Datasheet
© 2007-2011 Microchip Technology Inc. DS70264E-page 97
dsPIC33FJ12GP201/202
8.0 OSCILLATOR
CONFIGURATION
The dsPIC33FJ12GP201/202 oscillator system
provides:
• External and internal oscillator options as clock
sources
• An on-chip 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
• An Oscillator 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: dsPIC33FJ12GP201/202 OSCILLATOR SYSTEM DIAGRAM
Note 1: This data sheet summarizes the features
of the dsPIC33FJ12GP201/202 family of
devices. It is not intended to be a compre-
hensive reference source. To comple-
ment the information in this data sheet,
refer to Section 7. “Oscillator”
(DS70186) of the “dsPIC33F/PIC24H
Family Reference Manual”, which is
available from the Microchip website
(www.microchip.com).
2: 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: See Figure 8-2 for PLL details.
2: If the Oscillator is used with XT or HS modes, an external parallel resistor with the value of 1 MW must be connected.
3: 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
CY and FP are used interchangeably, except in the case of Doze mode. FP and FCY will be different when Doze mode is used with a
Doze ratio of 1:2 or lower.
Secondary Oscillator
LPOSCEN
SOSCO
SOSCI
Timer 1
XTPLL, HSPLL,
XT, HS, EC
FRCDIV<2:0>
WDT, PWRT,
FSCM
FRCDIVN
SOSC
FRCDIV16
ECPLL, 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>
PLL
(1)
FCY
FOSC
FRCDIV
DOZE
OSC2
OSC1
Primary Oscillator
R
(2)
POSCMD<1:0>
FP