STM32W108HB Datasheet, PDF (159/179 Pages) STMicroelectronics – High-performance, IEEE 802.15.4 wireless system-on-chip

STM32W108CB, STM32W108HB
Electrical characteristics
12.3.2
Operating conditions at power-up
Power-on resets (POR HV and POR LV)
The STM32W108 measures the voltage levels supplied to the three power domains. If a
supply voltage drops below a low threshold, then a reset is applied. The reset is released if
the supply voltage rises above a high threshold. There are three detection circuits for power
on reset as follows:
● POR HV monitors the always on domain supply voltage. Thresholds are given in
Table 27.
● POR LVcore monitors the core domain supply voltage. Thresholds are given in
Table 28.
● POR LVmem monitors the memory supply voltage. Thresholds are given in Table 29.
Table 27. POR HV thresholds
Parameter
Test conditions
Always-on domain release
Always-on domain assert
Supply rise time
From 0.5 V to 1.7 V
Min
Typ
Max Unit
1.0
1.2
1.4
V
0.5
0.6
0.7
V
250
µs
Table 28. POR LVcore thresholds
Parameter
Test conditions
1.25 V domain release
1.25 V domain assert
Min
Typ
Max Unit
0.9
1.0
1.1
V
0.8
0.9
1.0
V
Table 29. POR LVmem thresholds
Parameter
Test conditions
1.8 V domain release
1.8 V domain assert
Min
Typ
Max Unit
1.35
1.5
1.65
V
1.26
1.4
1.54
V
The POR LVcore and POR LVmem reset sources are merged to provide a single reset
source, POR LV, to the Reset Generation module, since the detection of either event needs
to reset the same system modules.
NRST pin
A single active low pin, NRST, is provided to reset the system. This pin has a Schmitt
triggered input.
To afford good noise immunity and resistance to switch bounce, the pin is filtered with the
Reset Filter module and generates the reset source RSTB to the Reset Generation module.
Table 30. Reset filter specification for RSTB
Parameter
Reset filter time constant
Min
Typ
Max Unit
2.1
12.0 16.0
µs
Doc ID 16252 Rev 2
159/179