Datasheet

 2007-2012 Microchip Technology Inc. DS39778E-page 37
PIC18F87J11 FAMILY
3.0 OSCILLATOR
CONFIGURATIONS
3.1 Oscillator Types
The PIC18F87J11 family of devices can be operated in
eight different oscillator modes:
1. HS High-Speed Crystal/Resonator
2. HSPLL High-Speed Crystal/Resonator
with Software PLL Control
3. EC External Clock with F
OSC/4 Output
4. ECPLL External Clock with Software PLL
Control
5. INTIO1 Internal Oscillator Block with F
OSC/4
Output on RA6 and I/O on RA7
6. INTIO2 Internal Oscillator Block with I/O on
RA6 and RA7
7. INTPLL1 Internal Oscillator Block with
Software
PLL Control, F
OSC/4 Output on RA6
and I/O on RA7
8. INTPLL2 Internal Oscillator Block with Software
PLL Control and I/O on RA6 and RA7
All of these modes are selected by the user by
programming the FOSC<2:0> Configuration bits.
In addition, PIC18F87J11 family devices can switch
between different clock sources, either under software
control or automatically under certain conditions. This
allows for additional power savings by managing
device clock speed in real time without resetting the
application.
The clock sources for the PIC18F87J11 family of
devices are shown in Figure 3-1.
FIGURE 3-1: PIC18F87J11 FAMILY CLOCK DIAGRAM
PIC18F87J11 Family
4 x PLL
FOSC<2:0>
T1OSCEN
Enable
Oscillator
T1OSO
T1OSI
Clock Source Option
for Other Modules
OSC1
OSC2
Sleep
HSPLL, ECPLL, INTPLL
HS, EC
T1OSC
CPU
Peripherals
IDLEN
Postscaler
MUX
MUX
8 MHz
4 MHz
2 MHz
1 MHz
500 kHz
125 kHz
250 kHz
OSCCON<6:4>
111
110
101
100
011
010
001
000
31 kHz
INTRC
Source
Internal
Oscillator
Block
WDT, PWRT, FSCM
8 MHz
Internal Oscillator
(INTOSC)
OSCCON<6:4>
Clock
Control
OSCCON<1:0>
Source
8 MHz
31 kHz (INTRC)
0
1
OSCTUNE<7>
and Two-Speed Start-up
Primary Oscillator
OSCTUNE<6>
Secondary Oscillator