PIC18F6X2X Datasheet, PDF (26/386 Pages) Microchip Technology – 64/80-Pin High Performance, 64-Kbyte Enhanced FLASH Microcontrollers with A/D

PIC18F6X2X/8X2X
2.6 Oscillator Switching Feature
The PIC18F6X2X/8X2X devices include a feature that
allows the system clock source to be switched from the
main oscillator to an alternate low frequency clock
source. For the PIC18F6X2X/8X2X devices, this
alternate clock source is the Timer1 oscillator. If a low
frequency crystal (32 kHz, for example) has been
attached to the Timer1 oscillator pins and the Timer1
oscillator has been enabled, the device can switch to a
Low Power Execution mode. Figure 2-7 shows a block
diagram of the system clock sources. The clock
switching feature is enabled by programming the
Oscillator Switching Enable (OSCSEN) bit in the
CONFIG1H Configuration register to a ‘0’. Clock
switching is disabled in an erased device. See
Section 12.0 for further details of the Timer1 oscillator.
See Section 24.0 for Configuration register details.
FIGURE 2-7:
DEVICE CLOCK SOURCES
PIC18F6X2X/8X2X
OSC2
OSC1
T1OSO
T1OSI
Main Oscillator
SLEEP
Timer1 Oscillator
4 x PLL
TOSC
TOSC/4
TT1P
T1OSCEN
Enable
Oscillator
Clock Source Option
for Other Modules
Clock
Source
TSCLK
DS39612A-page 24
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