PIC16F1459-ESSQTP datasheet(61/418 Pages) MICROCHIP

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 2012 Microchip Technology Inc.

Preliminary

DS41639A-page 61

PIC16(L)F1454/5/9

5.2.1.4

3x PLL or 4x PLL

The oscillator module contains a PLL that can be used

with both external and internal clock sources to provide a

system clock source. By setting the SPLLMULT bit of the

OSCCON register, 3x PLL is selected. By clearing the

SPLLMULT bit of the OSCCON register, 4x PLL is

selected. The input frequency for the PLL must fall within

specifications. See the PLL Clock Timing Specifications in

Section 29.0 “Electrical Specifications”.

The PLL may be enabled for use by one of two methods:

Program the PLLEN bit in Configuration Words

to a ‘1’.

Write the SPLLEN bit in the OSCCON register to

a ‘1’. If the PLLEN bit in Configuration Words is

programmed to a ‘1’, then the value of SPLLEN

is ignored.

5.2.1.5

Secondary Oscillator

The secondary oscillator is a separate crystal oscillator

that is associated with the Timer1 peripheral. It is opti-

mized for timekeeping operations with a 32.768 kHz

crystal connected between the SOSCO and SOSCI

device pins.

The secondary oscillator can be used as an alternate

system clock source and can be selected during

run-time using clock switching. Refer to Section 5.3

“CPU Clock Divider” for more information.

FIGURE 5-5:

QUARTZ CRYSTAL

OPERATION

(SECONDARY

OSCILLATOR)

PLL

HFINTOSC

(MHz)

ECH/HS

(MHz)

System

Clock (MHz)

8 - 12

32 - 48

16, 8

8 - 16

24 - 48

32.768 kHz

SOSCI

To Internal

Logic

PIC® MCU

Crystal

SOSCO

Quartz

Note 1: Quartz

crystal

characteristics

vary

according

type,

package

and

manufacturer. The user should consult the

manufacturer data sheets for specifications

and recommended application.

2: Always verify oscillator performance over

the VDD and temperature range that is

expected for the application.

3: For oscillator design assistance, reference

the following Microchip Applications Notes:

• AN826, “Crystal Oscillator Basics and

Crystal Selection for rfPIC® and PIC®

Devices” (DS00826)

• AN849, “Basic PIC® Oscillator Design”

(DS00849)

• AN943, “Practical PIC® Oscillator

Analysis and Design” (DS00943)

• AN949, “Making Your Oscillator Work”

(DS00949)

• TB097, “Interfacing a Micro Crystal

MS1V-T1K 32.768 kHz Tuning Fork

Crystal to a PIC16F690/SS” (DS91097)

• AN1288, “Design Practices for

Low-Power External Oscillators”

(DS01288)

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