AT32F421
Series Reference Manual
2022.11.11
Page 40
Rev 2.02
3.3 POR/LVR
A POR analog module embedded in the VDD/VDDA domain is used to generate a power reset. The
power reset signal is released at V
POR
when the VDD is increased from 0 V to the operating voltage, or
it is triggered at V
LVR
when the VDD drops from the operating voltage to 0 V. During the power-on reset
period, the reset signal release has certain amount of time delay compared to VDD boost process. At
the same time, hysteresis occurs in power-on reset (POR) and low voltage reset (LVR).
Figure 3-2 Power-on reset/Low voltage reset waveform
Reset
VDD
V
LVR
V
POR
Temporization
tRESTTEMPO
(V
POR
-V
LVR
)
hysteresis
3.4 Power voltage monitor (PVM)
The PVM is used to monitor the power supply variations. It is enabled by setting the PVMEN bit in the
power control register (PWC_CTRL), and the threshold value for voltage monitor is selected with the
PVMSEL[2: 0] bit.
After PVM is enabled, the comparison result between VDD and the programmed threshold is indicated
by the PVMOF bit in the PWC_CTRLSTS register, with the hysteresis voltage VHYS_P being 100 mv.
The PVM interrupt will be generated (due to PVMOF level change ) through the EXTI line 16 when VDD
rises above the PVM threshold.