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.Features
- Input voltage: 6V to 42 V
- Fixed 5 V output with 4% accuracy
- Maximum output current: 600 mA
- 1.25 MHz switching frequency
- 2 mA typical no-load quiescent current (20 μA 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)
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 μA, 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 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 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 4×1 straight male header strip or the 4×1 right-angle male header strip that is included.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 (42 V), the regulator can be destroyed. In our tests with typical power leads (~30″ test clips), input voltages above 20 V caused spikes over 42 V. If you are connecting more than 20 V or your power leads or supply has high inductance, we recommend soldering a 33μF or larger electrolytic capacitor close to the regulator between VIN and GND. The capacitor should be rated for at least 50 V.
More information about LC spikes can be found in our application note, Understanding Destructive LC Voltage Spikes.