PIC16F684
3.3.3
LP, XT, HS MODES
FIGURE 3-4:
CERAMIC RESONATOR
OPERATION
(XT OR HS MODE)
The LP, XT and HS modes support the use of quartz
crystal resonators or ceramic resonators connected to
the OSC1 and OSC2 pins (Figure 3-1). The mode
selects a low, medium or high gain setting of the
internal inverter-amplifier to support various resonator
types and speed.
PIC16F684
OSC1
C1
To Internal
Logic
LP Oscillator mode selects the lowest gain setting of
the internal inverter-amplifier. LP mode current con-
sumption 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.
(3)
(2)
RF
Sleep
RP
OSC2
(1)
RS
C2
Ceramic
Resonator
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, for example,
low-frequency/AT-cut quartz crystal resonators.
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 MΩ to
10 MΩ).
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, for example, high-frequency/AT-cut
quartz crystal resonators or ceramic resonators.
3: An additional parallel feedback resistor (RP)
may be required for proper ceramic resonator
operation (typical value 1 MΩ).
Figure 3-3 and Figure 3-4 show typical circuits for
quartz crystal and ceramic resonators, respectively.
FIGURE 3-3:
QUARTZ CRYSTAL
OPERATION (LP, XT OR
HS MODE)
PIC16F684
OSC1
C1
To Internal
Logic
Quartz
Crystal
(2)
RF
Sleep
OSC2
(1)
RS
C2
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 MΩ to
10 MΩ).
Note 1: Quartz crystal characteristics vary
according to type, package and manufac-
turer. The user should consult the manu-
facturer data sheets for specifications and
recommended application.
2: Always verify oscillator performance over
the VDD and temperature range that is
expected for the application.
2004 Microchip Technology Inc.
Preliminary
DS41202C-page 21
MICROCHIP [ MICROCHIP ]
