PIC16LF1507 Datasheet, PDF (50/266 Pages) Microchip Technology – 20-Pin Flash, 8-Bit Microcontrollers

PIC16(L)F1507
5.3 Clock Switching
The system clock source can be switched between
external and internal clock sources via software using
the System Clock Select (SCS) bits of the OSCCON
register. The following clock sources can be selected
using the SCS bits:
• Default system oscillator determined by FOSC
bits in Configuration Words
• Internal Oscillator Block (INTOSC)
5.3.1
SYSTEM CLOCK SELECT (SCS)
BITS
The System Clock Select (SCS) bits of the OSCCON
register selects the system clock source that is used for
the CPU and peripherals.
• When the SCS bits of the OSCCON register = 00,
the system clock source is determined by value of
the FOSC<1:0> bits in the Configuration Words.
• When the SCS bits of the OSCCON register = 1x,
the system clock source is chosen by the internal
oscillator frequency selected by the IRCF<3:0>
bits of the OSCCON register. After a Reset, the
SCS bits of the OSCCON register are always
cleared.
When switching between clock sources, a delay is
required to allow the new clock to stabilize. These oscil-
lator delays are shown in Table 5-2.
TABLE 5-1: OSCILLATOR SWITCHING DELAYS
Switch From
Switch To
Frequency
Sleep/POR
Sleep/POR
LFINTOSC
Any clock source
Any clock source
LFINTOSC
HFINTOSC
EC
EC
HFINTOSC
LFINTOSC
31 kHz
31.25 kHz-16 MHz
DC – 20 MHz
DC – 20 MHz
31.25 kHz-16 MHz
31 kHz
Oscillator Delay
Oscillator Warm-up Delay (TWARM)
2 cycles
1 cycle of each
2 s (typical)
1 cycle of each
 2011 Microchip Technology Inc.
Preliminary
DS41586A-page 50