PIC16F876ATISLASHML datasheet(147/234 Pages) MICROCHIP

147 / 234 page

 2003 Microchip Technology Inc.

DS39582B-page 145

PIC16F87XA

14.2

Oscillator Configurations

14.2.1

OSCILLATOR TYPES

The PIC16F87XA 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

14.2.2

CRYSTAL OSCILLATOR/CERAMIC

RESONATORS

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

is connected to the OSC1/CLKI and OSC2/CLKO pins

to establish oscillation (Figure 14-1). The PIC16F87XA

oscillator design requires the use of a parallel cut crys-

tal. Use of a series cut crystal may give a frequency out

of the crystal manufacturer’s specifications. When in

XT, LP or HS modes, the device can have an external

clock source to drive the OSC1/CLKI pin (Figure 14-2).

FIGURE 14-1:

CRYSTAL/CERAMIC

RESONATOR OPERATION

(HS, XT OR LP

OSC CONFIGURATION)

FIGURE 14-2:

EXTERNAL CLOCK INPUT

OPERATION (HS, XT OR

LP OSC CONFIGURATION)

TABLE 14-1:

CERAMIC RESONATORS

Note 1: See Table 14-1 and Table 14-2 for recommended

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

PIC16F87XA

(2)

Internal

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 following Table 14-2.

Resonators Used:

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.

OSC1

OSC2

Open

Clock from

Ext. System

PIC16F87XA

PIC16F876ATI/ML Datasheet(PDF) 147 Page - Microchip Technology

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