ST6285B View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
'ST6285B' PDF : 78 Pages View PDF
ST62T85B/E85B
3 CLOCKS, RESET, INTERRUPTS AND POWER SAVING MODES
3.1 CLOCK SYSTEM
3.1.1 Main Oscillator
Figure 8. Oscillator Configurations
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.
CRYSTAL/RESONATOR CLOCK
ST6xxx
Figure 8 illustrates various possible oscillator con-
figurations using an external crystal or ceramic res-
onator, an external clock input. CL1 an CL2 should
have a capacitance in the range 12 to 22 pF for an
oscillator frequency in the 4-8 MHz range.
OSCin
OSCout
The internal MCU clock Frequency (FINT) is divid-
ed by 13 to drive the CPU core and by 12 to drive
the A/D converter and the watchdog timer, while
clock used to drive on-chip peripherals depends
) on the peripheral as shown in the clock circuit
t(s block diagram.
c With an 8MHz oscillator frequency, the fastest ma-
u chine cycle is therefore 1.625µs.
rod A machine cycle is the smallest unit of time needed
to execute any operation (for instance, to increment
P the Program Counter). An instruction may require
te two, four, or five machine cycles for execution.
bsole Figure 9. Clock Circuit Block Diagram
- O fOSC
t(s) OSCin
c fINT
Produ MAIN
teOSCILLATOR
Obsole OSCout
CL1n
CL2
VA0016
EXTERNAL CLOCK
ST6xxx
OSCin
OSCout
NC
VA0015A
POR
: 13
Core
Timer 1
fINT
: 12
Watchdog
ADC
UART
ARTIMER
LCD
CONTROLLER
DRIVER
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