PIC18LF8720 Microchip Technology, PIC18LF8720 Datasheet - Page 26

• Manufacturer Part Number: PIC18LF8720
• Description: (PIC18LF6620/6520/8520/6620/8620/6720/8720) 64/80-Pin High-Performance / 64-Kbyte Enhanced Flash Microcontrollers
• Manufacturer: Microchip Technology

PIC18F6520/8520/6620/8620/6720/8720
2.6
The PIC18FXX20 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 PIC18FXX20 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
FIGURE 2-7:
DS39609B-page 24
Oscillator Switching Feature
OSC2
OSC1
T1OSO
T1OSI
DEVICE CLOCK SOURCES
Timer1 Oscillator
Main Oscillator
PIC18FXX20
T1OSCEN
Enable
Oscillator
Sleep
Clock Source Option
for other Modules
4 x PLL
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 Configuration Register 1H to a
‘0’. Clock switching is disabled in an erased device.
See Section 12.0 “Timer1 Module” for further details
of the Timer1 oscillator. See Section 23.0 “Special
Features of the CPU” for Configuration register
details.
T
T
T
OSC
1
P
T
OSC
/4
Source
Clock
 2004 Microchip Technology Inc.
T
SCLK