5V Step-Up/Step-Down Voltage Regulator S9V11F5

Product Code: 2124
by Pololu
£5.41 inc VAT
£4.51 ex VAT
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The 5V switching step-up/step-down voltage regulator S9V11F5 efficiently produces 5 V from input voltages between 2 V and 16 V. (Note: it requires an input voltage of at least 3 V to start, but it can operate down to 2 V after startup.) Its ability to convert both higher and lower input voltages makes it useful for applications where the power supply voltage can vary greatly, as with batteries that start above but discharge below 5 V. The very compact (0.3"- 0.45") module has a typical efficiency of over 90% and can supply a typical output current of up to 1.5 A when the input voltage is around 5 V.

The flexibility in input voltage offered by this regulator is especially well-suited for battery-powered applications in which the battery voltage begins above 5 V and drops below as the battery discharges. Without the typical restriction on the battery voltage staying above the required voltage throughout its life, new battery packs and form factors can be considered. For instance, a 4-cell battery holder, which might have a 6 V output with fresh alkalines but a 4.8 V nominal voltage with NiMH cells and a 4.0 V output with partially discharged cells, can now be used for a 5 V circuit. In another typical scenario, a disposable 9V battery powering a 5 V circuit can be discharged to under 3 V instead of cutting out at 6 V, as with typical linear or step-down regulators.

Note: The regulator has short-circuit protection,  the board does not have reverse-voltage protection.

Important: During normal operation, this product can get hot enough to burn you. Take care when handling this product or other components connected to it.

  • Input voltage: 2 V to 16 V (note: this regulator requires 3 V to start, but it can operate down to 2 V after startup)
  • Fixed 5 V output with +5/-3% accuracy
  • Typical maximum continuous output current: 1.5 A (when input voltage is around 5 V; the Typical Efficiency and Output Current section below shows how the achievable continuous output current depends on the input voltage)
  • Power-saving feature maintains high efficiency at low currents (quiescent current is less than 0.2 mA)
  • Integrated over-temperature and short-circuit protection


  • Size: 0.3"- 0.45"- 0.15"
  • Weight: 0.5 g (Without included optional headers)
  • Minimum operating voltage: 2 V (Note: the minimum startup voltage is 3V, but the regulator can operate down to 2V after startup)
  • Maximum operating voltage: 16 V
  • Maximum output current: 1.5 A (Under typical conditions, where the input voltage is close to the output voltage. Maximum output current can be higher when stepping down and lower when stepping up)
  • Output voltage: 5 V
  • Maximum quiescent current: 0.2 mA (With no load. Actual quiescent current depends on input voltage; it is typically under 100 µA for input voltages less than 7 V)
  • No reverse voltage protection


The step-up/step-down regulator has just three connections: the input voltage (VIN), ground (GND), and the output voltage (VOUT). These through-holes are arranged with a 0." spacing along the edge of the board for compatibility with standard solderless breadboards and perfboards and connectors that use a 0." grid. You can solder wires directly to the board or solder in either the 3x1 straight male header strip or the 3x1 right-angle male header strip that is included. VOUT is labelled on the silkscreen on one side of the board, and GND is in the middle and can be identified by its square pad.

The input voltage, VIN, should be between 3 V and 16 V when the regulator is first powered. After it is running, it can continue operating down to 2 V. Lower inputs can shut down the voltage regulator; higher inputs can destroy the regulator, so you should ensure that noise on your input is not excessive, and you should be wary of destructive LC spikes. The output voltage, VOUT, is regulated to a fixed 5 V, but it can be as high as 5.2 V when there is little or no load on the regulator.

Typical Efficiency:

The efficiency of a voltage regulator, defined as (Power out)/(Power in), is an important measure of its performance, especially when battery life or heat are concerns. This switching regulator typically has an efficiency of 85% to 95%. A power-saving feature maintains these high levels of efficiency even when the regulator current is very low.

LC Voltage Spikes:

When connecting voltage to electronic circuits, the initial current can cause voltage spikes that are much higher than the input voltage. If you are connecting more than 12 V or using a power supply with high inductance, we recommend soldering a < 33 uF electrolytic capacitor between VIN and GND. The capacitor should be rated for at least 20V.

Understanding Destructive LC Voltage Spikes