9.3.4.3 Power Configuration 2: DC-DC
For the lowest power applications, the DC-DC converter can be used to power the DVDD supply.
In Power Configuration 2, the DC-DC Output (V
DCDC
) is connected to DVDD. DVDD powers the internal Digital LDO which powers the
digital circuits. AVDD is connected to the main supply voltage. The internal analog blocks may be powered from AVDD or DVDD, de-
pending on the ANASW configuration. IOVDD could be connected to either the main supply (as shown below) or to V
DCDC
, depending
on the system IO requirements.
DECOUPLE
DVDD
AVDD_0
VREGSW
Main
Supply
VREGVSS
IOVDD
ANASW
Analog
Blocks
DC-DC
DC-DC
Driver
Bypass
Switch
VREGVDD
OFF
0
1
V
DCDC
Digital
LDO
Digital
Logic
FLASH
+
–
V
DD
AVDD_1
As the Main Supply voltage approaches the DC-DC output voltage, it eventually reaches a point where becomes inefficient (or impossi-
ble) for the DC-DC module to regulate V
DCDC
. At this point, the system can be dynamically switched into DC-DC bypass mode, which
effectively disables the DC-DC and shorts the Main Supply voltage directly to the DC-DC output. If and when sufficient voltage margin
on the Main Supply returns, the system can be switched back into DC-DC regulation mode.
9.3.5 DC-to-DC Interface
The EFM32 Jade Gecko features a DC-to-DC buck converter which requires a single external inductor and a single external capacitor.
The converter takes the VREGVDD input voltage and converts it down to an output voltage between VREGVDD and 1.8 V with a peak
efficiency of approximately 90% in Low Noise (LN) mode and 85% in Low Power (LP) mode. Refer to datasheet for full DC-DC specifi-
cations.
The DC-DC converter operates in either Low Noise (LN) or Low Power (LP) mode. LN mode is intended for higher current operation
(e.g., EM0), whereas LP mode is intended for very low current operation (e.g., EM2 and below). The DC-DC may be configured to auto-
matically transition from LN mode in EM0/EM1 to LP mode in EM2, EM3, or EM4.
In addition, the DC-DC converter supports an unregulated Bypass mode, in which the input voltage is directly shorted to the DC-DC
output.
EFM32JG1 Reference Manual
EMU - Energy Management Unit
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