Pololu 9V, 600mA Step-Down Voltage Regulator D24V6F9 Pololu step-down voltage regulator D24VxFx next to a 7805 voltage regulator in TO-220 package. Overview 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. This regulator is available with a fixed 3.3 V, 5 V, 9 V, or 12 V output, and two versions are available for each voltage, one with a 300 mA maximum output current (D24V3Fx) and one with a 600 mA maximum output current (D24V6Fx): We also offer versions of this regulator with a user-adjustable output voltage: The regulator has short-circuit protection, and thermal shutdown prevents damage from overheating. The board does not have reverse-voltage protection. As alternatives, you might consider our newer 500 mA D24V5Fx buck regulators, which offer similar performance with much lower dropout voltages and higher efficiencies are very light loads. If you need more output current, consider our D15V35F5S3 and D15V70F5S3 3.3V/5V step-down voltage regulators, which can typically deliver a continuous 3.5 A and 7 A, respectively. Features Input voltage: output voltage + dropout voltage to 42 V (see below for more information on dropout voltage) Fixed 3.3 V, 5 V, 9 V, or 12 V output (depending on regulator version) with 4%accuracy Maximum output current: 300 mA or 600 mA (depending on regulator version) 1.25 MHz switching frequency 2 mA typical no-load quiescent current (20 A typical quiescent current with SHDN = LOW) Integrated over-temperature and over-current shutoff Small size: 0.5 0.4 0.1 (13 mm 10 mm 3 mm) Using the Regulator Connections 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, and it can be driven high (above 2.3 V) to enable the board. If you do not need to use the shutdown feature, the SHDN pin can be directly connected to VIN to permanently enable the board. You should not leave this pin disconnected as this can result in unpredictable behavior. The input voltage, VIN, should exceed VOUT by at least the regulators 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