Datasheet

© 2009-2012 Microchip Technology Inc. Preliminary DS70616F-page 177
dsPIC33EPXXX(GP/MC/MU)806/810/814 and PIC24EPXXX(GP/GU)810/814
9.0 OSCILLATOR CONFIGURATION
The oscillator system provides:
• Four external and internal oscillator options
• Auxiliary oscillator that provides clock source to
the USB module (if available)
• On-chip Phase-Locked Loop (PLL) to boost inter-
nal 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
• Nonvolatile 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 dsPIC33EPXXX(GP/MC/MU)806/
810/814 and PIC24EPXXX(GP/GU)810/
814 families of devices. It is not intended
to be a comprehensive reference source.
To complement the information in this
data sheet, refer to Section 7. “Oscilla-
tor” (DS70580) of the “dsPIC33E/
PIC24E Family Reference Manual”,
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 MΩmust be connected.
3: See Figure 9-3 for APLL details.
Secondary Oscillator (SOSC)
LPOSCEN
SOSCO
SOSCI
Timer1
XTPLL, HSPLL,
XT, HS, EC
FRCDIV<2:0>
WDT, PWRT,
FRCDIVN
S
OSC
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
FSCM
ACLK
POSCCLK
Auxiliary Oscillator
SELACLK
USB
FVCO
(1)
ENAPLL
ASRCSEL
ENAPLL
APLL
(3)
POSCCLK
FRCCLK
F
VCO
(1)
÷N
APLLPOST<2:0>
FRCCLK
FRCSEL
OSC2
OSC1
Primary Oscillator (P
OSC)
R
(2)
POSCMD<1:0>
FP
FAVCO
÷N
ROSEL
RODIV<3:0>
REFCLKO
POSCCLK
RPn
F
OSC
Reference Clock Generation
Auxiliary Clock Generation
(dsPIC33EPXXMU8XX and
PIC24EPXXXGU8XX devices only)