STM32L4P5CE datasheet(23/311 Pages) STMICROELECTRONICS

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DS12903 Rev 2

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STM32L4P5xx

Functional overview

3.7

Power supply management

3.7.1

Power supply schemes

The STM32L4P5xx devices require a 1.71 V to 3.6 V VDD operating voltage supply. Several

independent supplies can be provided for specific peripherals:

•

VDD = 1.71 V to 3.6 V

VDD is the external power supply for the I/Os, the internal regulator and the system

analog such as reset, power management and internal clocks. It is provided externally

through the VDD pins.

•

VDD12 = 1.00 to 1.32 V

VDD12 is the external power supply bypassing the internal regulator when connected to

an external SMPS. It is provided externally through VDD12 pins and only available on

packages with the external SMPS supply option. VDD12 does not require any external

decoupling capacitance and cannot support any external load.

•

VDDA = 1.62 V (ADCs/COMPs) / 1.8 V (DACs/OPAMPs) to 2.4 V (VREFBUF) to 3.6 V

VDDA is the external analog power supply for A/D converters, D/A converters, voltage

reference buffer, operational amplifiers and comparators. The VDDA voltage level is

independent from the VDD voltage and should preferably be connected to VDD when

these peripherals are not used.

•

VDDUSB = 3.0 V to 3.6 V

VDDUSB is the external independent power supply for USB transceivers. The

VDDUSB voltage level is independent from the VDD voltage and should preferably be

connected to VDD when the USB is not used.

•

VDDIO2 = 1.08 V to 3.6 V

•

VDDIO2 is the external power supply for 14 I/Os (port G[15:2]). The VDDIO2 voltage

level is independent from the VDD voltage and should preferably be connected to VDD

when PG[15:2] are not used.

•

VBAT = 1.55 V to 3.6 V

VBAT is the power supply for RTC, external clock 32 kHz oscillator and backup registers

(through power switch) when VDD is not present.

•

VREF-, VREF+

VREF+ is the input reference voltage for ADCs and DACs. It is also the output of the

internal voltage reference buffer when enabled.

When VDDA < 2 V VREF+ must be equal to VDDA.

When VDDA ≥ 2 V VREF+ must be between 2 V and VDDA.

VREF+ can be grounded when ADC and DAC are not active.

The internal voltage reference buffer supports two output voltages, which are

configured with VRS bit in the VREFBUF_CSR register:

–VREF+ around 2.048 V. This requires VDDA equal to or higher than 2.4 V.

–VREF+ around 2.5 V. This requires VDDA equal to or higher than 2.8 V.

VREF- and VREF+ pins are not available on all packages. When not available, they are

bonded to VSSA and VDDA, respectively.

When the VREF+ is double-bonded with VDDA in a package, the internal voltage

reference buffer is not available and must be kept disable (refer to datasheet for

packages pinout description).

VREF- must always be equal to VSSA.

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