Datasheet

PIC16F818/819
DS39598F-page 42  2001-2013 Microchip Technology Inc.
FIGURE 5-7: BLOCK DIAGRAM OF RA7/OSC1/CLKI PIN
Data
Bus
QD
Q
CK
WR
PORTA
WR
TRISA
Data Latch
TRIS Latch
RD TRISA
RD PORTA
Q
D
Q
CK
DQ
EN
Oscillator
Circuit
RA7/OSC1/CLKI
P
N
VSS
VDD
FOSC = 10x
VDD
Note 1: I/O pins have protection diodes to VDD and VSS.
(FOSC = 011)
FOSC = 10x
From OSC2
V
SS
Schmitt Trigger
Input Buffer