BLUENRG-2 datasheet(17/190 Pages) STMICROELECTRONICS

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BlueNRG-2

Functional details

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The access to the static RAM can be bytes, half words (16 bits) or words (32 bits).

A 12 KB RAM block is always in retention mode, whereas the second 12 KB RAM block is

switchable and can be put in retention mode according to the user needs.

3.4

Power management

The BlueNRG-2 integrates both a low dropout voltage regulator (LDO) and a step-down

DC-DC converter to supply the internal BlueNRG-2 circuitry.

The BlueNRG-2 most efficient power management configuration is with DC-DC converter

active where best power consumption is obtained without compromising performances.

Nevertheless, a configuration based on LDO can also be used, if needed.

A simplified version of the state machine is shown below.

Figure 5: BlueNRG-2 power management state machine

3.4.1

States description

3.4.1.1

Preactive state

The preactive state is the default state after a POR event.

In this state:



All the digital power supplies are stable.



The high frequency clock runs on internal fast clock RC oscillator (16 MHz).



The low frequency clock runs on internal RC oscillator (32.768 kHz).

3.4.1.2

Active state

In this state:



The high frequency runs on the accurate clock (16 MHz ±50 ppm) provided by the

external XO. The internal fast clock RO oscillator is switched off.

BLUENRG-2 Datasheet(PDF) 17 Page - STMicroelectronics