ST STM32L0x3 User Manual

Power control (PWR) RM0367
150/1043 RM0367 Rev 7
6.2.1 Power-on reset (POR)/power-down reset (PDR)
The device has an integrated POR/PDR circuitry that allows operation down to 1.5 V.
During power-on, the device remains in Reset mode when V
DD
/V
DDA
is below a specified
threshold, V
POR
, without the need for an external reset circuit. The POR feature is always
enabled and the POR threshold is 1.5 V.
During power-down, the PDR keeps the device under reset when the supply voltage (V
DD
)
drops below the V
PDR
threshold. The PDR feature is always enabled and the PDR threshold
is 1.5 V.
The POR and PDR are used only when the BOR is disabled (see Section 6.2.2: Brown out
reset (BOR))). To insure the minimum operating voltage (1.65 V), the BOR should be
configured to BOR Level 1. When the BOR is disabled, a “gray zone” exist between the
minimum operating voltage (1.65 V) and the V
POR
/V
PDR
threshold. This means that V
DD
can be lower than 1.65 V without device reset until the V
PDR
threshold is reached.
For more details concerning the power-on/power-down reset threshold, refer to the
electrical characteristics of the datasheet.
Figure 13. Power-on reset/power-down reset waveform
6.2.2 Brown out reset (BOR)
During power-on, the Brown out reset (BOR) keeps the device under reset until the supply
voltage reaches the specified V
BOR
threshold.
For devices operating from 1.65 to 3.6 V, the BOR option is not available and the power
supply is monitored by the POR/PDR. As the POR/PDR thresholds are at 1.5 V, a “gray
zone” exists between the V
POR
/V
PDR
thresholds and the minimum product operating
voltage 1.65 V.
For devices operating from 1.8 to 3.6 V, the BOR is always active at power-on and it's
threshold is 1.8 V.
Then when the system reset is released, the BOR level can be reconfigured or disabled by
option byte loading.
If the BOR level is kept at the lowest level, 1.8 V at power-on and 1.65 V at power-down, the
system reset is fully managed by the BOR and the product operating voltages are within
safe ranges.
MS32793V1
VDD/VDDA
Reset
POR
PDR
Temporization
tRSTTEMPO

ST STM32L0x3 Specifications

General

Brand	ST
Model	STM32L0x3
Category	Microcontrollers
Language	English