Power-On Reset (Por); Brown-Out Detector (Bod) - Silicon Laboratories EFR32xG14 Wireless Gecko Reference Manual

Reference Manual
RMU - Reset Management Unit

9.3.3 Power-On Reset (POR)

The POR ensures that the EFR32 does not start up before the AVDD supply voltage has reached the threshold voltage VPORthr
(roughly 1.2V). Before the POR threshold voltage is reached, the EFR32 is kept in reset state. The operation of the POR is illustrated in
Figure 9.2 RMU Power-on Reset Operation on page 203, 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.
V
V
DD
VPORthr
POWERONn
Unknown
time
Figure 9.2. RMU Power-on Reset Operation

9.3.4 Brown-Out Detector (BOD)

The EFR32 has 3 brownout detectors, one for the unregulated power (DVDD), one for the regulated internal power (DECOUPLE), and
one for the Analog Power Domain (AVDD). The BODs are constantly monitoring these supply voltages. Whenever the unregulated or
regulated power drops below the VBODthr value (see the Electrical Characteristics section of the data sheet for details), or if AVDD
drops below the voltage at the DECOUPLE pin, 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 supply drops below the DECOUPLE pin. The operation of the BOD is illustrated in Figure 9.3 RMU Brown-out Detector Opera-
tion on page 203. The "unknown" regions are handled by the POR module.
V
VBODhyst
VBODthr
VBODhyst
V
DD
BROWNOUTn
Unknown Unknown
time
Figure 9.3. RMU Brown-out Detector Operation
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