Datasheet
2013-2014 Microchip Technology Inc. DS70000689D-page 143
dsPIC33EPXXXGM3XX/6XX/7XX
9.0 OSCILLATOR CONFIGURATION
The dsPIC33EPXXXGM3XX/6XX/7XX oscillator system
provides:
• On-chip Phase-Locked Loop (PLL) to boost
internal operating frequency on select internal and
external oscillator sources
• On-the-fly clock switching between various clock
sources
• Doze mode for system power savings
• Fail-Safe Clock Monitor (FSCM) that detects clock
failure and permits safe application recovery or
shutdown
• Configuration bits for clock source selection
A simplified diagram of the oscillator system is shown
in Figure 9-1.
FIGURE 9-1: OSCILLATOR SYSTEM DIAGRAM
Note 1: This data sheet summarizes the features
of the dsPIC33EPXXXGM3XX/6XX/7XX
family of devices. It is not intended to be a
comprehensive reference source. To
complement the information in this data
sheet, refer to the “dsPIC33/PIC24 Fam-
ily Reference Manual”, “Oscillator”
(DS70580), which is available from the
Microchip web site (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 9-2 for PLL and FVCO details.
2: If the oscillator is used with XT or HS modes, an external parallel resistor with the value of 1 M 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.
XTPLL, HSPLL,
XT, HS, EC
FRCDIV<2:0>
WDT, PWRT,
FRCDIVN
FRCDIV16
ECPLL, FRCPLL
NOSC<2:0> FNOSC<2:0>
Reset
FRC
Oscillator
DOZE<2:0>
S3
S1
S2
S1/S3
S7
S6
FRC
LPRC
S0
S5
÷ 16
Clock Switch
S7
Clock Fail
TUN<5:0>
PLL
(1)
FCY
(3)
FOSC
FRCDIV
DOZE
FSCM
POSCCLK
FRCCLK
F
VCO
(1)
OSC2
OSC1
Primary Oscillator
POSCMD<1:0>
FP
(3)
÷ N
ROSEL RODIV<3:0>
REFCLKO
POSCCLK
RPn
F
OSC
Reference Clock Generation
S4
SOSCO
SOSCI
Secondary Oscillator
SOSC
Timer1
LPRC
Oscillator
÷ 2