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Pololu 5V 500mA Step-Down (Buck) Voltage Regulator D45V5F5 

Need a clean 5V rail from a high-voltage supply? D45V5F5 is a tiny synchronous buck (step-down) regulator that converts inputs up to 65V down to a fixed 5V output (±4%). It’s designed for efficient power conversion in compact builds—especially when the input-to-output difference is large (where linear regulators waste heat). 

  • Wide input range: 5.2V to 65V (minimum VIN depends on dropout and load). 
  • High efficiency switching regulator: far less heat vs. linear regulators for big step-downs. 
  • Low idle draw: quiescent current is typically <0.2mA for most of the operating range. 
  • Protection built-in: short-circuit and over-temperature protection. 
  • Compact: 0.3″ × 0.45″ × 0.11″ (7.6 × 11.4 × 2.8mm), ~0.4g. 
  • 3-pin, 0.1" spacing: VIN / GND / VOUT along the edge for breadboards and 0.1" systems.

*Minimum VIN is subject to dropout voltage; VIN typically needs to be above VOUT by the regulator’s dropout amount at your load. 

Important (please read):
  • Watch for LC voltage spikes: long power leads + inrush can create spikes that approach/exceed the 65V max and damage the board. Pololu recommends adding an electrolytic capacitor ( 33µF is a good starting point ) close to VIN–GND.
  • No reverse-voltage protection on-board: add an external reverse-voltage protection module if polarity mistakes are possible. 
  • Current depends on thermals: maximum continuous output current varies with VIN, airflow, and ambient temperature (Pololu provides graphs). 

Why/Benefits

Efficient 5V from high voltage
  • Ideal for stepping down from 12V/24V/48V systems to 5V logic rails
  • Much lower heat vs linear regulators for large voltage drops 
  • Fixed switching frequency at normal loads; reduces frequency at light loads for better efficiency.
Prototype-friendly
  • 0.1" pin spacing for breadboards and perfboards 
  • Only 3 connections (VIN/GND/VOUT) for quick wiring 
  • Short-circuit + thermal protection for extra peace of mind 

Technical specifications

Product Pololu 5V, 500mA Step-Down Voltage Regulator D45V5F5 
Topology Synchronous buck (step-down) switching regulator
Output voltage 5V (±4% accuracy)
Input voltage 5.2V to 65V (minimum subject to dropout vs load)
Typical max output current 500mA (varies; see thermal/current graphs)
Max output current (peak/graph) Up to 700mA (thermal dependent)
Switching frequency 1.1MHz at normal loads (reduced at light loads)
Quiescent current < 0.2mA for most of operating range
Protections Short-circuit protection, over-temperature protection
Connections VIN, GND, VOUT (0.1" spacing)
Size 0.3″ × 0.45″ × 0.11″ (7.6 × 11.4 × 2.8mm)
Weight 0.4g

Pinout & power notes

  • VIN: input power (up to 65V). Keep leads short and consider an electrolytic capacitor near VIN–GND to reduce LC spikes. 
  • GND: common ground.
  • VOUT: regulated 5V output.
  • Dropout note: VIN must be above VOUT by the dropout voltage, which increases with load (see Pololu dropout graphs). 

FAQ

  • Can I use this from 12V or 24V?
    Yes. It’s designed to step down higher voltages to 5V efficiently (VIN up to 65V). Add a nearby electrolytic capacitor if you have long leads. 
  • Why does the minimum input say “subject to dropout”?
    As load current increases, the regulator needs a bit more headroom above 5V to maintain regulation. Pololu provides dropout graphs vs load. 
  • Does it have reverse polarity protection?
    No—use an external reverse-voltage protection module if needed. 

5V, 500mA Step-Down Voltage Regulator D45V5F5

5V, 500mA Step-Down Voltage Regulator D45V5F5

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Product Code

POL5433

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