PIC16F1825T-ESS datasheet(60/448 Pages) MICROCHIP

60 / 448 page

PIC16(L)F1825/1829

DS41440C-page 60

 2010-2012 Microchip Technology Inc.

FIGURE 5-6:

EXTERNAL RC MODES

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-Lock Loop, HFPLL

that can produce one of three internal system clock

sources.

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-Lock Loop, HFPLL. The

frequency

the

HFINTOSC

can

user-adjusted via software using the OSCTUNE

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).

The

LFINTOSC

(Low-Frequency

Internal

Oscillator) is uncalibrated and operates at

31 kHz.

OSC2/CLKOUT

CEXT

REXT

PIC® MCU

OSC1/CLKIN

FOSC/4 or

Internal

Clock

VDD

VSS

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.

I/O(1)

PIC16F1825T-ESS Datasheet(PDF) 60 Page - Microchip Technology

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