Nrst Circuitry Example (For Stm32F411Xx And Stm32F446Xx Only); Figure 7. Nrst Circuitry Example - ST STM32F4 Series Getting Started

Power supplies
2.3.5

NRST circuitry example (for STM32F411xx and STM32F446xx only)

This example applies to STM32F411xx and STM32F446xx where PDR_ON can be
connected to VSS to permanently disable internal reset circuitry.
Restrictions:
•
PDR_ON = 0 is mostly intended for V
5% supply).
Supply ranges which never go below 1.8V minimum should be better managed by
internal circuitry (no additional component needed, thanks to fully embedded reset
controller).
•
When the internal reset is OFF, the following integrated features are no longer
supported:
–
–
–
–
Even with PDR_ON=0, during power up, the NRST is driven low by internal Reset controller
during T
RSTTEMPO
STM32F4xxxx datasheets for actual timing value.
14/44
The integrated power-on reset (POR) / power-down reset (PDR) circuitry is
disabled.
The brownout reset (BOR) circuitry must be disabled.
The embedded programmable voltage detector (PVD) is disabled.
VBAT functionality is no more available and VBAT pin should be connected to
V .
DD

Figure 7. NRST circuitry example

(only for STM32F411xx and STM32F446xx)
in order to allow stabilization of internal analog circuitry. Refer to
DocID026304 Rev 3
supply between 1.7 V and 1.9V (i.e. 1.8V +/-
DD
AN4488