Step-Down Schaltregler von Pololu.
Eingangsspannung: 7 - 38V
Ausgangsstrom bis zu 2,5A
The D24V25Fx family of step-down voltage regulators generates lower
output voltages from input voltages as high as 38 V. They are switching
regulators (also called switched-mode power supplies (SMPS) or DC-to-DC
converters) with typical efficiencies between 85% and 95%, which is much
more efficient than linear voltage regulators, especially when the
difference between the input and output voltage is large. The available
output current is a function of the input voltage and efficiency (see
the Typical Efficiency and Output Current section below), but the output
current can typically be as high as 2.5 A.
At light loads, the
switching frequency automatically changes to maintain high efficiencies.
These regulators have a typical quiescent (no load) current draw of
less than 1 mA, and the ENABLE pin can be used to put the boards in a
low-power state that reduces the quiescent current to approximately 10
µA to 20 µA per volt on VIN.
The modules have built-in
reverse-voltage protection, short-circuit protection, a thermal shutdown
feature that helps prevent damage from overheating, a soft-start
feature that reduces inrush current, and an under-voltage lockout.
different voltage versions of this regulator all look very similar, so
you should consider adding your own distinguishing marks or labels if
you will be working simultaneously with multiple versions. This product
page applies to all versions of the D24V25Fx family.
higher-power applications, we carry a slightly larger, pin-compatible, 5
V version of this regulator that has a typical maximum output current
of 5 A.
Two even larger, higher-power, 5 V versions of this
regulator are also available: one with a typical maximum output current
of 6 A, and the other with a typical maximum output current of 9 A. The
higher-power versions also have a few additional features, like a “power
good” signal and the ability to lower their output voltage, and they
include optional terminal blocks for easy removable connections.Features
- Input voltage:
- 4.5 V to 38 V for the version that outputs 3.3 V
- [output voltage + dropout voltage] to 38 V for output voltages of 5 V
and higher (see below for more information on dropout voltage)
- Fixed 3.3 V, 5 V, 6 V, 7.5 V, or 9 V output (depending on regulator version) with 4% accuracy
- Typical maximum continuous output current: 2.5 A
Integrated reverse-voltage protection, over-current protection,
over-temperature shutoff, soft-start, and under-voltage lockout
Typical efficiency of 85% to 95%, depending on input voltage and load;
the switching frequency automatically changes at light loads to maintain
- Typical no-load quiescent current under 1 mA; can be reduced to 10 µA to 20 µA per volt on VIN by disabling the board
- Compact size: 0.7″ × 0.7″ × 0.35″ (17.8 mm × 17.8 mm × 8.8 mm)
- Two 0.086″ mounting holes for #2 or M2 screws
Using the regulator
buck regulator has five connection points for four different
connections: enable (EN), input voltage (VIN), 2x ground (GND), and
output voltage (VOUT).
The input voltage, VIN, powers the
regulator. Voltages between 4.5 V and 38 V can be applied to VIN, but
for versions of the regulator that have an output voltage higher than
4.5 V, 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).
output voltage, VOUT, is fixed and depends on the regulator version:
the D24V25F3 version outputs 3.3 V, the D24V25F5 version outputs 5 V,
the D24V25F6 version outputs 6 V, the D24V25F7 version outputs 7.5 V,
and the D24V5F9 version outputs 9 V.
The regulator is enabled by
default: a 100 kΩ pull-up resistor on the board connects the ENABLE pin
to reverse-protected VIN. The ENABLE pin can be driven low (under 0.6 V)
to put the board into a low-power state. The quiescent current draw in
this sleep mode is dominated by the current in the pull-up resistor from
ENABLE to VIN and by the reverse-voltage protection circuit, which will
draw between 10 µA and 20 µA per volt on VIN when ENABLE is held low.
If you do not need this feature, you should leave the ENABLE pin
The five connection points are labeled on the top
of the PCB and are arranged with a 0.1″ spacing for compatibility with
solderless breadboards, connectors, and other prototyping arrangements
that use a 0.1″ grid. Either the included 5×1 straight male header strip
or the 5×1 right angle male header strip can be soldered into these
holes. For the most compact installation, you can solder wires directly
to the board.
The board has two 0.086″ mounting holes intended
for #2 or M2 screws. The mounting holes are at opposite corners of the
board and are separated by 0.53″ both horizontally and vertically.
Typical efficiency and output current
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. This family of switching regulators typically has
an efficiency of 85% to 95%, though the actual efficiency in a given
system depends on input voltage, output voltage, and output current. See
the efficiency graph near the bottom of this page for more information.
maximum achievable output current is typically around 2.5 A, but this
depends on many factors, including the ambient temperature, air flow,
heat sinking, and the input and output voltage.
Typical dropout voltage
dropout voltage of a step-down regulator is the minimum amount by which
the input voltage must exceed the regulator’s target output voltage in
order to ensure the target output can be achieved. For example, if a 5 V
regulator has a 1 V dropout voltage, the input must be at least 6 V to
ensure the output is the full 5 V. Generally speaking, the dropout
voltage increases as the output current increases. See the “Details”
section below for more information on the dropout voltage for this
specific regulator version.
Switching frequency and behavior under light loads
regulator generally operates at a switching frequency of around 600
kHz, but the frequency drops when encountering a light load to improve
efficiency. This could make it harder to filter out noise on the output
caused by switching.