BLUENRG-MSCSP datasheet(17/42 Pages) STMICROELECTRONICS

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BlueNRG-MS

Block diagram and descriptions

Figure 11: Power management strategy using step-down DC-DC converter

5.3

Clock management

The BlueNRG-MS integrates two low-speed frequency oscillators (LSOSC) and two High

speed (16 MHz or 32 MHz) frequency oscillators (HSOSC).

The low frequency clock is used in Low Power mode and can be supplied either by a 32.7

kHz oscillator that uses an external crystal and guarantee up to ±50 ppm frequency

tolerance, or by a ring oscillator with maximum ±500 ppm frequency tolerance, which does

not require any external components.

The primary high frequency clock is a 16 MHz or 32 MHz crystal oscillator. There is also a

fast-starting 12 MHz ring oscillator that provides the clock while the crystal oscillator is

starting up. Frequency tolerance of high speed crystal oscillator is ±50 ppm.

The usage of the 16 MHz (or 32 MHz) crystal is strictly necessary.

5.4

Bluetooth low energy radio

The BlueNRG-MS integrates a RF transceiver compliant to the Bluetooth specification and

to the standard national regulations in the unlicensed 2.4 GHz ISM band.

The RF transceiver requires very few external discrete components. It provides 96 dB link

budgets with excellent link reliability, keeping the maximum peak current below 15 mA.

In Transmit mode, the power amplifier (PA) drives the signal generated by the frequency

synthesizer out to the antenna terminal through a very simple external network. The power

delivered as well as the harmonic content depends on the external impedance seen by the

PA.

DocID027103 Rev 6

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