PIC18F258T-I/SP View Datasheet(PDF) - Microchip Technology

Part Name

Description

Manufacturer

PIC18F258T-I/SP

28/40-Pin High-Performance, Enhanced Flash Microcontrollers with CAN Module

Microchip Technology 

2.0 OSCILLATOR

CONFIGURATIONS

2.1 Oscillator Types

The PIC18FXX8 can be operated in one of eight oscil-

lator modes, programmable by three configuration bits

(FOSC2, FOSC1 and FOSC0).

1. LP

2. XT

3. HS

4. HS4

5. RC

6. RCIO

7. EC

8. ECIO

Low-Power Crystal

Crystal/Resonator

High-Speed Crystal/Resonator

High-Speed Crystal/Resonator with

PLL enabled

External Resistor/Capacitor

External Resistor/Capacitor with I/O

pin enabled

External Clock

External Clock with I/O pin enabled

2.2 Crystal Oscillator/Ceramic

Resonators

In XT, LP, HS or HS4 (PLL) Oscillator modes, a crystal

or ceramic resonator is connected to the OSC1 and

OSC2 pins to establish oscillation. Figure 2-1 shows

the pin connections. An external clock source may also

be connected to the OSC1 pin, as shown in Figure 2-3

and Figure 2-4.

The PIC18FXX8 oscillator design requires the use of a

parallel cut crystal.

Note:

Use of a series cut crystal may give a fre-

quency out of the crystal manufacturer’s

specifications.

PIC18FXX8

FIGURE 2-1:

CRYSTAL/CERAMIC

RESONATOR OPERATION

(HS, XT OR LP OSC

CONFIGURATION)

C1(1)

OSC1

XTAL

RF(3)

To

Internal

Logic

RS(2)

C2(1)

OSC2

Sleep

PIC18FXX8

Note 1: See Table 2-1 and Table 2-2 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.

TABLE 2-1: CERAMIC RESONATORS

Ranges Tested:

Mode

Freq

OSC1

OSC2

XT

455 kHz 68-100 pF 68-100 pF

2.0 MHz

15-68 pF 15-68 pF

4.0 MHz

15-68 pF 15-68 pF

HS

8.0 MHz

10-68 pF 10-68 pF

16.0 MHz 10-22 pF 10-22 pF

These values are for design guidance only.

See notes following Table 2-2.

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.

© 2006 Microchip Technology Inc.

DS41159E-page 17

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