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PIC18F23K20_10 Datasheet, PDF (31/456 Pages) Microchip Technology – 28/40/44-Pin Flash Microcontrollers with nanoWatt XLP Technology | |||
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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 2-3). 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 selects the highest gain setting of the
internal inverter-amplifier. HS mode current consumption
is the highest of the three modes. This mode is best
suited for resonators that require a high drive setting.
Figure 2-3 and Figure 2-4 show typical circuits for
quartz crystal and ceramic resonators, respectively.
FIGURE 2-3:
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 Mï to 10 Mïï©.
PIC18F2XK20/4XK20
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, reference
the following Microchip Applications Notes:
⢠AN826, âCrystal Oscillator Basics and
Crystal Selection for rfPIC® and PIC®
Devicesâ (DS00826)
⢠AN849, âBasic PIC® Oscillator Designâ
(DS00849)
⢠AN943, âPractical PIC® Oscillator
Analysis and Designâ (DS00943)
⢠AN949, âMaking Your Oscillator Workâ
(DS00949)
FIGURE 2-4:
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 Mï to 10 Mïï©.
3: An additional parallel feedback resistor (RP)
may be required for proper ceramic resonator
operation.
ï£ 2010 Microchip Technology Inc.
DS41303G-page 31
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