RM0440 Rev 4 235/2126
RM0440 Power control (PWR)
271
1. Set the R1MODE bit is in the PWR_CR5 register.
2. Adjust the number of wait states according new frequency target in Range1 default
mode.
3. Configure and switch to new system frequency.
6.2 Power supply supervisor
6.2.1 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.
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