...the world's most energy friendly microcontrollers
2012-05-31 - t0014_0.11
5
www.energymicro.com
4 Power Supply and Reset
4.1 MCU Power Selection
The EFM32 Giant Gecko MCU on the EFM32GG-STK3700 is designed to be powered by three different
sources:
• Through the on-board debugger.
• Through the EFM32's own USB regulator.
• By a 3V Battery.
Selecting the power source is done with the slide switch in the lower left corner of the board. Figure
Figure 4.1 (p. 5) shows how the different power sources can be selected with the slide switch.
Figure 4.1. EFM32GG-STK3700 Power Switch
3.3V
VMCU
DBG
USB
BAT
USB Mini-B
Connect or
Advanced
Energy
Monit or
5V
3V Lit hium Bat t ery
(CR2032)
EFM32 Giant
Gecko MCU
USB OTG
Connect or
USB_VREGI
(5V)
USB_VREGO
(3.3V)
B
A
T
U
SB
D
B
G
With the switch in the DBG position, an on-board low noise LDO with a fixed output voltage of 3.3V
is used to power the MCU. This LDO is again powered from the "J-Link" USB cable. The Advanced
Energy Monitor is now also connected in series, allowing accurate high speed current measurements
and energy debugging/profiling.
With the switch in the USB position, the integrated linear regulator in the EFM32 Giant Gecko MCU is
used to power the rest of the chip as well as the USB PHY. This allows a USB device application where
the MCU acts as a bus powered device.
Finally, with the switch in the BAT position, a 20mm coin cell battery in the CR2032 socket can be used
to power the device.
Note
The Advanced Energy Monitor can only measure the current consumption of the EFM32
when the power selection switch is in the DBG position.
4.2 Board Controller Power
The Board Controller is responsible for important features such as the debugger and the Advanced
Energy Monitor, and is powered exclusively through the USB port in the top left corner of the board.
This part of the kit resides on a separate power domain, so a different power source can be selected for
the MCU while retaining debugging functionality. This power domain is also isolated to prevent current
leakage from the MCU power domain when power to the Board Controller is removed.
Summary of Contents for EFM32 Giant Gecko Starter Kit
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