PIC12F519-ESLASHMS datasheet(39/88 Pages) MICROCHIP

39 / 88 page

Preliminary

DS41319A-page 37

PIC12F519

8.2

Oscillator Configurations

8.2.1

OSCILLATOR TYPES

The PIC12F519 device can be operated in up to four

different oscillator modes. The user can program using

the Configuration bits (FOSC<1:0>), to select one of

these modes:

• LP:

Low-Power Crystal

• XT:

Crystal/Resonator

• INTRC: Internal 4 MHz or 8 MHz Oscillator

• EXTRC: External Resistor/Capacitor

8.2.2

CRYSTAL OSCILLATOR/CERAMIC

RESONATORS

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

connected to the (RB5)/OSC1/(CLKIN) and (RB4)/OSC2

pins to establish oscillation (Figure 8-1). The PIC12F519

oscillator designs require the use of a parallel cut crystal.

Use of a series cut crystal may give a frequency out of the

crystal manufacturers specifications. When in XT or LP

modes, the device can have an external clock source

drive the (RB5)/OSC1/CLKIN pin (Figure 8-2). When the

part is used in this fashion, the output drive levels on the

OSC2 pin are very weak. This pin should be left open and

unloaded. Also when using this mode, the external clock

should observe the frequency limits for the clock mode

chosen (XT or LP).

FIGURE 8-1:

CRYSTAL OPERATION

(OR CERAMIC

RESONATOR)

(XT OR LP OSC

CONFIGURATION)

FIGURE 8-2:

EXTERNAL CLOCK INPUT

OPERATION (XT OR LP

OSC CONFIGURATION)

TABLE 8-1:

CAPACITOR SELECTION FOR

CERAMIC RESONATORS

TABLE 8-2:

CAPACITOR SELECTION FOR

CRYSTAL OSCILLATOR –

PIC12F519(2)

Note 1: The user should verify that the device

oscillator

starts

and

performs

expected. Adjusting the loading capacitor

values and/or the Oscillator mode may

be required.

Note 1:

See Capacitor Selection tables for

recommended values of C1 and C2.

A series resistor (RS) may be required for AT

strip cut crystals.

RF approx. value = 10 M

Ω.

C1(1)

C2(1)

XTAL

OSC2

OSC1

RF(3)

Sleep

To internal

logic

RS(2)

PIC12F519

Osc

Type

Resonator

Freq.

Cap. Range

4.0 MHz

30 pF

Note:

Component values shown are for design

guidance only. Since each resonator has

its own characteristics, the user should

consult the resonator manufacturer for

appropriate values of external compo-

nents.

Osc

Type

Resonator

Freq.

Cap.Range

Cap. Range

32 kHz(1)

15 pF

200 kHz

1 MHz

4 MHz

47-68 pF

15 pF

47-68 pF

15 pF

Note 1: For VDD > 4.5V, C1 = C2

≈ 30 pF is

recommended.

2: Component values shown are for design

guidance only. Rs may be required to

avoid overdriving crystals with low drive

level specification. Since each crystal has

its own characteristics, the user should

consult the crystal manufacturer for

appropriate values of external compo-

nents.

Clock from

ext. system

OSC1

OSC2

Open

PIC12F519

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