Datasheet
© 2011-2012 Microchip Technology Inc. Preliminary DS39997C-page 101
PIC24FJ16MC101/102 AND PIC24FJ32MC101/102/104
8.0 OSCILLATOR
CONFIGURATION
The PIC24FJ16MC101/102 and PIC24FJ32MC101/
102/104 oscillator system provides:
• External and internal oscillator options as clock
sources
• An on-chip 4x Phase-Locked Loop (PLL) to scale
the internal operating frequency to the required
system clock frequency
• An internal FRC oscillator that can also be used
with the PLL, thereby allowing full-speed
operation without any external clock generation
hardware
• Clock switching between various clock sources
• Programmable clock postscaler for system power
savings
• A Fail-Safe Clock Monitor (FSCM) that detects
clock failure and takes fail-safe measures
• A Clock Control register (OSCCON)
• Nonvolatile Configuration bits for main oscillator
selection
A simplified diagram of the oscillator system is shown
in Figure 8-1.
FIGURE 8-1: OSCILLATOR SYSTEM DIAGRAM
Note 1: This data sheet summarizes the features
of the PIC24FJ16MC101/102 and
PIC24FJ32MC101/102/104 family of
devices. It is not intended to be a
comprehensive reference source. To
complement the information in this data
sheet, refer to Section 6. “Oscillator”
(DS39700) in the “PIC24F Family
Reference Manual”, which is available
from the Microchip web site
(www.microchip.com).
2: It is important to note that the
specifications in Section 26.0 “Electri-
cal Characteristics” of this data sheet,
supercede any specifications that may be
provided in PIC24F Family Reference
Manual sections.
3: Some registers and associated bits
described in this section may not be
available on all devices. Refer to
Section 4.0 “Memory Organization” in
this data sheet for device-specific register
and bit information.
Note 1: If the Oscillator is used with MS or HS modes, an extended parallel resistor with the value of 1 MΩ must be connected.
2: The term F
P refers to the clock source for all peripherals, while FCY refers to the clock source for the CPU. Throughout this document,
F
P and FCY are used interchangeably, except in the case of DOZE mode. FP and FCY are different when DOZE mode is used with a
doze ratio of 1:2 or lower.
Secondary Oscillator (SOSC)
LPOSCEN
SOSCO
SOSCI
Timer 1
MSPLL, ECPLL,
MS, HS, EC
FRCDIV<2:0>
WDT, PWRT, FSCM
FRCDIVN
SOSC
FRCDIV16
FRCPLL
NOSC<2:0> FNOSC<2:0>
Reset
FRC
Oscillator
LPRC
Oscillator
DOZE<2:0>
S3
S1
S2
S1/S3
S7
S6
FRC
LPRC
S0
S5
S4
÷16
Clock Switch
S7
Clock Fail
÷
2
TUN<5:0>
4x PLL
F
CY
(2)
FRCDIV
DOZE
OSC2
OSC1
Primary Oscillator (P
OSC)
R
(1)
POSCMD<1:0>
FP
(2)
Fosc
(To peripherals)