This powerful, adjustable boost regulator can generate an output voltage as high as 9.5 V from an input voltage as low as 1.5 V, all in a tiny, 10.7mm x 22.4mm x 5.8mm package. A trimmer potentiometer lets you set the boost regulator’s output voltage to a value between 2.5 and 9.5 V.
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Our Code: MCU-60026
Supplier Link: [Pololu MPN:791]
The Pololu adjustable boost regulator is a very flexible switching regulator (also called a switched-mode power supply, SMPS, or DC-to-DC converter) that can generate voltages higher than its input voltage. The output voltage of 2.5 V to 9.5 V can be set using the trimmer potentiometer in the upper-right corner of the board. The input voltage range is 1.5 V to 16 V (the input voltage should be kept below the output voltage). The integrated 2 A switch allows for output currents high enough to drive small motors, as in our 3pi robot, and allows large voltage gains, such as obtaining 9.5V from two NiMH or NiCd cells.
Some example applications include:
The boost regulator has just three connections: the input voltage, ground, and the output voltage. These three connections are labeled on the back side of the PCB, and they are arranged with a 0.1" spacing along the edge of the board for compatibility with solderless breadboards, connectors, and other prototyping arrangements that use a 0.1" grid. You can solder wires directly to the board or solder in either the 3×1 straight male header strip or the 3×1 right-angle male header strip that is included.
The output voltage can be adjusted using a meter and a light load (e.g. a 1k resistor). Turning the potentiometer clockwise increases the output voltage. The output voltage can be affected by a screwdriver touching the potentiometer, so the output measurement should be done with nothing touching the potentiometer. The potentiometer has no physical end stops, which means that the wiper can be turned 360 degrees and into an invalid region in which the output voltage is set to approximately 2.5 V (for both the 2.5 V to 9.5 V and 4 V to 25 V versions). The input voltage should not exceed the output voltage, so we recommend setting the output voltage with the input voltage set to around 2.5 V.
The chart below shows the output voltages for both the 2.5-9.5V and 4-25V versions of this regulator.
Output voltage settings for the adjustable boost regulators.
The absolute limit for the input voltage is double the output set voltage. For example, if the output is set to 6 V, the input must not exceed 12 V. Once the input exceeds the output set point, the output voltage will rise with the input voltage since the input is connected to the output through an inductor and a diode.
Note: The trimmer potentiometer is not rated for continual adjustment back and forth; the intended application is to set the output voltage a few times in its life.
The available output current depends on the input and output voltages. The input current is limited to approximately 2 A, and the efficiency is typically 80%. Therefore, the maximum available current will be approximately 800 mA when doubling the input voltage and approximately 400 mA when quadrupling the input voltage. At high output powers, the 20% lost in the regulator will cause substantial heating, which can limit the available output power (the regulator will automatically shut off if its internal temperature gets too high). At low output currents and high input and output voltages, the efficiency drops closer to 50%, though the lower power involved prevents heating from being an issue.