DSPIC33FJ32GS608 datasheet(199/416 Pages) MICROCHIP

199 / 416 page

 2009 Microchip Technology Inc.

Preliminary

DS70591B-page 199

dsPIC33FJ32GS406/606/608/610 and dsPIC33FJ64GS406/606/608/610

10.0 POWER-SAVING FEATURES

The

dsPIC33FJ32GS406/606/608/610

and

dsPIC33FJ64GS406/606/608/610 devices provide the

ability to manage power consumption by selectively man-

aging 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 consumed power.

dsPIC33FJ32GS406/606/608/610

and

dsPIC33FJ64GS406/606/608/610 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

selectively tailor an application’s power consumption

while still maintaining critical application features, such

as timing-sensitive communications.

10.1

Clock Frequency and Clock

Switching

The

dsPIC33FJ32GS406/606/608/610

and

dsPIC33FJ64GS406/606/608/610 devices allow a

wide range of clock frequencies to be selected under

application control. If the system clock configuration is

not locked, users can choose low-power or high-

precision oscillators by simply changing the NOSC bits

(OSCCON<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

The

dsPIC33FJ32GS406/606/608/610

and

dsPIC33FJ64GS406/606/608/610 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-

bler syntax of the PWRSAV instruction is shown in

Example 10-1.

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

The following occur in Sleep mode:

• 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,

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. This includes the 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.

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 mode, the processor restarts

with the same clock source that was active when Sleep

mode was entered.

EXAMPLE 10-1:

PWRSAV INSTRUCTION SYNTAX

Note 1: This data sheet summarizes the features

of the dsPIC33FJ32GS406/606/608/610

and

dsPIC33FJ64GS406/606/608/610

families of devices. It is not intended to be

a comprehensive reference source. To

complement the information in this data

sheet, refer to Section 9. “Watchdog

Timer

and

Power-Saving

Modes”

(DS70196) in the “dsPIC33F/PIC24H

Family Reference Manual”, which is avail-

able from the Microchip web site

(www.microchip.com).

2: Some registers and associated bits

described in this section may not be avail-

able on all devices. Refer to Section 4.0

“Memory Organization” in this data

sheet for device-specific register and bit

information.

Note:

SLEEP_MODE

and

IDLE_MODE

are

constants defined in the assembler

include file for the selected device.

PWRSAV #SLEEP_MODE

; Put the device into SLEEP mode

PWRSAV #IDLE_MODE

; Put the device into IDLE mode

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