PIC24HJ64GP506-I Datasheet, PDF (133/292 Pages) Microchip Technology – High-Performance, 16-Bit Microcontrollers

PIC24HJXXXGPX06/X08/X10
10.0 POWER-SAVING FEATURES
Note:
This data sheet summarizes the features
of the PIC24HJXXXGPX06/X08/X10 fam-
ily of devices. However, it is not intended
to be a comprehensive reference source.
To complement the information in this data
sheet, refer to the “PIC24H Family Refer-
ence Manual”, Section 9. “Watchdog
Timer and Power-Saving Modes”
(DS70236), which is available from the
Microchip website (www.microchip.com).
The PIC24HJXXXGPX06/X08/X10 devices provide the
ability to manage power consumption by selectively
managing clocking to the CPU and the peripherals. In
general, a lower clock frequency and a reduction in the
number of circuits being clocked constitutes lower con-
sumed power. PIC24HJXXXGPX06/X08/X10 devices
can manage power consumption in four different ways:
• Clock frequency
• Instruction-based Sleep and Idle modes
• Software-controlled Doze mode
• Selective peripheral control in software
Combinations of these methods can be used to selec-
tively tailor an application’s power consumption while
still maintaining critical application features, such as
timing-sensitive communications.
10.1 Clock Frequency and Clock
Switching
PIC24HJXXXGPX06/X08/X10 devices allow a wide
range of clock frequencies to be selected under appli-
cation control. If the system clock configuration is not
locked, users can choose low-power or high-precision
oscillators by simply changing the NOSC bits (OSC-
CON<10:8>). The process of changing a system clock
during operation, as well as limitations to the process,
are discussed in more detail in Section 9.0 “Oscillator
Configuration”.
10.2 Instruction-Based Power-Saving
Modes
PIC24HJXXXGPX06/X08/X10 devices have two spe-
cial power-saving modes that are entered through the
execution of a special PWRSAV instruction. Sleep mode
stops clock operation and halts all code execution. Idle
mode halts the CPU and code execution, but allows
peripheral modules to continue operation. The assem-
bly syntax of the PWRSAV instruction is shown in
Example 10-1.
Note:
SLEEP_MODE and IDLE_MODE are
constants defined in the assembler
include file for the selected device.
Sleep and Idle modes can be exited as a result of an
enabled interrupt, WDT time-out or a device Reset. When
the device exits these modes, it is said to “wake-up”.
10.2.1 SLEEP MODE
Sleep mode has these features:
• The system clock source is shut down. If an
on-chip oscillator is used, it is turned off.
• The device current consumption is reduced to a
minimum, provided that no I/O pin is sourcing
current.
• The Fail-Safe Clock Monitor does not operate
during Sleep mode since the system clock source
is disabled.
• The LPRC clock continues to run in Sleep mode if
the WDT is enabled.
• The WDT, if enabled, is automatically cleared
prior to entering Sleep mode.
• Some device features or peripherals may continue
to operate in Sleep mode. This includes items such
as the input change notification on the I/O ports, or
peripherals that use an external clock input. Any
peripheral that requires the system clock source for
its operation is disabled in Sleep mode.
The device will wake-up from Sleep mode on any of
these events:
• Any interrupt source that is individually enabled.
• Any form of device Reset.
• A WDT time-out.
On wake-up from Sleep, the processor restarts with the
same clock source that was active when Sleep mode
was entered.
EXAMPLE 10-1: PWRSAV INSTRUCTION SYNTAX
PWRSAV #SLEEP_MODE
PWRSAV #IDLE_MODE
; Put the device into SLEEP mode
; Put the device into IDLE mode
© 2009 Microchip Technology Inc.
DS70175H-page 131