ST72561AR7-Auto datasheet(41/324 Pages) STMICROELECTRONICS

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ST72561-Auto

Supply, reset and clock management

Doc ID 12370 Rev 8

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Supply, reset and clock management

5.1

Introduction

The device includes a range of utility features for securing the application in critical

situations (for example, in case of a power brown-out), and reducing the number of external

components. An overview is shown in Figure 11.

For more details, refer to dedicated parametric section.

5.2

Main features

●

Optional PLL for multiplying the frequency by 2

●

Reset Sequence Manager (RSM)

●

Multi-Oscillator Clock Management (MO)

–

4 Crystal/Ceramic resonator oscillators

●

System Integrity Management (SI)

–

Main supply Low voltage detection (LVD)

–

Auxiliary Voltage detector (AVD) with interrupt capability for monitoring the main

supply

5.3

Phase locked loop

If the clock frequency input to the PLL is in the range 2 to 4 MHz, the PLL can be used to

multiply the frequency by two to obtain an fOSC2 of 4 to 8 MHz. The PLL is enabled by option

byte. If the PLL is disabled, then fOSC2 =fOSC/2.

Caution:

The PLL is not recommended for applications where timing accuracy is required.

Section 20.5.2: PLL characteristics

Figure 10.

PLL block diagram

PLL OPTION BIT

PLL x 2

fOSC2

/ 2

fOSC

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