PIC18F87K22 Datasheet, PDF (41/548 Pages) Microchip Technology – 64/80-Pin, High-Performance, 1-Mbit Enhanced Flash Microcontrollers with 12-Bit A/D and nanoWatt XLP Technology

PIC18F87K22 FAMILY
3.0 OSCILLATOR
CONFIGURATIONS
3.1 Oscillator Types
The PIC18F87K22 family of devices can be operated in
the following oscillator modes:
• EC
External clock, RA6 available
• ECIO External clock, clock out RA6 (FOSC/4 on
RA6)
• HS
High-Speed Crystal/Resonator
• XT
Crystal/Resonator
• LP
Low-Power Crystal
• RC
External Resistor/Capacitor, RA6
available
• RCIO External Resistor/Capacitor, clock out
RA6 (FOSC/4 on RA6)
• INTIO2 Internal Oscillator with I/O on RA6 and
RA7
• INTIO1 Internal Oscillator with FOSC/4 output on
RA6 and I/O on RA7
There is also an option for running the 4xPLL on any of
the clock sources in the input frequency range of 4 to
16 MHz.
The PLL is enabled by setting the PLLCFG bit
(CONFIG1H<4>) or the PLLEN bit (OSCTUNE<6>).
For the EC and HS mode, the PLLEN (software) or
PLLCFG (CONFIG) bit can be used to enable the PLL.
For the INTIOx modes (HF-INTOSC):
• Only the PLLEN can enable the PLL (PLLCFG is
ignored).
• When the oscillator is configured for the internal
oscillator (FOSC<3:0> = 100x), the PLL can be
enabled only when the HF-INTOSC frequency is
8 or 16 MHz.
When the RA6 and RA7 pins are not used for an oscil-
lator function or CLKOUT function, they are available
as general purpose I/Os.
To optimize power consumption when using EC/HS/
XT/LP/RC as the primary oscillator, the frequency input
range can be configured to yield an optimized power
bias:
• Low-Power Bias – External frequency less than
160 kHz
• Medium Power Bias – External frequency
between 160 kHz and 16 MHz
• High-Power Bias – External frequency greater
than 16 MHz
All of these modes are selected by the user by
programming the FOSC<3:0> Configuration bits
(CONFIG1H<3:0>). In addition, PIC18F87K22 family
devices can switch between different clock sources,
either under software control or, under certain condi-
tions, automatically. This allows for additional power
savings by managing device clock speed in real time
without resetting the application. The clock sources for
the PIC18F87K22 family of devices are shown in
Figure 3-1.
For the HS and EC mode, there are additional power
modes of operation – depending on the frequency of
operation.
HS1 is the Medium power mode with a frequency range
of 4 MHz to 16 MHz. HS2 is the High-Power mode,
where the oscillator frequency can go from 16 MHz to
25 MHz. HS1 and HS2 are achieved by setting the
CONFIG1H<3:0> correctly. (For details, see
Register 28-2 on page 404.)
EC mode has these modes of operation:
• EC1 – For low power with a frequency range up to
160 kHz
• EC2 – Medium power with a frequency range of
160 kHz to 16 MHz
• EC3 – High power with a frequency range of
16 MHz to 64 MHz
EC1, EC2 and EC3 are achieved by setting the
CONFIG1H<3:0> correctly. (For details, see
Register 28-2 on page 404.)
Table 3-1 shows the HS and EC modes’ frequency
range and FOSC<3:0> settings.
 2010 Microchip Technology Inc.
Preliminary
DS39960B-page 41