Power Supply Supervisor; Power-On Reset (Por) / Power-Down Reset (Pdr) / Brown-Out Reset; (Bor); Programmable Voltage Detector (Pvd) - ST STM32L4x6 Reference Manual

RM0351
5.2

Power supply supervisor

5.2.1

Power-on reset (POR) / power-down reset (PDR) / brown-out reset

(BOR)

The device has an integrated power-on reset (POR) / power-down reset (PDR), coupled
with a brown-out reset (BOR) circuitry. The BOR is active in all power modes except
Shutdown mode, and cannot be disabled.
Five BOR thresholds can be selected through option bytes.
During power-on, the BOR keeps the device under reset until the supply voltage V
reaches the specified V
device reset is generated. When V
released and the system can start.
For more details on the brown-out reset thresholds, refer to the electrical characteristics
section in the datasheet.
1. The reset temporization t
5.2.2

Programmable voltage detector (PVD)

You can use the PVD to monitor the V
selected by the PLS[2:0] bits in the
The PVD is enabled by setting the PVDE bit.
A PVDO flag is available, in the
higher or lower than the PVD threshold. This event is internally connected to the EXTI line16
and can generate an interrupt if enabled through the EXTI registers. The PVD output
interrupt can be generated when V
rises above the PVD threshold depending on EXTI line16 rising/falling edge configuration.
As an example, the service routine could perform emergency shutdown tasks.
threshold. When V
BORx
is above the V
DD

Figure 8. Brown-out reset waveform

is present only for the BOR lowest threshold (V
RSTTEMPO
power supply by comparing it to a threshold
DD
Power control register 2
Power status register 2
drops below the PVD threshold and/or when V
DD
DocID024597 Rev 3
Power control (PWR)
drops below the selected threshold, a
DD
upper limit, the device reset is
BORx
(PWR_CR2).
(PWR_SR2), to indicate if V
DD
).
BOR0
is
DD
DD
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