Power Supply And Reset; Radio Board Power Selection; Board Controller Power - Silicon Laboratories SLWSTK6104A User Manual

4. Power Supply and Reset

4.1 Radio Board Power Selection

The MGM220P on a Wireless Starter Kit can be powered by one of these sources:
• The debug USB cable
• A 3 V coin cell battery
• 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. The figure
below shows how the different power sources can be selected with the slide switch.
5 V
USB Mini-B
Connector
3 V Lithium Battery
With the switch in the AEM position, a low noise 3.3 V LDO on the mainboard is used to power the radio board. This LDO is again
powered from the debug USB cable. The AEM 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. BRD4311B
does not contain a USB regulator, and setting the switch in the USB position will cause the MGM220P 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 AEM can only measure the current consumption of the MGM220P when the power selection switch is in the AEM position.

4.2 Board Controller Power

The board controller is responsible for important features, such as the debugger and the AEM, 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 target device while retaining debugging functionality. This power domain is also isolated to prevent current leakage
from the target power domain when power to the board controller is removed.
The board controller power domain is not influenced by the position of the power switch.
The kit has been carefully designed to keep the board controller and the target power domains isolated from each other as one of them
powers down. This ensures that the target MGM220P device will continue to operate in the USB and BAT modes.
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Advanced
3.3 V
Energy
LDO
Monitor
(CR2032)
Figure 4.1. Power Switch
UG461: MGM220P Wireless Gecko Module Starter Kit User's Guide
AEM
VMCU
USB
BAT
Power Supply and Reset
MGM220P
Rev. 1.0 | 14