PIC18F23K22 Datasheet, PDF (35/492 Pages) Microchip Technology – 28/40/44-Pin, Low-Power, High-Performance Microcontrollers with nanoWatt XLP Technology

2.4.3 LP, XT, HS MODES
The LP, XT and HS modes support the use of quartz
crystal resonators or ceramic resonators connected to
OSC1 and OSC2 (Figure 2-6). The mode selects a low,
medium or high gain setting of the internal inverter-
amplifier to support various resonator types and speed.
LP Oscillator mode selects the lowest gain setting of the
internal inverter-amplifier. LP mode current consumption
is the least of the three modes. This mode is best suited
to drive resonators with a low drive level specification, for
example, tuning fork type crystals.
XT Oscillator mode selects the intermediate gain
setting of the internal inverter-amplifier. XT mode
current consumption is the medium of the three modes.
This mode is best suited to drive resonators with a
medium drive level specification.
HS Oscillator mode offers a Medium Power (MP) and a
High Power (HP) option selectable by the FOSC<3:0>
bits. The MP selections are best suited for oscillator
frequencies between 4 and 16 MHz. The HP selection
has the highest gain setting of the internal inverter-
amplifier and is best suited for frequencies above
16 MHz. HS mode is best suited for resonators that
require a high drive setting.
FIGURE 2-6:
QUARTZ CRYSTAL
OPERATION (LP, XT OR
HS MODE)
PIC^® MCU
C1
Quartz
Crystal
OSC1/CLKIN
RF⁽²⁾
To Internal
Logic
Sleep
C2
RS⁽¹⁾
OSC2/CLKOUT
Note 1: A series resistor (RS) may be required for
quartz crystals with low drive level.
2: The value of RF varies with the Oscillator mode
selected (typically between 2 M to 10 M.
PIC18(L)F2X/4XK22
Note 1: Quartz crystal characteristics vary according
to type, package and manufacturer. The
user should consult the manufacturer data
sheets for specifications and recommended
application.
2: Always verify oscillator performance over
the VDD and temperature range that is
expected for the application.
3: For oscillator design assistance, refer to the
following Microchip Application Notes:
• AN826, “Crystal Oscillator Basics and
Crystal Selection for rfPIC^® and PIC^®
Devices” (DS00826)
• AN849, “Basic PIC^® Oscillator Design”
(DS00849)
• AN943, “Practical PIC^® Oscillator
Analysis and Design” (DS00943)
• AN949, “Making Your Oscillator Work”
(DS00949)
FIGURE 2-7:
CERAMIC RESONATOR
OPERATION
(XT OR HS MODE)
PIC^® MCU
OSC1/CLKIN
C1
To Internal
Logic
RP⁽³⁾
RF⁽²⁾
Sleep
C2 _{Ceramic RS}⁽¹⁾
Resonator
OSC2/CLKOUT
Note 1: A series resistor (RS) may be required for
ceramic resonators with low drive level.
2: The value of RF varies with the Oscillator mode
selected (typically between 2 M to 10 M.
3: An additional parallel feedback resistor (RP)
may be required for proper ceramic resonator
operation.
 2010 Microchip Technology Inc.
Preliminary
DS41412B-page 35