Power Supply And Reset; Radio Board Power Selection - Silicon Laboratories SLWRB4150A User Manual

5. Power Supply and Reset

5.1 Radio Board Power Selection

The EFR32 on a Wireless Starter Kit can be powered by one of these sources:
• the debug USB cable;
• a 3V coin cell battery; or
• a USB regulator on the Radio Board (for devices with USB support only).
The power source for the radio board is selected with the slide switch in the lower left corner of the Wireless STK Mainboard.
5.1 Power Switch on page 9 shows how the different power sources can be selected with the slide switch.
5 V
USB Mini-B
Connector
3 V Lithium Battery
(CR2032)
With the switch in the AEM position, a low noise 3.3 V LDO on the WSTK Mainboard is used to power the Radio Board. This LDO is
again powered from the debug 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, radio boards with USB-support can be powered by a regulator on the radio board itself. BRD4150A
does not contain an USB regulator, and setting the switch in the USB postition will cause the EFR32 to be unpowered.
Finally, with the switch in the BAT position, a 20 mm coin cell battery in the CR2032 socket can be used to power the device. With the
switch in this position no current measurements are active. This is the recommended switch position when powering the radio board
with an external power source.
Note: The current sourcing capabilities of a coin cell battery might be too low to supply certain wireless applications.
Note: The Advanced Energy Monitor can only measure the current consumption of the EFR32 when the power selection switch is in
the AEM position.
silabs.com | Smart. Connected. Energy-friendly.
Advanced
3.3 V
LDO Energy
Monitor
Figure 5.1. Power Switch
UG178: EFR32MG 2400/868 MHz 13 dBm Dual Band Radio Board
AEM
VMCU
USB
BAT
Power Supply and Reset
Figure
EFR32
Rev. 1.00 | 9