Pololu 5V, 1A Step-Down Voltage Regulator D24V10F5

Overview

The D24V10Fx family of step-down voltage regulators features the Intersil ISL85410 1A synchronous buck regulator and generates lower output voltages from input voltages as high as 36 V. They are switching regulators (also called switched-mode power supplies (SMPS) or DC-to-DC converters) with typical efficiencies between 80% and 95%, which is much more efficient than linear voltage regulators, especially when the difference between the input and output voltage is large. These regulators have a power-save mode that activates at light loads and a low quiescent (no load) current draw, which make them well suited for applications that are run from a battery.

The different versions of this regulator all look very similar, so the bottom silkscreen includes a blank space where you can add your own distinguishing marks or labels. This product page applies to all five versions of the D24V10Fx family.

The SHDN pin can be used to put the board in a low-power state that reduces the quiescent current to approximately 10 µA to 20 µA per volt on VIN, and a PG (power good) output can be used to monitor the state of the regulator’s output voltage.

The regulators feature short-circuit/over-current protection, and thermal shutdown helps prevent damage from overheating. The boards do not have reverse-voltage protection.

The picture on the right shows a 1 A D24V10Fx regulator next to a 0.5 A D24V5Fx regulator and a common 7805 linear regulator in a TO-220 package.

Pololu step-down voltage regulators D24V10Fx and D24V5Fx next to a 7805 voltage regulator in TO-220 package.

Using the regulator

Connections

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

The "power good" indicator, PG, is an open-drain output that drives low when the regulator’s output voltage falls below 80% or rises above 120% of its target output voltage. This output is also actively held low for the duration of the regulator’s 2 ms soft-start period and while the regulator is being disabled by the SHDN input or by over-temperature or over-current fault conditions. An external pull-up resistor is generally required to use this pin.

The SHDN pin can be driven low (under 0.4 V) to turn off the output and put the board into a low-power state. There is a 100 kΩ pull-up resistor between the SHDN pin and VIN, so if you want to leave the board permanently enabled, the SHDN pin can be left disconnected. While the SHDN pin is being driven low, the current draw of the regulator is dominated by the current through the pull-up resistor and will be proportional to the input voltage. (At 36 V in it will draw about 360 μA.)

The input voltage, VIN, powers the regulator. Voltages between 3 V and 36 V can be applied to VIN, but the effective lower limit of VIN is VOUT plus the regulator’s dropout voltage, which varies approximately linearly with the load (see below for graphs of dropout voltages as a function of the load). 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 D24V10F3 version outputs 3.3 V, the D24V10F5 version outputs 5 V, the D24V10F6 version outputs 6 V, the D24V10F9 version outputs 9 V, and the D24V10F12 version outputs 12 V.

The five connections are labeled on the back side of the PCB and 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 5x1 straight male header strip or the 5x1 right-angle male header strip.

Schematic diagram for the Pololu D24V10Fx family of 1 A step-down voltage regulators.