PIC16F193X Datasheet, PDF (113/418 Pages) Microchip Technology – 28/40/44-Pin Flash-Based, 8-Bit CMOS Microcontrollers with LCD Driver and nanoWatt Technology

8.4.4 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.
Figure 8-5 shows the external RC mode connections.
FIGURE 8-5:
EXTERNAL RC MODES
VDD
REXT
CEXT
VSS
FOSC/4 or
I/O⁽¹⁾
PIC^® MCU
OSC1/CLKIN
OSC2/CLKOUT
Internal
Clock
Recommended values: 10 kΩ ≤ REXT ≤ 100 kΩ, <3V
3 kΩ ≤ REXT ≤ 100 kΩ, 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.
PIC16F193X/LF193X
8.5 Internal Clock Modes
The oscillator module has three independent, internal
oscillators that can be configured or selected as the
system clock source.
1. The HFINTOSC (High-Frequency Internal
Oscillator) is factory calibrated and operates at
16 MHz. The frequency of the HFINTOSC can
be user-adjusted via software using the
OSCTUNE register (Register 8-3).
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 8-3).
3. The LFINTOSC (Low-Frequency Internal
Oscillator) is uncalibrated and operates at
31 kHz.
The system clock speed can be selected via software
using the Internal Oscillator Frequency Select bits
IRCF<2:0> of the OSCCON register.
The system clock can be selected between external or
internal clock sources via the System Clock Selection
(SCS) bits of the OSCCON register. See Section 8.6
“Clock Switching” for more information.
8.5.1 INTOSC MODE
The INTOSC mode configures the internal oscillators
as the system clock source when the device is
programmed using the oscillator selection or the
FOSC<2:0> bits in the Configuration Word Register 1
(CONFIG1).
In INTOSC mode, OSC1/CLKIN is available for general
purpose I/O. OSC2/CLKOUT is available for general
purpose I/O or CLKOUT.
© 2008 Microchip Technology Inc.
Preliminary
DS41364A-page 111