August 27, 1998
GENERAL RELEASE SPECIFICATION
SECTION 8
SYSTEM CLOCK
This section describes the system clock options for the MC68HC05SB7.
8.1
CLOCK SOURCES
The internal operating clock of the MC68HC05SB7 is derived from two possible
clock sources:
•
External oscillator input via the OSC1 and OSC2 pins - this is enabled
by a mask option on the MC68HC05SB7.
(On the MC68HC705SB7, the OSCS bit in the Mask Option Register
enables/disables external osc input option.)
•
Internal VCO generated.
VCOEN
SCLK
VA0
VA1
VA2
VA3
VCO
f
MUX
÷ 2
OP
VA4
I/O PORT
OSC1
OSC2
OSC
OSCS
Figure 8-1. MC68HC05SB7 Input Clock Source
MC68HC05SB7
REV 2.1
SYSTEM CLOCK
MOTOROLA
8-1
FREESCALE [ Freescale ]
