PIC32MX1XX Datasheet, PDF (221/320 Pages) Microchip Technology – 32-bit Microcontrollers (up to 128 KB Flash and 32 KB SRAM) with Audio and Graphics Interfaces, USB, and Advanced Analog

25.0 POWER-SAVING FEATURES
Note 1: This data sheet summarizes the features
of the PIC32MX1XX/2XX family of
devices. It is not intended to be a
comprehensive reference source. To
complement the information in this data
sheet, refer to Section 10. “Power-
Saving Features” (DS61130) in the
“PIC32 Family Reference Manual”, 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
Section 4.0 “Memory Organization” in
this data sheet for device-specific register
and bit information.
This section describes power-saving features for the
PIC32MX1XX/2XX. The PIC32 devices offer a total of
nine methods and modes, organized into two
categories, that allow the user to balance power
consumption with device performance. In all of the
methods and modes described in this section, power-
saving is controlled by software.
25.1 Power Saving with CPU Running
When the CPU is running, power consumption can be
controlled by reducing the CPU clock frequency,
lowering the PBCLK and by individually disabling
modules. These methods are grouped into the
following categories:
• FRC Run mode: the CPU is clocked from the FRC
clock source with or without postscalers.
• LPRC Run mode: the CPU is clocked from the
LPRC clock source.
• SOSC Run mode: the CPU is clocked from the
SOSC clock source.
In addition, the Peripheral Bus Scaling mode is available
where peripherals are clocked at the programmable
fraction of the CPU clock (SYSCLK).
25.2 CPU Halted Methods
The device supports two power-saving modes, Sleep
and Idle, both of which Halt the clock to the CPU. These
modes operate with all clock sources, as listed below:
• POSC Idle mode: the system clock is derived from
the POSC. The system clock source continues to
operate. Peripherals continue to operate, but can
optionally be individually disabled.
• FRC Idle mode: the system clock is derived from
the FRC with or without postscalers. Peripherals
continue to operate, but can optionally be
individually disabled.
• SOSC Idle mode: the system clock is derived from
the SOSC. Peripherals continue to operate, but
can optionally be individually disabled.
PIC32MX1XX/2XX
• LPRC Idle mode: the system clock is derived from
the LPRC. Peripherals continue to operate, but
can optionally be individually disabled. This is the
lowest power mode for the device with a clock
running.
• Sleep mode: the CPU, the system clock source
and any peripherals that operate from the system
clock source are Halted. Some peripherals can
operate in Sleep using specific clock sources.
This is the lowest power mode for the device.
25.3 Power-Saving Operation
Peripherals and the CPU can be Halted or disabled to
further reduce power consumption.
25.3.1 SLEEP MODE
Sleep mode has the lowest power consumption of the
device power-saving operating modes. The CPU and
most peripherals are Halted. Select peripherals can
continue to operate in Sleep mode and can be used to
wake the device from Sleep. See the individual
peripheral module sections for descriptions of
behavior in Sleep.
Sleep mode includes the following characteristics:
• The CPU is Halted.
• The system clock source is typically shutdown.
See Section 25.3.3 “Peripheral Bus Scaling
Method” for specific information.
• There can be a wake-up delay based on the
oscillator selection.
• The Fail-Safe Clock Monitor (FSCM) does not
operate during Sleep mode.
• The BOR circuit remains operative during Sleep
mode.
• The WDT, if enabled, is not automatically cleared
prior to entering Sleep mode.
• Some peripherals can continue to operate at
limited functionality in Sleep mode. These
peripherals include I/O pins that detect a change
in the input signal, WDT, ADC, UART and
peripherals that use an external clock input or the
internal LPRC oscillator (e.g., RTCC, Timer1 and
Input Capture).
• I/O pins continue to sink or source current in the
same manner as they do when the device is not in
Sleep.
• The USB module can override the disabling of the
Posc or FRC. Refer to the USB section for
specific details.
• Modules can be individually disabled by software
prior to entering Sleep in order to further reduce
consumption.
© 2011-2012 Microchip Technology Inc.
Preliminary
DS61168D-page 221