PIC18F45J10T-I/PT(2009) View Datasheet(PDF) - Microchip Technology

Part Name

Description

Manufacturer

PIC18F45J10T-I/PT
(Rev.:2009)

28/40/44-Pin High-Performance, RISC Microcontrollers

Microchip Technology 

PIC18F45J10 FAMILY

3.4 PLL Frequency Multiplier

A Phase Locked Loop (PLL) circuit is provided as an

option for users who want to use a lower frequency

oscillator circuit, or to clock the device up to its highest

rated frequency from a crystal oscillator. This may be

useful for customers who are concerned with EMI due

to high-frequency crystals, or users who require higher

clock speeds from an internal oscillator. For these

reasons, the HSPLL and ECPLL modes are available.

The HSPLL and ECPLL modes provide the ability to

selectively run the device at 4 times the external oscil-

lating source to produce frequencies up to 40 MHz.

The PLL is enabled by setting the PLLEN bit in the

OSCTUNE register (Register 3-1).

FIGURE 3-4:

PLL BLOCK DIAGRAM

HSPLL or ECPLL (CONFIG2L)

PLL Enable (OSCTUNE)

OSC2

HS or EC

OSC1 Mode

FIN

FOUT

Phase

Comparator

Loop

Filter

÷4

VCO

SYSCLK

REGISTER 3-1: OSCTUNE: PLL CONTROL REGISTER

U-0

R/W-0

U-0

U-0

U-0

U-0

U-0

U-0

—

PLLEN(1)

—

—

—

—

—

—

bit 7

bit 0

Legend:

R = Readable bit

-n = Value at POR

W = Writable bit

‘1’ = Bit is set

U = Unimplemented bit, read as ‘0’

‘0’ = Bit is cleared

x = Bit is unknown

bit 7

bit 6

bit 5-0

Unimplemented: Read as ‘0’

PLLEN: Frequency Multiplier PLL Enable bit(1)

1 = PLL enabled

0 = PLL disabled

Unimplemented: Read as ‘0’

Note 1: Available only for ECPLL and HSPLL oscillator configurations; otherwise, this bit is unavailable and reads

as ‘0’.

© 2009 Microchip Technology Inc.

DS39682E-page 29

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