STM32F401CD datasheet(20/135 Pages) STMICROELECTRONICS

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Functional overview

STM32F401xD STM32F401xE

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DocID025644 Rev 3

3.14

Power supply supervisor

3.14.1

Internal reset ON

This feature is available for VDD operating voltage range 1.8 V to 3.6 V.

The internal power supply supervisor is enabled by holding PDR_ON high.

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 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

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.

3.14.2

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 by setting the PDR_ON pin to

low.

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 5: Power supply supervisor

interconnection with internal reset OFF.

Figure 5. Power supply supervisor interconnection with internal reset OFF(1)

1. The PRD_ON pin is only available in the WLCSP49 and UFBGA100 packages.

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