STM32W108HB datasheet(34/179 Pages) STMICROELECTRONICS

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System modules

STM32W108CB, STM32W108HB

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Doc ID 16252 Rev 2

5.1

Power domains

The STM32W108 contains three power domains:

●

An "always on domain" containing all logic and analog cells required to manage the

STM32W108's power modes, including the GPIO controller and sleep timer. This

domain must remain powered.

●

A "core domain" containing the CPU, Nested Vectored Interrupt Controller (NVIC), and

peripherals. To save power, this domain can be powered down using a mode called

deep sleep.

●

A "memory domain" containing the RAM and flash memories. This domain is managed

by the power management controller. When in deep sleep, the RAM portion of this

domain is powered from the always-on domain supply to retain the RAM contents while

the regulators are disabled. During deep sleep the flash portion is completely powered

down.

5.1.1

Internally regulated power

The preferred and recommended power configuration is to use the internal regulated power

supplies to provide power to the core and memory domains. The internal regulators

(VREG_1V25 and VREG_1V8) generate nominal 1.25 V and 1.8 V supplies. The 1.25 V

supply is internally routed to the core domain and to an external pin. The 1.8 V supply is

routed to an external pin where it can be externally routed back into the chip to supply the

memory domain. The internal regulators are described in Section 1.2.10: Voltage regulator

on page 13.

When using the internal regulators, the always-on domain must be powered between 2.1 V

and 3.6 V at all four VDD_PADS pins.

When using the internal regulators, the VREG_1V8 regulator output pin (VREG_OUT) must

be connected to the VDD_MEM, VDD_PADSA, VDD_VCO, VDD_RF, VDD_IF, VDD_PRE,

and VDD_SYNTH pins.

When using the internal regulators, the VREG_1V25 regulator output and supply requires a

connection between both VDD_CORE pins.

5.1.2

Externally regulated power

Optionally, the on-chip regulators may be left unused, and the core and memory domains

may instead be powered from external supplies. For simplicity, the voltage for the core

domain can be raised to nominal 1.8 V, requiring only one external regulator. Note that if the

core domain is powered at a higher voltage (1.8 V instead of 1.25 V) then power

consumption increases. A regulator enable signal, REG_EN, is provided for control of

external regulators. This is an open-drain signal that requires an external pull-up resistor. If

REG_EN is not required to control external regulators it can be disabled (see Section 6.1.3:

Forced functions on page 48).

Using an external regulator requires the always-on domain to be powered between 1.8 V

and 3.6 V at all four VDD_PADS pins.

When using an external regulator, the VREG_1V8 regulator output pin (VREG_OUT) must

be left unconnected.

When using an external regulator, this external nominal 1.8 V supply has to be connected to

both VDD_CORE pins and to the VDD_MEM, VDD_PADSA, VDD_VCO, VDD_RF, VDD_IF,

VDD_PRE and VDD_SYNTH pins.

STM32W108HB Datasheet(PDF) 34 Page - STMicroelectronics

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