Microchip Technology MA320002 Data Sheet
© 2011 Microchip Technology Inc.
DS61143H-page 93
PIC32MX3XX/4XX
8.0
OSCILLATOR
CONFIGURATION
CONFIGURATION
The PIC32MX oscillator system has the following
modules and features:
modules and features:
• A total of four external and internal oscillator
options as clock sources
• On-chip PLL (phase-locked loop) with user-
selectable input divider, multiplier and output
divider to boost operating frequency on select
internal and external oscillator sources
divider to boost operating frequency on select
internal and external oscillator sources
• On-chip user-selectable divisor postscaler on
select oscillator sources
• Software-controllable switching between various
clock sources
• A Fail-Safe Clock Monitor (FSCM) that detects
clock failure and permits safe application recovery
or shut down
or shut down
• Dedicated on-chip PLL for USB peripheral
FIGURE 8-1:
PIC32MX3XX/4XX FAMILY CLOCK DIAGRAM
Note 1: This data sheet summarizes the features
of the PIC32MX3XX/4XX family of
devices. It is not intended to be a
comprehensive reference source. To
complement the information in this data
sheet, refer to the “PIC32 Family
Reference Manual”
devices. It is not intended to be a
comprehensive reference source. To
complement the information in this data
sheet, refer to the “PIC32 Family
Reference Manual”
Section 6.
“Oscillator Configuration” (DS61112),
which is available from the Microchip web
site (
which is available from the Microchip web
site (
www.microchip.com/PIC32
).
2: Some registers and associated bits
described in this section may not be
available on all devices. Refer to
available on all devices. Refer to
in
this data sheet for device-specific register
and bit information.
and bit information.
Timer1, RTCC
Clock Control Logic
Fail-Safe
Clock
Monitor
FSCM INT
FSCM Event
COSC<2:0>
NOSC<2:0>
OSWEN
FSCMEN<1:0>
PLL
Secondary Oscillator (S
OSC
)
SOSCEN and FSOSCEN
SOSCO
SOSCI
Primary Oscillator (P
OSC
)
XTPLL, HSPLL,
XT, HS, EC
CPU and Select Peripherals
Peripherals
FRCDIV<2:0>
WDT, PWRT
8 MHz typical
FRC
31.25 kHz typical
FRC
Oscillator
LPRC
Oscillator
S
OSC
LPRC
FRCDIV
ECPLL, FRCPLL
TUN<5:0>
div 16
Postscaler
FPLLIDIV<2:0>
PBDIV<1:0>
FRC/16
Postscaler
PLL Multiplier
COSC<2:0>
F
IN
div x
div y
PLL Output Divider
PLLODIV<2:0>
PLL Input Divider
div x
32.768 kHz
PLLMULT<2:0>
PBCLK
UF
IN
= 4 MHz
PLL x24
USB Clock (48 MHz)
div 2
UPLLEN
UFRCEN
div x
UPLLIDIV<2:0>
UF
IN
4 MHz
≤ F
IN
≤ 5 MHz
C1
(3)
C2
(3)
XTAL
R
S
(1)
Enable
Notes:
1.
A series resistor, R
S
, may be required for AT strip-cut crystals.
2.
The internal feedback resistor, R
F
, is typically in the range of 2 to 10 M
Ω.
3.
Refer to the “PIC32 Family Reference Manual” Section 6. “Oscillator
Configuration” (DS61112) for help determining the best oscillator
components.
Configuration” (DS61112) for help determining the best oscillator
components.
4.
PBCLK out is available on the OSC2 pin in certain clock modes.
OSC2
(4)
OSC1
R
F
(2)
To Internal
Logic
Logic
USB PLL
SYSCLK