Microchip Technology AC164139 Data Sheet

 2010 Microchip Technology Inc.

DS39969B-page 141

The oscillator system for PIC24FJ256DA210 family
devices has the following features:
• A total of four external and internal oscillator options 

as clock sources, providing 11 different clock modes

• An on-chip PLL block to boost internal operating 

frequency on select internal and external oscillator 
sources, and to provide a precise clock source for 
peripherals, such as USB and graphics

• Software controllable switching between various 

clock sources

• Software controllable postscaler for selective 

clocking of CPU for system power savings

• A Fail-Safe Clock Monitor (FSCM) that detects 

clock failure and permits safe application recovery 
or shutdown

• A separate and independently configurable system 

clock output for synchronizing external hardware

A simplified diagram of the oscillator system is shown
in Figure 8-1.

This data sheet summarizes the features
of this group of PIC24F devices. It is not
intended to be a comprehensive reference
source. For more information, refer to the
“PIC24F Family Reference Manual”,
Section 6. “Oscillator” (DS39700). The
information in this data sheet supersedes
the information in the FRM.

Refer to Figure 8-2 for more information on the 96 MHz PLL block.

SOSCEN

Enable

Oscillator

SOSCO

SOSCI

Clock Source Option 

for Other Modules

OSCI

OSCO

XT, HS, EC

CPU

Peripherals

P

ostsc

aler

CLKDIV<10:8>

WDT

8 MHz

FRCDIV

31 kHz (nominal)

FRC

Oscillator

LPRC

Oscillator

SOSC

LPRC

Fail-Safe

Clock

Monitor

CLKDIV<14:12>

FRC

CLKO

(nominal)

XTPLL, HSPLL

ECPLL,FRCPLL

8 MHz/

4 MHz

PLLDIV<2:0>

CPDIV<1:0>

48 MHz USB Clock

Reference Clock

Generator

REFO

REFOCON<15:8>

LPFRC

P

o

stscale

r

GCLKDIV<6:0>

PLL and

DIV

1/16

48/96 MHz Clock for Graphics Controller Module

Clock for Display Interface