16F876 Microchip Technology, 16F876 Datasheet - Page 123

• Manufacturer Part Number: 16F876
• Description: 28/40-pin 8-Bit CMOS FLASH Microcontrollers
• Manufacturer: Microchip Technology

12.2
12.2.1
The PIC16F87X can be operated in four different oscil-
lator modes. The user can program two configuration
bits (FOSC1 and FOSC0) to select one of these four
modes:
• LP
• XT
• HS
• RC
12.2.2
In XT, LP or HS modes, a crystal or ceramic resonator
is connected to the OSC1/CLKIN and OSC2/CLKOUT
pins to establish oscillation (Figure 12-1).
PIC16F87X oscillator design requires the use of a par-
allel cut crystal. Use of a series cut crystal may give a
frequency out of the crystal manufacturers specifica-
tions. When in XT, LP or HS modes, the device can
have an external clock source to drive the OSC1/
CLKIN pin (Figure 12-2).
FIGURE 12-1: CRYSTAL/CERAMIC
FIGURE 12-2: EXTERNAL CLOCK INPUT
1999 Microchip Technology Inc.
Clock from
ext. system
Note 1: See Table 12-1 and Table 12-2 for rec-
C1
C2
Oscillator Configurations
CRYSTAL OSCILLATOR/CERAMIC
RESONATORS
OSCILLATOR TYPES
(1)
(1)
2: A series resistor (RS) may be required
3: RF varies with the crystal chosen.
Low Power Crystal
Crystal/Resonator
High Speed Crystal/Resonator
Resistor/Capacitor
ommended values of C1 and C2.
for AT strip cut crystals.
XTAL
RS
Open
(2)
RESONATOR OPERATION
(HS, XT OR LP
OSC CONFIGURATION)
OPERATION (HS, XT OR LP
OSC CONFIGURATION)
OSC1
OSC2
OSC1
OSC2
RF
(3)
PIC16F87X
PIC16F87X
SLEEP
To
internal
logic
The
TABLE 12-1:
16.0 MHz
2.0 MHz
4.0 MHz
8.0 MHz
455 kHz
Mode
HS
XT
All resonators used did not have built-in capacitors.
These values are for design guidance only. See
notes at bottom of page.
Panasonic EFO-A455K04B
Murata Erie CSA16.00MX
16.0 MHz
Murata Erie CSA2.00MG
Murata Erie CSA4.00MG
Murata Erie CSA8.00MT
2.0 MHz
4.0 MHz
8.0 MHz
455 kHz
Freq
Resonators Used:
CERAMIC RESONATORS
Ranges Tested:
PIC16F87X
68 - 100 pF
15 - 68 pF
15 - 68 pF
10 - 68 pF
10 - 22 pF
OSC1
DS30292B-page 123
68 - 100 pF
15 - 68 pF
15 - 68 pF
10 - 68 pF
10 - 22 pF
OSC2
0.3%
0.5%
0.5%
0.5%
0.5%