PIC18F242 MICROCHIP [Microchip Technology], PIC18F242 Datasheet - Page 25

• Manufacturer Part Number: PIC18F242
• Description: 28/40-pin High Performance, Enhanced FLASH Microcontrollers with 10-Bit A/D
• Manufacturer: MICROCHIP [Microchip Technology]

If the main oscillator is configured for HS-PLL mode, an
oscillator start-up time (T
time-out (T
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 oscillator for
HS-PLL mode is shown in Figure 2-10.
FIGURE 2-10:
If the main oscillator is configured in the RC, RCIO, EC
or ECIO modes, there is no oscillator start-up time-out.
Operation will resume after eight cycles of the main
oscillator have been counted. A timing diagram, indi-
cating the transition from the Timer1 oscillator to the
main oscillator for RC, RCIO, EC and ECIO modes, is
shown in Figure 2-11.
FIGURE 2-11:
© 2006 Microchip Technology Inc.
Program Counter
Internal System
Program Counter
Note 1: T
(OSCCON<0>)
Note 1: RC Oscillator mode assumed.
Internal System
(OSCCON<0>)
PLL Clock
T1OSI
OSC1
OSC2
Clock
T1OSI
OSC1
OSC2
Input
Clock
SCS
SCS
OST
PLL
= 1024 T
) will occur. The PLL time-out is typically
Q4
PC
Q3
OSC
TIMING FOR TRANSITION BETWEEN TIMER1 AND OSC1 (HS WITH PLL)
TIMING FOR TRANSITION BETWEEN TIMER1 AND OSC1 (RC, EC)
(drawing not to scale).
Q1
OST
T
OST
) plus an additional PLL
PC
Q4
T
PLL
Q1
PC + 2
T
OSC
1
T
1
OSC
T
T
2
1
2
P
3
3
PC + 2
T
SCS
4
4
T
T
T
1
SCS
P
5
5
6
6
7
7
Q1 Q2 Q3 Q4
8
8
Q1 Q2 Q3
PIC18FXX2
Q4 Q1 Q2 Q3
Q1 Q2
DS39564C-page 23
PC + 4
PC + 4
Q3
Q4
Q4