P12C508 Microchip Technology, P12C508 Datasheet - Page 26

• Manufacturer Part Number: P12C508
• Description: 8-Pin / 8-Bit CMOS Microcontroller
• Manufacturer: Microchip Technology

PIC12C5XX
7.2
7.2.1
The PIC12C5XX can be operated in four different
oscillator modes. The user can program two
configuration bits (FOSC1:FOSC0) to select one of
these four modes:
• LP:
• XT:
• INTRC: Internal 4 MHz Oscillator
• EXTRC: External Resistor/Capacitor
7.2.2
In XT or LP modes, a crystal or ceramic resonator is
connected to the GP5/OSC1/CLKIN and GP4/OSC2
pins
PIC12C5XX oscillator design requires the use of a
parallel cut crystal. Use of a series cut crystal may
give a frequency out of the crystal manufacturers
specifications. When in XT or LP modes, the device
can have an external clock source drive the GP5/
OSC1/CLKIN pin (Figure 7-3).
FIGURE 7-2:
FIGURE 7-3:
DS40139A-page 26
Clock from
ext. system
Note 1: See Capacitor Selection tables for
to
2: A series resistor (RS) may be required for
3: RF varies with the crystal chosen
C2
C1
Oscillator Configurations
CRYSTAL OSCILLATOR / CERAMIC
RESONATORS
OSCILLATOR TYPES
(1)
(1)
recommended values of C1 and C2.
AT strip cut crystals.
(approx. value = 10 M ).
Low Power Crystal
Crystal/Resonator
establish
Open
RS
XTAL
(2)
CRYSTAL OPERATION (OR
CERAMIC RESONATOR) (XT
OR LP OSC
CONFIGURATION)
EXTERNAL CLOCK INPUT
OPERATION (XT OR LP OSC
CONFIGURATION)
OSC2
OSC1
oscillation
OSC2
OSC1
RF
(3)
PIC12C5XX
(Figure 7-2).
PIC12C5XX
To internal
Advanced Information
SLEEP
logic
The
TABLE 7-1:
TABLE 7-2:
These values are for design guidance only. Since
each resonator has its own characteristics, the user
should consult the resonator manufacturer for
appropriate values of external components.
Note 1: For V
These values are for design guidance only. Rs may
be required in HS mode as well as XT mode to avoid
overdriving crystals with low drive level specification.
Since each crystal has its own characteristics, the
user should consult the crystal manufacturer for
appropriate values of external components.
Type
Type
Osc
Osc
XT
XT
LP
recommended.
455 kHz
2.0 MHz
4.0 MHz
Resonator
Resonator
32 kHz
100 kHz
200 kHz
455 kHz
1 MHz
2 MHz
4 MHz
Freq
Freq
DD
CAPACITOR SELECTION
FOR CERAMIC RESONATORS
- PIC12C5XX
CAPACITOR SELECTION
FOR CRYSTAL OSCILLATOR
- PIC12C5XX
> 4.5V, C1 = C2
(1)
Cap. Range
Cap.Range
68-100 pF
1996 Microchip Technology Inc.
15-33 pF
10-22 pF
15-30 pF
15-30 pF
15-30 pF
15-30 pF
15 pF
15 pF
15 pF
C1
C1
30 pF is
Cap. Range
Cap. Range
200-300 pF
100-200 pF
68-100 pF
15-100 pF
15-33 pF
10-22 pF
15-30 pF
15 pF
15 pF
15 pF
C2
C2