PIC16C620 Microchip Technology, PIC16C620 Datasheet - Page 47

• Manufacturer Part Number: PIC16C620
• Description: EPROM-Based 8-Bit CMOS Microcontroller
• Manufacturer: Microchip Technology

9.2
9.2.1
The PIC16C62X can be operated in four different
oscillator options. The user can program two
configuration bits (FOSC1 and FOSC0) to select one of
these four modes:
• LP
crystal manufacturers specifications. When in XT, LP or
HS modes, the device can have an external clock
source to drive the OSC1 pin (Figure 9-3).
FIGURE 9-2:
FIGURE 9-3:
• XT
• HS
• RC
9.2.2
In XT, LP or HS modes a crystal or ceramic resonator
is connected to the OSC1 and OSC2 pins to establish
oscillation (Figure 9-2). The PIC16C62X oscillator
design requires the use of a parallel cut crystal. Use of
a series cut crystal may give a frequency out of the
See Table 9-1 and Table 9-2 for recommended
values of C1 and C2.
1998 Microchip Technology Inc.
Clock from
ext. system
Note:
Open
C1
C2
Oscillator Configurations
CRYSTAL OSCILLATOR / CERAMIC
RESONATORS
OSCILLATOR TYPES
Low Power Crystal
Crystal/Resonator
High Speed Crystal/Resonator
Resistor/Capacitor
A series resistor may be required for
AT strip cut crystals.
see Note
XTAL
RS
CRYSTAL OPERATION
(OR CERAMIC RESONATOR)
(HS, XT OR LP OSC
CONFIGURATION)
EXTERNAL CLOCK INPUT
OPERATION (HS, XT OR LP
OSC CONFIGURATION)
OSC1
OSC2
OSC1
OSC2
RF
PIC16C62X
PIC16C62X
SLEEP
To internal logic
Preliminary
TABLE 9-1:
TABLE 9-2:
Ranges Characterized:
Higher capacitance increases the stability of the oscillator
but also increases the start-up time. These values are for
design guidance only. Since each resonator has its own
characteristics, the user should consult the resonator man-
ufacturer for appropriate values of external components.
Higher capacitance increases the stability of the oscillator
but also increases the start-up time. 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 manu-
facturer for appropriate values of external components.
Mode
Mode
HS
XT
HS
LP
XT
16.0 MHz
2.0 MHz
4.0 MHz
8.0 MHz
455 kHz
200 kHz
100 kHz
10 MHz
20 MHz
Freq
32 kHz
2 MHz
4 MHz
8 MHz
Freq
CAPACITOR SELECTION
FOR CERAMIC RESONATORS
CAPACITOR SELECTION
FOR CRYSTAL OSCILLATOR
PIC16C62X
22 - 100 pF
OSC1(C1)
68 - 100 pF
68 - 150 pF
15 - 68 pF
15 - 68 pF
10 - 68 pF
10 - 22 pF
OSC1(C1)
15 - 30 pF
15 - 30 pF
15 - 30 pF
15 - 30 pF
15 - 30 pF
15 - 30 pF
DS30235G-page 47
150 - 200 pF
22 - 100 pF
68 - 100 pF
OSC2(C2)
15 - 68 pF
15 - 68 pF
10 - 68 pF
10 - 22 pF
OSC2(C2)
15 - 30 pF
15 - 30 pF
15 - 30 pF
15 - 30 pF
15 - 30 pF
15 - 30 pF