A-star 32u4 mini lv regulator – Pololu A-Star 32U4 User Manual
Page 12
A-Star 32U4 Mini LV, bottom view with
dimensions.
over-temperature protection typically kicks in after a few seconds. These currents represent the limit of the regulator’s
capability and cannot be sustained for long periods; a good estimate for the maximum continuous regulator output
current is 60% to 70% of the values shown in the graph.
4.3. A-Star 32U4 Mini LV regulator
The A-Star Mini LV can be powered from a 2.7 V to 11.8 V
external source. The input voltage is regulated to 5 V by a
TPS63061 switching step-up/step-down (buck-boost) converter
from Texas Instruments. (We also make a
based on this integrated circuit.)
The regulator’s flexibility in input voltage is especially well-suited
for battery-powered applications in which the battery voltage begins
above 5 V and drops below 5 V as the battery discharges. Without
the typical restriction on the battery voltage staying above 5 V
throughout its life, a wider range of battery types can be considered.
For example:
• A 4-cell battery holder, which might have a 6 V output with
fresh alkalines or a 4.0 V output with partially discharged NiMH
cells, can be used to power this A*.
• A disposable 9 V battery powering the board can be
discharged to under 3 V instead of cutting out at 6 V, as with
typical linear or step-down regulators.
As shown in the left graph below, the LV’s switching regulator has
an efficiency – defined as (Power out)/(Power in) – of 80% to 90%
for most combinations of input voltage and load.
The A-Star’s components, including the microcontroller and LEDs, draw 30 mA to 40 mA in typical applications.
The rest of the regulator’s achievable output current, which depends on input voltage as well as ambient conditions,
can be used to power other devices. The right graph above shows output currents at which the voltage regulator’s
over-temperature protection typically kicks in after a few seconds. These currents represent the limit of the regulator’s
capability and cannot be sustained for long periods; a good estimate for the maximum continuous regulator output
current is 60% to 70% of the values shown in the graph.
Pololu A-Star 32U4 User’s Guide
© 2001–2014 Pololu Corporation
4. A-Star 32U4 Mini
Page 12 of 30