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2014-07-02 - Gecko Family - d0001_Rev1.30
82
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9.3.2 Power-On Reset (POR)
The POR ensures that the EFM32G does not start up before the supply voltage V
DD
has reached
the threshold voltage VPORthr (see Device Datasheet Electrical Characteristics for details). Before the
threshold voltage is reached, the EFM32G is kept in reset state. The operation of the POR is illustrated
in Figure 9.2 (p. 82) , with the active low POWERONn reset signal. The reason for the “unknown”
region is that the corresponding supply voltage is too low for any reliable operation.
Figure 9.2. RMU Power-on Reset Operation
POWERONn
V
DD
t im e
V
Unknown
VPORt hr
9.3.3 Brown-Out Detector Reset (BOD)
The EFM32G has 2 brownout detectors, one for the unregulated 3.0 V power and one for the internal 1.8
V power. The BODs are constantly monitoring the voltages. Whenever the voltage is below the VBODthr
value (see Electrical Characteristics for details), the corresponding active low BROWNOUTn line is held
low. The BODs also include hysteresis, which prevents instability in the corresponding BROWNOUTn
line when the supply is crossing the VBODthr limit or the AVDD bods drops below decouple pin (DEC).
The operation of the BOD is illustrated in Figure 9.3 (p. 82) . The “unknown” regions are handled
by the POR module.
Figure 9.3. RMU Brown-out Detector Operation
Unknown
BROWNOUTn
V
DD
t im e
V
Unknown
VBODt hr
VBODhyst
VBODhyst
9.3.4 RESETn pin Reset
Forcing the RESETn pin low generates a reset of the EFM32G. The RESETn pin includes an on-chip pull-
up resistor, and can therefore be left unconnected if no external reset source is needed. Also connected
to the RESETn line is a filter which prevents glitches from resetting the EFM32G.
Summary of Contents for EFM32G
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