PIC16LF1824T39A_12 Datasheet, PDF (54/418 Pages) Microchip Technology – 20-Pin Flash Microcontrollers with XLP Technology

PIC16LF1824T39A
5.2.1.6 External RC Mode
The external Resistor-Capacitor (RC) modes support
the use of an external RC circuit. This allows the
designer maximum flexibility in frequency choice while
keeping costs to a minimum when clock accuracy is not
required.
The RC circuit connects to OSC1. OSC2/CLKOUT is
available for general purpose I/O or CLKOUT. The
function of the OSC2/CLKOUT pin is determined by the
state of the CLKOUTEN bit in Configuration Word 1.
Figure 5-6 shows the external RC mode connections.
FIGURE 5-6:
EXTERNAL RC MODES
VDD
REXT
CEXT
VSS
FOSC/4 or I/O⁽¹⁾
PIC^® MCU
OSC1/CLKIN
OSC2/CLKOUT
Internal
Clock
Recommended values: 10 k  REXT  100 k, <3V
3 k  REXT  100 k, 3-5V
CEXT > 20 pF, 2-5V
Note 1: Output depends upon CLKOUTEN bit of the
Configuration Word 1.
The RC oscillator frequency is a function of the supply
voltage, the resistor (REXT) and capacitor (CEXT) values
and the operating temperature. Other factors affecting
the oscillator frequency are:
• threshold voltage variation
• component tolerances
• packaging variations in capacitance
The user also needs to take into account variation due
to tolerance of external RC components used.
5.2.2 INTERNAL CLOCK SOURCES
The device may be configured to use the internal
oscillator block as the system clock by performing one
of the following actions:
• Program the FOSC<2:0> bits in Configuration
Word 1 to select the INTOSC clock source, which
will be used as the default system clock upon a
device Reset.
• Write the SCS<1:0> bits in the OSCCON register
to switch the system clock source to the internal
oscillator during run-time. See Section 5.3
“Clock Switching”for more information.
In INTOSC mode, OSC1/CLKIN is available for general
purpose I/O. OSC2/CLKOUT is available for general
purpose I/O or CLKOUT.
The function of the OSC2/CLKOUT pin is determined
by the state of the CLKOUTEN bit in Configuration
Word 1.
The internal oscillator block has two independent
oscillators and a dedicated Phase-Locked Loop,
HFPLL that can produce one of three internal system
clock sources.
1. The HFINTOSC (High-Frequency Internal
Oscillator) is factory calibrated and operates at
16 MHz. The HFINTOSC source is generated
from the 500 kHz MFINTOSC source and the
dedicated Phase-Locked Loop, HFPLL. The
frequency of the HFINTOSC can be
user-adjusted via software using the OSCTUNE
register (Register 5-3).
2. The MFINTOSC (Medium-Frequency Internal
Oscillator) is factory calibrated and operates at
500 kHz. The frequency of the MFINTOSC can
be user-adjusted via software using the
OSCTUNE register (Register 5-3).
3. The LFINTOSC (Low-Frequency Internal
Oscillator) is uncalibrated and operates at
31 kHz.
DS41657A-page 54
Preliminary
 2012 Microchip Technology Inc.