MS51
Nov. 28, 2019
Page
472
of 491
Rev 1.00
MS51
32K
SE
RIES
TE
CHNICAL RE
F
EREN
CE MA
N
UAL
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Bit
Name
Description
4
POF
Power-on reset flag
This bit will be set as 1 after a power-on reset. It indicates a cold reset, a power-on reset complete.
This bit remains its value after any other resets. This flag is recommended to be cleared via
software.
nRESET Reset Waveform
7.3.1.2
The nRESET reset means to generate a reset signal by pulling low nRESET pin, which is an
asynchronous reset input pin and can be used to reset system at any time. When the nRESET voltage
is lower than 0.2 V
DD
and the state keeps longer than 32 system clock, chip will be reset. The nRESET
reset will control the chip in reset state until the nRESET voltage rises above 0.7 V
DD
and the state
keeps longer than 200 us (glitch filter). The POF will be set 1. Figure 7.3-1 nRESET Reset Waveform
shows the nRESET reset waveform.
nRESET
0.2 V
DD
0.7 V
DD
nRESET Reset
200 us
32 Fsys
Clock
Figure 7.3-1 nRESET Reset Waveform
Low Voltage Reset (LVR) Waveform
7.3.1.3
If the Low Voltage Reset function is enabled by setting the Low Voltage Reset Enable Bit LVREN
(SYS_BODCTL[7]) to 1, after 200us delay, LVR detection circuit will be stable and the LVR function
will be active. Then LVR function will detect AV
DD
during system operation. When the AV
DD
voltage is
lower than V
LVR
and the state keeps longer than De-glitch time set by LVRDGSEL
(SYS_BODCTL[14:12]), chip will be reset. The LVR reset will control the chip in reset state until the
AV
DD
voltage rises above V
LVR
and the state keeps longer than De-glitch time set by LVRDGSEL
(SYS_BODCTL[14:12]). The default setting of Low Voltage Reset is enabled without De-glitch
function. Figure 7.3-4 shows the Low Voltage Reset waveform.