
2004 Microchip Technology Inc.
DS30491C-page 29
PIC18F6585/8585/6680/8680
If the main oscillator is configured for HS mode with
PLL active, an oscillator start-up time (TOST) plus an
additional PLL time-out (TPLL) will occur. The PLL time-
out is typically 2 ms and allows the PLL to lock to the
main oscillator frequency. A timing diagram, indicating
the transition from the Timer1 oscillator to the main
If the main oscillator is configured for EC mode with PLL
active, only the PLL time-out (TPLL) will occur. The PLL
time-out is typically 2 ms and allows the PLL to lock to
the main oscillator frequency. A timing diagram, indicat-
ing the transition from the Timer1 oscillator to the main
FIGURE 2-10:
TIMING FOR TRANSITION BETWEEN TIMER1 AND OSC1
(HS WITH PLL ACTIVE, SCS1 = 1)
FIGURE 2-11:
TIMING FOR TRANSITION BETWEEN TIMER1 AND OSC1
(EC WITH PLL ACTIVE, SCS1 = 1)
Q4
Q1
Q2 Q3
Q4
Q1 Q2
OSC1
Internal System
SCS
(OSCCON<0>)
Program Counter
PC
PC + 2
Note:
TOST = 1024 TOSC (drawing not to scale).
T1OSI
Clock
TOST
Q3
PC + 4
TPLL
TOSC
TT1P
TSCS
Q4
PLL Clock
Input
1
2
3
4
56
78
Q4
Q1
Q2 Q3
Q4
Q1 Q2
OSC1
Internal System
SCS
(OSCCON<0>)
Program Counter
PC
PC + 2
T1OSI
Clock
Q3
PC + 4
TPLL
TOSC
TT1P
TSCS
Q4
PLL Clock
Input
1
2
3
4
56
78