PIC16F5X datasheet(23/88 Pages) MICROCHIP

23 / 88 page

DS41213D-page 21

PIC16F5X

4.0

OSCILLATOR

CONFIGURATIONS

4.1

Oscillator Types

The PIC16F5X devices can be operated in four differ-

ent oscillator modes. The user can program two Con-

figuration bits (FOSC1:FOSC0) to select one of these

four modes:

• LP:

Low-power Crystal

• XT:

Crystal/Resonator

• HS:

High-speed Crystal/Resonator

• RC:

Resistor/Capacitor

4.2

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 4-1).

The

PIC16F5X oscillator design requires the use of a

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

a frequency outside of the crystal manufacturers

specifications. When in XT, LP or HS modes, the

device can have an external clock source drive the

OSC1/CLKIN pin (Figure 4-2).

FIGURE 4-1:

CRYSTAL/CERAMIC

RESONATOR OPERATION

(HS, XT OR LP OSC

CONFIGURATION)

FIGURE 4-2:

EXTERNAL CLOCK INPUT

OPERATION (HS, XT OR LP

OSC CONFIGURATION)

TABLE 4-1:

CAPACITOR SELECTION FOR

CERAMIC RESONATORS

TABLE 4-2:

CAPACITOR SELECTION FOR

CRYSTAL OSCILLATOR

Note

See Capacitor Selection tables for

recommended values of C1 and C2.

A series resistor (RS) may be required.

RF varies with the Oscillator mode chosen

(approx. value = 10 M

Ω).

C1(1)

C2(1)

XTAL

OSC2

OSC1

RF(3)

Sleep

To internal

logic

RS(2)

PIC16F5X

Clock from

ext. system

OSC1

OSC2

Open

PIC16F5X

Osc

Type

Resonator

Freq.

Cap. Range

455 kHz

2.0 MHz

4.0 MHz

68-100 pF

15-33 pF

10-22 pF

68-100 pF

15-33 pF

10-22 pF

8.0 MHz

16.0 MHz

10-22 pF

10 pF

10-22 pF

10 pF

These values are for design guidance only. Since

each resonator has its own characteristics, the user

should consult the resonator manufacturer for

appropriate values of external components.

Osc

Type

Crystal

Freq.

Cap.Range

Cap. Range

32 kHz(1)

15 pF

100 kHz

200 kHz

455 kHz

1MHz

2MHz

4MHz

15-30 pF

15 pF

200-300 pF

100-200 pF

15-100 pF

15-30 pF

15 pF

4 MHz

8MHz

20 MHz

15 pF

Note 1:

For VDD > 4.5V, C1 = C2

≈ 30 pF is

recommended.

These values are for design guidance only. Rs may

be required in HS mode, as well as XT mode, to

avoid overdriving crystals with low drive level specifi-

cations. Since each crystal has its own characteris-

tics, the user should consult the crystal manufacturer

for appropriate values of external components.

Note 1: This device has been designed to perform

to the parameters of its data sheet. It has

been tested to an electrical specification

designed to determine its conformance

with these parameters. Due to process

differences in the manufacture of this

device, this device may have different

performance

characteristics

than

its

earlier version. These differences may

cause this device to perform differently in

your application than the earlier version of

this device.

2: 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.

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