Pololu Step-Down Spannungsregler D24V3ALV

Item number: PO2101

Manufacturer Part Number: 2101

The compact (0.4???0.6?) D24V3ALV switching step-down (or buck) voltage regulator takes an input voltage between 4.5?V and 42?V and efficiently reduces it to a lower, user-adjustable voltage. It has a output voltage range of 2.5?V to 7.5?V and a maximum output current of 300mA. The pins have a 0.1? spacing, making this board compatible with standard solderless breadboards and perfboards.

Category: Power supply


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Note:If you do not need the adjustable functionality of this regulator, we recommend our newer500mA D24V5Fx familyand1A D24V10Fx familyof fixed-output step-down voltage regulators over this product. They offer similar performance with much lower dropout voltages and higher efficiencies at light loads.


These adjustable buck (step-down) voltage regulators generate lower, user-adjustable output voltages from a wide input voltage range of 4.5 to 42V. They are switching regulators (also called switched-mode power supplies (SMPS) or DC-to-DC converters) and have a typical efficiency of 80%, which is much more efficient than linear voltage regulators, especially when the difference between the input and output voltage is large. The output voltage is set using the board?s trimmer potentiometer, with the two D24VxALVversions having an available range of approximately 2.5Vto7.5V and the two D24VxAHVmodels having an available range of approximately 4Vto25V. Versions with 300mA and 600mA maximum output currents are available.

The regulator has short-circuit protection, and thermal shutdown prevents damage from overheating. The board doesnot have reverse-voltage protection.


  • input voltage: 4.5V to 42V (note: the input voltage should be at least a few volts above the output voltage)
  • output adjustable from 2.5Vto7.5V (D24VxALV) or 4Vto25V (D24VxAHV)
  • maximum output current of 300mA (D24V3Axx) or 600mA (D24V6Axx)
  • 1.25MHz switching frequency
  • 2mA typical no-load quiescent current (20A typical quiescent current withSHDN= 0V)
  • integrated over-temperature and over-current shutoff
  • small size: 0.6"נ0.4"נ0.16" (15נ10נ4mm)
  • weight without header pins: 0.03oz (0.8g)

Using the Regulator


The buck regulator has four connections: shutdown (SHDN), input voltage (VIN), ground (GND), and output voltage (VOUT).

TheSHDNpin can be driven low (under 0.3V) to turn off the output and put the board into a low-power state that typically draws 20A, and it can be driven high (above 2.3V) to enable the board. If you do not need to use the shutdown feature, theSHDNpin can be directly connected to VIN to permanently enable the board.You should not leave this pin disconnectedas this can result in unpredictable behavior.

The input voltage, VIN, should be between 4.5V and 42V. If the input voltage gets too close to the output voltage, the output will start to drop, so you should ensure that VIN is at least a few volts above VOUT. You should also ensure that noise on your input does not exceed the 42V maximum, and you should be wary of destructive LC spikes (see below for more information).

The output voltage, VOUT, is determined by the trimmer potentiometer position. Setting the output voltage to be higher than the input voltage will not damage the board, but it will produce an oscillating output rather than a clean power rail (see the oscilloscope capture below), so we recommend you avoid setting the output voltage to be higher than the input voltage. The available output voltage range depends on your input voltage, VIN, and the regulator version you have: 2.5Vto7.5V (D24VxALV) or 4Vto25V (D24VxAHV). The maximum available output current also depends on your regulator version: 300mA (D24V3Axx) or 600mA (D24V6Axx). Exceeding the maximum output current can cause the output voltage to drop below its set value.

VOUT of the Pololu step-down regulator D24V3ALV when VIN is 5V and the output voltage setting is higher than 5V.

The four 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 solderlessbreadboards,connectors, and other prototyping arrangements that use a 0.1" grid. You can solder wires directly to the board or solder in either the 41straight male header stripor the 41right-angle male header stripthat is included.

Setting the output voltage

The output voltage can be measured using a multimeter. 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. When setting the output voltage, note that the buck regulator can only produce voltages lower than the input voltage.

Output voltage settings for the adjustable 2.5-7.5V and 4-25V buck regulators (D24VxAxx).

Typical Efficiency and Output Current

The efficiency of a voltage regulator, defined as (Powerout)/(Powerin), is an important measure of its performance, especially when battery life or heat are concerns. As shown in the graphs below, this switching regulator typically has an efficiency of 70% to 90%. The maximum achievable output current of the board depends on many factors, including the ambient temperature, air flow, heat sinking, and the input and output voltage. See the graphs below for more details on the typical efficiency and output currents for this voltage regulator.

Note that the achievable output current of the two 300mA D24V3Axx regulators depends on the input and output voltage, as shown in the graph below.

Typical available output current of Pololu step-down voltage regulator D24V3Axx.

LC Voltage Spikes

When connecting voltage to electronic circuits, the initial rush of current can cause voltage spikes that are much higher than the input voltage. If these spikes exceed the regulator?s maximum voltage (42V), the regulator can be destroyed. In our tests with typical power leads (~30" test clips), input voltages above 20V caused spikes over 42V. If you are connecting more than 20V or your power leads or supply has high inductance, we recommend soldering a 33F or larger electrolytic capacitor close to the regulator between VIN and GND. The capacitor should be rated for at least 50V.

More information about LC spikes can be found in our application note,Understanding Destructive LC Voltage Spikes.

Product weight: 0,00 Kg

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