ATSAMB11XR datasheet(17/87 Pages) MICROCHIP

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Clocking

6.1

Overview

Figure 6-1. Clock Architecture

Figure 6-1 provides an overview of the clock tree and clock management blocks.

The BLE Clock is used to drive the BLE subsystem. The ARM clock is used to drive the Cortex-M0 MCU

and its interfaces (UART, SPI, and I2C); the recommended MCU clock speed is 26 MHz. The Low Power

Clock is used to drive all the low-power applications like the BLE sleep timer, always-on power

sequencer, always-on timer, and others.

The 26 MHz integrated RC Oscillator is used for most general purpose operations on the MCU and its

peripherals. In cases when the BLE subsystem is not used, the RC oscillator can be used for lower power

consumption. The frequency variation of this RC oscillator is up to ±50% over process, voltage, and

temperature.

The frequency variation of 2 MHz integrated RC Oscillator is up to ±50% over process, voltage, and

temperature.

The 32.768 kHz RTC Crystal Oscillator (RTC XO) is used for BLE operations as it will reduce power

consumption by providing the best timing for wake-up precision, allowing circuits to be in low-power sleep

mode for as long as possible until they need to wake-up and connect during the BLE connection event.

6.2

26 MHz Crystal Oscillator (XO)

A 26 MHz crystal oscillator is integrated into the ATSAMB11-XR2100A and ATSAMB11-ZR210CA to

provide the precision clock for the BLE operations.

ATSAMB11XR/ZR

Datasheet Preliminary

DS70005342A-page 17

ATSAMB11XR Datasheet(PDF) 17 Page - Microchip Technology