DocID022152 Rev 4
The device also features an embedded programmable voltage detector (PVD) that monitors
the VDD/VDDA power supply and compares it to the VPVD threshold. An interrupt can be
generated when VDD/VDDA drops below the VPVD threshold and/or when VDD/VDDA is
higher than the VPVD threshold. The interrupt service routine can then generate a warning
message and/or put the MCU into a safe state. The PVD is enabled by software.
Internal reset OFF
This feature is available only on packages featuring the PDR_ON pin. The internal power-on
reset (POR) / power-down reset (PDR) circuitry is disabled with the PDR_ON pin.
An external power supply supervisor should monitor VDD and should maintain the device in
reset mode as long as VDD is below a specified threshold. PDR_ON should be connected to
this external power supply supervisor. Refer to Figure 7: Power supply supervisor
interconnection with internal reset OFF.
Figure 7. Power supply supervisor interconnection with internal reset OFF
1. PDR = 1.7 V for reduce temperature range; PDR = 1.8 V for all temperature range.
The VDD specified threshold, below which the device must be maintained under reset, is
1.8 V (see Figure 7). This supply voltage can drop to 1.7 V when the device operates in the
0 to 70 °C temperature range.
A comprehensive set of power-saving mode allows to design low-power applications.
When the internal reset is OFF, the following integrated features are no more supported:
The integrated power-on reset (POR) / power-down reset (PDR) circuitry is disabled
The brownout reset (BOR) circuitry is disabled
The embedded programmable voltage detector (PVD) is disabled
VBAT functionality is no more available and VBAT pin should be connected to VDD
All packages, except for the LQFP64 and LQFP100, allow to disable the internal reset
through the PDR_ON signal.
External VDD power supply supervisor
Ext. reset controller active when
VDD < 1.7 V or 1.8 V