Perfect for running the new Spektrum VA2500 FPV Cam/VTX off a 1s Lipo
Overview
This 5 V boost (step-up) voltage regulator generates higher output
voltages from input voltages as low as 0.5 V, and it also automatically
switches to a linear down-regulation mode when the input voltage exceeds
the output. This makes it great for powering 5 V electronics projects
from 1 to 3 NiMH, NiCd, or alkaline cells or from a single lithium-ion
cell.
When boosting, this module acts as a switching regulator (also called
switched-mode power supplies (SMPS) or DC-to-DC converters) and has a
typical efficiency between 70% to 90%. The available output current is a
function of the input voltage, output voltage, and efficiency (see Typical Efficiency and Output Current section below), but the input current can typically be as high as 1.2 A.
The regulator’s thermal shutdown engages at around 140°C and helps prevent damage from overheating, but it does not have short-circuit or reverse-voltage protection.
Features
- Input voltage: 0.5 V to 5.5 V
- Fixed 5 V output with 4% accuracy
- Automatic linear down-regulation when the input voltage is greater than the output voltage
- 1.2 A switch allows for input currents up to 1.2 A
- Good efficiency at light load: <1 mA typical no-load quiescent current, though it can exceed 1 mA for very low input voltages
- Integrated over-temperature shutoff
- Small size: 0.35? × 0.45?; × 0.1? (9 × 11.5 × 2.5 mm)
Using the Regulator
Connections
The boost regulator has three connections: input voltage (VIN), ground (GND), and output voltage (VOUT).
The input voltage, VIN, must be at least 0.5 V for the regulator to
turn on. However, once the regulator is on, the input voltage can drop
as low as 0.3 V and the 5 V output voltage will be maintained on VOUT.
Unlike standard boost regulators, this regulator has an additional
linear down-regulation mode that allows it to convert input voltages as
high as 5.5 V down to 5 V for small to moderate sized loads. When the
input voltage exceeds 5 V, the regulator automatically switches to this
down-regulation mode. The input voltage should not exceed 5.5 V. Please
be wary of destructive LC spikes that might cause the input voltage to
surpass 5.5 V (see below for more information).
The three 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 3×1 straight male header strip or the 3×1 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 70
to 90%.
The maximum achievable output current is approximately
proportional to the ratio of the input voltage to the output voltage.
If the input current exceeds the switch current limit
(typically somewhere between 1.2 and 1.5 A), the output voltage will
begin to drop. Additionally, the maximum output current can depend on
other factors, including the ambient temperature, air flow, and heat
sinking.
LC Voltage Spikes
When connecting voltage to electronic circuits, the initial rush of
current can cause damaging voltage spikes that are much higher than the
input voltage. In our tests with typical power leads (~30? test clips),
input voltages above 4.5 V caused voltage spikes that could potentially
damage the regulator. You can suppress such spikes by soldering a 33 µF
or larger electrolytic capacitor close to the regulator between VIN and
GND.
Dimensions
Size:
|
0.35? × 0.45? × 0.1?
|
Weight:
|
0.4 g
|
General specifications
Minimum operating voltage:
|
0.5 V
|
Maximum operating voltage:
|
5.5 V
|
Maximum input current:
|
1.2 A2
|
Output voltage:
|
5 V
|
Reverse voltage protection?:
|
N
|
Maximum quiescent current:
|
1 mA3
|
Identifying markings
PCB dev codes:
|
reg12b
|
Other PCB markings:
|
0J7517
|
Notes:
- Without included optional headers.
- Regulator
may overheat at lower input currents when VIN is much lower than VOUT.
Available output current is a function of VIN, VOUT, and the regulator
efficiency.
- The highest quiescent
currents occur at very low input voltages; for most of the input voltage
range, the quiescent current is well below 1 mA.