PIC18F23K20-E/MLQTP MICROCHIP [Microchip Technology], PIC18F23K20-E/MLQTP Datasheet - Page 27

• Manufacturer Part Number: PIC18F23K20-E/MLQTP
• Description: 28/40/44-Pin Flash Microcontrollers with 10-Bit A/D and nanoWatt Technology
• Manufacturer: MICROCHIP [Microchip Technology]

2.0
2.1
The Oscillator module has a wide variety of clock
sources and selection features that allow it to be used
in a wide range of applications while maximizing perfor-
mance and minimizing power consumption. Figure 2-1
illustrates a block diagram of the Oscillator module.
Clock sources can be configured from external
oscillators, quartz crystal resonators, ceramic resonators
and Resistor-Capacitor (RC) circuits. In addition, the
system clock source can be configured from one of two
internal oscillators, with a choice of speeds selectable via
software. Additional clock features include:
• Selectable system clock source between external
• Two-Speed Start-up mode, which minimizes
• Fail-Safe Clock Monitor (FSCM) designed to
FIGURE 2-1:
© 2007 Microchip Technology Inc.
T1OSO
or internal via software.
latency between external oscillator start-up and
code execution.
detect a failure of the external clock source (LP,
XT, HS, EC or RC modes) and switch
automatically to the internal oscillator.
T1OSI
OSC2
OSC1
Note 1:
OSCILLATOR MODULE (WITH
FAIL-SAFE CLOCK MONITOR)
Overview
Primary Oscillator
Secondary Oscillator
Operates only when HFINTOSC is the primary oscillator.
FOSC<3:0> OSCCON<1:0>
Oscillator
PIC
Internal
16 MHz
Source
31 kHz
Source
Block
T1OSCEN
Enable
Oscillator
Sleep
31 kHz (LFINTOSC)
®
MCU CLOCK SOURCE BLOCK DIAGRAM
(HFINTOSC)
16 MHz
OSCTUNE<6>
Advance Information
PIC18F2XK20/4XK20
(1)
0
1
500 kHz
250 kHz
16 MHz
31 kHz
8 MHz
4 MHz
2 MHz
1 MHz
OSCCON<6:4>
OSCTUNE<7>
4 x PLL
111
110
101
100
011
010
001
000
The Oscillator module can be configured in one of ten
primary clock modes.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10. ECIO
Primary Clock modes are selected by the FOSC<3:0>
bits of the CONFIG1H Configuration Register. The
HFINTOSC and LFINTOSC are factory calibrated high-
frequency and low-frequency oscillators, respectively,
which are used as the internal clock sources.
PIC18F2XK20/4XK20
LP
XT
HS
HSPLL
RC
RCIO
INTOSC
INTOSCIO Internal Oscillator with I/O on RA6
EC
HSPLL, HFINTOSC/PLL
LP, XT, HS, RC, EC
Internal Oscillator
Low-Power Crystal
Crystal/Resonator
High-Speed Crystal/Resonator
High-Speed Crystal/Resonator
External Resistor/Capacitor with
External Resistor/Capacitor with I/O
Internal Oscillator with F
External Clock with F
External Clock with I/O on RA6
with PLL enabled
F
on RA6
output on RA6 and I/O on RA7
and RA7
OSC
FOSC<3:0>
T1OSC
/4 output on RA6
Clock Source Option
for other Modules
WDT, PWRT, FSCM
and Two-Speed Start-up
Control
Clock
OSCCON<1:0>
Main
IDLEN
Sleep
Sleep
DS41303B-page 25
OSC
OSC
/4 output
Peripherals
/4
CPU