A-star 32u4 mini ulv regulator – Pololu A-Star 32U4 User Manual
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A-Star 32U4 Mini ULV, bottom view with
dimensions.
some of the available current on the 5 V line is used by the board itself (typically about 30 mA) or used to provide
current for the GPIO pins or 3.3 V power output (see below).
3V3 power output: This pin gives access to the output of the internal 3.3 V regulator inside the ATmega32U4.
The microcontroller uses this regulated voltage for USB signaling, but up to about 50 mA is available for powering
external circuits or devices.
When the A-Star 32U4 Mini is being powered through VIN, the sum of the 5V output current, 3V3 output current,
GPIO output current, and current used by the board itself should not exceed the maximum current that the regulator
can provide; see the following sections for details about the regulator on each version.
4.2. A-Star 32U4 Mini ULV regulator
The A-Star Mini ULV can be powered from a 0.5 V to 5.5 V
external source. The input voltage is regulated to 5 V by a
TPS61202 switching step-up (boost) converter from Texas
Instruments.
(We
also
make
a
based on this integrated circuit.)
The regulator’s low minimum input voltage makes it possible to
power this A* with 1 to 3 NiMH, NiCd, or alkaline cells or from a
single lithium cell. Unlike standard boost regulators, the TPS61202
also features a linear down-regulation mode that is automatically
enabled when the input voltage exceeds 5 V, allowing it to handle
input voltages as high as 5.5 V.
As shown in the left graph below, the ULV’s switching regulator has
an efficiency – defined as (Power out)/(Power in) – of 70% 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
Pololu A-Star 32U4 User’s Guide
© 2001–2014 Pololu Corporation
4. A-Star 32U4 Mini
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