PIC16F870SLASHP datasheet(91/156 Pages) MICROCHIP

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Preliminary

DS30569A-page 91

PIC16F870/871

11.2

Oscillator Configurations

11.2.1

OSCILLATOR TYPES

The PIC16F870/871 can be operated in four different

oscillator modes. The user can program two configura-

tion bits (FOSC1 and FOSC0) to select one of these

four modes:

• LP

Low Power Crystal

• XT

Crystal/Resonator

• HS

High Speed Crystal/Resonator

• RC

Resistor/Capacitor

11.2.2

CRYSTAL OSCILLATOR/CERAMIC

RESONATORS

In XT, LP or HS modes, a crystal or ceramic resonator

is connected to the OSC1/CLKIN and OSC2/CLKOUT

pins

establish

oscillation

(Figure 11-1).

The

PIC16F870/871 oscillator design requires the use of a

parallel cut crystal. Use of a series cut crystal may give

a frequency out of the crystal manufacturers specifica-

tions. When in XT, LP or HS modes, the device can

have an external clock source to drive the OSC1/

CLKIN pin (Figure 11-2).

FIGURE 11-1: CRYSTAL/CERAMIC

RESONATOR OPERATION

(HS, XT OR LP

OSC CONFIGURATION)

FIGURE 11-2: EXTERNAL CLOCK INPUT

OPERATION (HS, XT OR LP

OSC CONFIGURATION)

TABLE 11-1:

CERAMIC RESONATORS

Note 1: See Table 11-1 and Table 11-2 for rec-

ommended values of C1 and C2.

2: A series resistor (RS) may be required

for AT strip cut crystals.

3: RF varies with the crystal chosen.

C1(1)

C2(1)

XTAL

OSC2

OSC1

RF(3)

SLEEP

logic

PIC16F870/871

RS(2)

internal

OSC1

OSC2

Open

Clock from

ext. system

PIC16F870/871

Ranges Tested:

Mode

Freq

OSC1

OSC2

455 kHz

2.0 MHz

4.0 MHz

68 - 100 pF

15 - 68 pF

68 - 100 pF

15 - 68 pF

8.0 MHz

16.0 MHz

10 - 68 pF

10 - 22 pF

10 - 68 pF

10 - 22 pF

These values are for design guidance only. See

notes at bottom of page.

Resonators Used:

455 kHz

Panasonic EFO-A455K04B

± 0.3%

2.0 MHz

Murata Erie CSA2.00MG

± 0.5%

4.0 MHz

Murata Erie CSA4.00MG

± 0.5%

8.0 MHz

Murata Erie CSA8.00MT

± 0.5%

16.0 MHz

Murata Erie CSA16.00MX

± 0.5%

All resonators used did not have built-in capacitors.

PIC16F870/P Datasheet(PDF) 91 Page - Microchip Technology

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