SM8521 datasheet(18/56 Pages) SHARP

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SM8521

- 18 -

SYSTEM CONTROL

Oscillator Circuit

The SM8521 is built-in the main-clock and sub-

clock oscillator circuits for generating clock signal.

The main-clock oscillator circuit is applied to 1.5 to

10 MHz. The sub-clock oscillator circuit is applied

to 32.768 kHz.

Clock System

The SM8521 uses the main-clock and sub-clock

oscillator circuits to generate the required clock.

The system clock, leads CPU operation, is one of

the five clocks which divides the main-clock (fCK)

into 1/2, 1/4, 1/8, 1/16 and 1/32. It also selects

from sub-clock (f32K). In addition, the clocks

supplied to the peripheral functions are fc1-fc10

divided by the prescaler PRS0 and derived from

the 1/2 clock of main-clock (fCK/2), and fx1-fx8 divided

by the prescaler PRS1 and derived from the sub-

clock.

fCK = 11.0592 MHz

System clock

frequency control

SM85CPU

Warming up counter

Sub-clock

generator circuit

Prescaler PRS1

CKIN

CKOUT

OSCIN

OSCOUT

RAM register

read/write

Function blocks

operation

Peripheral functions

Interrupt control

fCK/2

fc1-fc10

fc10

System clock

f32K

f32K =

32.768 kHz

Main-clock

generator circuit

1/2

Prescaler PRS0

fCK

Fig. 7

SM8521 Clock System

SM8521 Datasheet(PDF) 18 Page - Sharp Corporation

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