Microchip Technology IC MCU FLASH 4K PIC16LF88-I/P DIP-18 MCP PIC16LF88-I/P 데이터 시트
제품 코드
PIC16LF88-I/P
2002-2013 Microchip Technology Inc.
DS30487D-page 35
PIC16F87/88
4.0
OSCILLATOR
CONFIGURATIONS
CONFIGURATIONS
4.1
Oscillator Types
The PIC16F87/88 can be operated in eight different
oscillator modes. The user can program three configu-
ration bits (FOSC2:FOSC0) to select one of these eight
modes (modes 5-8 are new PIC16 oscillator
configurations):
oscillator modes. The user can program three configu-
ration bits (FOSC2:FOSC0) to select one of these eight
modes (modes 5-8 are new PIC16 oscillator
configurations):
1.
LP
Low-Power Crystal
2.
XT
Crystal/Resonator
3.
HS
High-Speed Crystal/Resonator
4.
RC
External Resistor/Capacitor with
F
F
OSC
/4 output on RA6
5.
RCIO
External Resistor/Capacitor with
I/O on RA6
I/O on RA6
6.
INTIO1
Internal Oscillator with F
OSC
/4
output on RA6 and I/O on RA7
7.
INTIO2
Internal Oscillator with I/O on RA6
and RA7
and RA7
8.
ECIO
External Clock with I/O on RA6
4.2
Crystal Oscillator/Ceramic
Resonators
Resonators
In XT, LP or HS modes, a crystal or ceramic resonator
is connected to the OSC1/CLKI and OSC2/CLKO pins
to establish oscillation (see Figure 4-1 and Figure 4-2).
The PIC16F87/88 oscillator design requires the use of
a parallel cut crystal. Use of a series cut crystal may
give a frequency out of the crystal manufacturer’s
specifications.
is connected to the OSC1/CLKI and OSC2/CLKO pins
to establish oscillation (see Figure 4-1 and Figure 4-2).
The PIC16F87/88 oscillator design requires the use of
a parallel cut crystal. Use of a series cut crystal may
give a frequency out of the crystal manufacturer’s
specifications.
FIGURE 4-1:
CRYSTAL OPERATION
(HS, XT, OR LP
OSCILLATOR
CONFIGURATION)
(HS, XT, OR LP
OSCILLATOR
CONFIGURATION)
TABLE 4-1:
CAPACITOR SELECTION FOR
CRYSTAL OSCILLATOR (FOR
DESIGN GUIDANCE ONLY)
CRYSTAL OSCILLATOR (FOR
DESIGN GUIDANCE ONLY)
Note1: See Table 4-1 for typical values of C1 and C2.
2: A series resistor (R
S
) may be required for AT strip
cut crystals.
3: R
F
varies with the crystal chosen (typically
between 2 M
to 10 M.
C1
(1)
C2
(1)
XTAL
OSC2
R
S
(2)
OSC1
R
F
(3)
Sleep
To Internal
Logic
Logic
PIC16F87/88
Osc Type
Crystal
Freq
Typical Capacitor Values
Tested:
C1
C2
LP
32 kHz
33 pF
33 pF
XT
200 kHz
56 pF
56 pF
1 MHz
15 pF
15 pF
4 MHz
15 pF
15 pF
HS
4 MHz
15 pF
15 pF
8 MHz
15 pF
15 pF
20 MHz
15 pF
15 pF
Capacitor values are for design guidance only.
These capacitors were tested with the crystals listed
below for basic start-up and operation. These values
were not optimized.
below for basic start-up and operation. These values
were not optimized.
Different capacitor values may be required to produce
acceptable oscillator operation. The user should test
the performance of the oscillator over the expected
V
acceptable oscillator operation. The user should test
the performance of the oscillator over the expected
V
DD
and temperature range for the application.
See the notes following this table for additional
information.
information.
Note 1: Higher capacitance increases the stability
of oscillator but also increases the
start-up time.
start-up time.
2: Since each crystal has its own character-
istics, the user should consult the crystal
manufacturer for appropriate values of
external components.
manufacturer for appropriate values of
external components.
3: Rs may be required in HS mode, as well
as XT mode, to avoid overdriving crystals
with low drive level specification.
with low drive level specification.
4: Always verify oscillator performance over
the V
DD
and temperature range that is
expected for the application.