The compact (0.5? × 0.7?) D24V10F9 synchronous buck voltage regulator takes an input voltage of up to 36 V and efficiently reduces it to 9 V while allowing for a maximum output current of 1 A. This regulator offers typical efficiencies between 85% and 93% and has a very low dropout, so it can be used with input voltages as low as a few hundred millivolts above 9 V. The pins have a 0.1? spacing, making this board compatible with standard solderless breadboards and perfboards.
These buck (step-down) voltage regulators generate lower output voltages from input voltages as high as 42 V. They are switching regulators (also called switched-mode power supplies (SMPS) or DC-to-DC converters) and have a typical efficiency between 80% to 90%, which is much more efficient than linear voltage regulators, especially when the difference between the input and output voltage is large.
The regulator has short-circuit protection, and thermal shutdown prevents damage from overheating. The board does not have reverse-voltage protection.
Using the Regulator
The buck regulator has four connections: shutdown (SHDN), input voltage (VIN), ground (GND), and output voltage (VOUT).
The SHDN pin can be driven low (under 0.3 V) to turn off the output and put the board into a low-power state that typically draws 20 ?A. The SHDN pin can be driven high (above 2.3 V) to enable the board, or it can be connected to VIN or left disconnected if you want to leave the board permanently enabled.
The input voltage, VIN, should exceed VOUT by at least the regulator’s dropout voltage (see below for graphs of dropout voltages as a function of the load), and you must ensure that noise on your input does not exceed the 42 V maximum. Additionally, please be wary of destructive LC spikes (see below for more information).
The output voltage, VOUT, is fixed and depends on the regulator version: the D24VxF3 version outputs 3.3 V, the D24VxF5 version outputs 5 V, the D24VxF9 version outputs 9 V, and the D24VxF12 version outputs 12 V.
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 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 4×1 straight male header strip or the 4×1 right-angle male header strip that is included.
Typical Efficiency and Output Current
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. As shown in the graphs below, this switching regulator typically has an efficiency of 80% to 90%.