PIC16F54T-I/SO 查看數據表（PDF） - Microchip Technology

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PIC16F54T-I/SO

Flash-Based, 8-Bit CMOS Microcontroller Series

Microchip Technology 

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:

• XT:

• HS:

• RC:

Low-power Crystal

Crystal/Resonator

High-speed Crystal/Resonator

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 to 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:

C1(1)

CRYSTAL/CERAMIC

RESONATOR OPERATION

(HS, XT OR LP OSC

CONFIGURATION)

OSC1

PIC16F5X

XTAL

OSC2

RS(2)

C2(1)

RF(3)

Sleep

To internal

logic

Note 1:

2:

See Capacitor Selection tables for

recommended values of C1 and C2.

A series resistor (RS) may be required.

3: RF varies with the Oscillator mode chosen

(approx. value = 10 MΩ).

FIGURE 4-2:

Clock from

ext. system

Open

EXTERNAL CLOCK INPUT

OPERATION (HS, XT OR LP

OSC CONFIGURATION)

OSC1

PIC16F5X

OSC2

PIC16F5X

TABLE 4-1: CAPACITOR SELECTION FOR

CERAMIC RESONATORS

Osc Resonator Cap. Range Cap. Range

Type

Freq.

C1

C2

XT

455 kHz 68-100 pF 68-100 pF

2.0 MHz 15-33 pF

15-33 pF

4.0 MHz 10-22 pF

10-22 pF

HS

8.0 MHz 10-22 pF

10-22 pF

16.0 MHz

10 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.

TABLE 4-2: CAPACITOR SELECTION FOR

CRYSTAL OSCILLATOR

Osc

Type

Crystal

Freq.

Cap.Range Cap. Range

C1

C2

LP

32 kHz(1)

15 pF

15 pF

XT

100 kHz 15-30 pF 200-300 pF

200 kHz 15-30 pF 100-200 pF

455 kHz 15-30 pF 15-100 pF

1 MHz

15-30 pF

15-30 pF

2 MHz

15 pF

15 pF

4 MHz

15 pF

15 pF

HS

4 MHz

15 pF

8 MHz

15 pF

20 MHz

15 pF

15 pF

15 pF

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 as

expected. Adjusting the loading capacitor

values and/or the Oscillator mode may be

required.

© 2007 Microchip Technology Inc.

DS41213D-page 21

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