Can I power it from 12V and still get regulated 12V?

Not recommended—VIN should not exceed VOUT. If VIN is higher than VOUT, that higher voltage will appear at the output and can be dangerous for your load.
How do I reduce voltage spikes on long power leads?

Add an electrolytic capacitor (Pololu suggests ~33µF as a starting point) close to VIN/GND to help suppress LC spikes.
Can I use this on a breadboard?

Yes, it’s 0.1" spaced, but be mindful: breadboards and header pins are usually not intended for high current. Pololu notes each header pin is rated about 3A.