PIC16HV785-I/SO View Datasheet(PDF) - Microchip Technology
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PIC16HV785-I/SO Datasheet PDF : 206 Pages
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3.3.3 LP, XT, HS MODES
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 inter-
nal 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 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.
XT Oscillator mode selects the intermediate gain set-
ting 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, AT-cut quartz
crystal resonators.
HS Oscillator mode selects the highest gain setting of
the internal inverter-amplifier. HS mode current con-
sumption is the highest of the three modes. This mode
is best suited for resonators that require a high drive
setting, for example, AT-cut quartz crystal resonators or
ceramic resonators.
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)
OSC1
C1
Quartz
Crystal
OSC2
RS(1)
C2
PIC16F785/HV785
RF(2)
Sleep
To Internal
Logic
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.
PIC16F785/HV785
FIGURE 3-4:
CERAMIC RESONATOR
OPERATION
(XT OR HS MODE)
OSC1
C1
RP(3)
OSC2
RS(1)
C2 Ceramic
Resonator
PIC16F785/HV785
RF(2)
Sleep
To Internal
Logic
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).
3: An additional parallel feedback resistor (RP)
may be required for proper ceramic resonator
operation (typical value 1 MΩ).
TABLE 3-2: CERAMIC RESONATORS
Mode
Freq.
OSC1 (C1) OSC2 (C2)
XT
HS
Note:
455 kHz
2.0 MHz
68-100 pF 68-100 pF
15-68 pF 15-68 pF
4.0 MHz
8.0 MHz
16.0 MHz
10-68 pF
15-68 pF
10-22 pF
10-68 pF
15-68 pF
10-22 pF
These values are for design guidance
only. See notes following this table.
© 2008 Microchip Technology Inc.
DS41249E-page 25
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