Power control (PWR) RM0351
158/1830 DocID024597 Rev 5
If in Range 1, then the following step can be applied:
5. Increase the system frequency if needed.
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
DD
reaches the specified V
BORx
threshold. When V
DD
drops below the selected threshold, a
device reset is generated. When V
DD
is above the V
BORx
upper limit, the device reset is
released and the system can start.
For more details on the brown-out reset thresholds, refer to the electrical characteristics
section in the datasheet.
Figure 11. Brown-out reset waveform
1. The reset temporization t
RSTTEMPO
is present only for the BOR lowest threshold (V
BOR0
).
5.2.2 Programmable voltage detector (PVD)
You can use the PVD to monitor the V
DD
power supply by comparing it to a threshold
selected by the PLS[2:0] bits in the Power control register 2 (PWR_CR2).
The PVD is enabled by setting the PVDE bit.
A PVDO flag is available, in the Power status register 2 (PWR_SR2), to indicate if V
DD
is
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
DD
drops below the PVD threshold and/or when V
DD
rises above the PVD threshold depending on EXTI line16 rising/falling edge configuration.
As an example, the service routine could perform emergency shutdown tasks.
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