ST6232BB1(2003) 데이터 시트보기 (PDF) - STMicroelectronics

부품명

상세내역

제조사

ST6232BB1
(Rev.:2003)

8-BIT OTP/EPROM MCUs WITH A/D CONVERTER, 16-BIT AUTO-RELOAD TIMER, EEPROM, SPI AND UART

STMicroelectronics 

ST62T32B ST62E32B

3 CLOCKS, RESET, INTERRUPTS AND POWER SAVING MODES

3.1 CLOCK SYSTEM

The MCU features a Main Oscillator which can be

driven by an external clock, or used in conjunction

with an AT-cut parallel resonant crystal or a suita-

ble ceramic resonator. In addition, a Low Frequen-

cy Auxiliary Oscillator (LFAO) can be switched in

for security reasons, to reduce power consump-

tion, or to offer the benefits of a back-up clock sys-

tem.

The Oscillator Safeguard (OSG) option filters

spikes from the oscillator lines, provides access to

the LFAO to provide a backup oscillator in the

event of main oscillator failure and also automati-

cally limits the internal clock frequency (fINT) as a

function of VDD, in order to guarantee correct oper-

ation. These functions are illustrated in Figure 10,

Figure 11, Figure 12 and Figure 13.

Figure 9 illustrates various possible oscillator con-

figurations using an external crystal or ceramic res-

onator, an external clock input or the lowest cost so-

lution using only the LFAO. CL1 an CL2 should have

a capacitance in therange 12 to 22 pFforan oscillator

frequency in the 4-8 MHz range.

The internal MCU clock frequency (fINT) is divided

by 12 to drive the Timer and the Watchdog timer,

and by 13 to drive the CPU core, while the A/D

converter is driven by fINT divided either by 6 or by

12 as may be seen in Figure 12.

With an 8 MHz oscillator frequency, the fastest ma-

chine cycle is therefore 1.625µs.

A machine cycle is the smallest unit of time needed

to execute any operation (for instance, to increment

the Program Counter). An instruction may require

two, four, or five machine cycles for execution.

3.1.1 Main Oscillator

The main oscillator can be turned off (when the

OSG ENABLED option is selected) by setting the

OSCOFF bit of the OSCR Control Register. The

Low Frequency Auxiliary Oscillator is automatical-

ly started.

Figure 9. Oscillator Configurations

CRYSTAL/RESONATOR CLOCK

ST6xxx

OSCin

OSCout

CL1n

CL2

VA0016

EXTERNAL CLOCK

ST6xxx

OSCin

OSCout

NC

VA0015A

INTEGRATED CLOCK

OSG ENABLED option

ST6xxx

OSCin

OSCout

NC

18/84

Share Link: