STM32F479AI datasheet(28/208 Pages) STMICROELECTRONICS

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Functional overview

STM32F479xx

28/208

DocID028010 Rev 2

2.19

Power supply supervisor

2.19.1

Internal reset ON

On packages embedding the PDR_ON pin, the power supply supervisor is enabled by

holding PDR_ON high. On the other package, the power supply supervisor is always

enabled.

The device has an integrated power-on reset (POR)/ power-down reset (PDR) circuitry

coupled with a Brownout reset (BOR) circuitry. At power-on, POR/PDR is always active and

ensures proper operation starting from 1.8 V. After the 1.8 V POR threshold level is

reached, the option byte loading process starts, either to confirm or modify default BOR

thresholds, or to disable BOR permanently. Three BOR thresholds are available through

option bytes. The device remains in reset mode when VDD is below a specified threshold,

VPOR/PDR or VBOR, without the need for an external reset circuit.

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.

2.19.2

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 through the PDR_ON pin.

An external power supply supervisor should monitor VDD and NRST and should maintain

the device in reset mode as long as VDD is below a specified threshold. PDR_ON must be

connected to VSS, as shown in Figure 8.

Figure 8. Power supply supervisor interconnection with internal reset OFF

The VDD specified threshold, below which the device must be maintained under reset, is

1.7 V (see Figure 9).

A comprehensive set of power-saving mode allows to design low-power applications.

STM32F479AI Datenblatt(PDF) 28 Page - STMicroelectronics