PIC18F44J50-I Datasheet, PDF (54/562 Pages) Microchip Technology – 28/44-Pin, Low-Power, High-Performance USB Microcontrollers

PIC18F46J50 FAMILY
4.5.4
EXIT WITHOUT AN OSCILLATOR
START-UP DELAY
Certain exits from power-managed modes do not
invoke the OST at all. There are two cases:
• PRI_IDLE mode (where the primary clock source
is not stopped) and the primary clock source is
the EC mode
• PRI_IDLE mode and the primary clock source is
the ECPLL mode
In these instances, the primary clock source either
does not require an oscillator start-up delay, since it is
already running (PRI_IDLE), or normally does not
require an oscillator start-up delay (EC).
4.6 Deep Sleep Mode
Deep Sleep mode brings the device into its lowest
power consumption state without requiring the use of
external switches to remove power from the device.
During Deep Sleep, the on-chip VDDCORE voltage reg-
ulator is powered down, effectively disconnecting
power to the core logic of the microcontroller.
Note:
Since Deep Sleep mode powers down the
microcontroller by turning off the on-chip
VDDCORE voltage regulator, Deep Sleep
capability is available only on PIC18FXXJ
members in the device family. The on-chip
voltage regulator is not available on
PIC18LFXXJ members of the device
family, and therefore, they do not support
Deep Sleep.
On devices that support it, the Deep Sleep mode is
entered by:
• Setting the REGSLP (WDTCON<7>) bit
• Clearing the IDLEN bit
• Clearing the GIE bit
• Setting the DSEN bit (DSCONH<7>)
• Executing the SLEEP instruction immediately after
setting DSEN (no delay or interrupts in between)
In order to minimize the possibility of inadvertently enter-
ing Deep Sleep, the DSEN bit is cleared in hardware,
two instruction cycles after having been set. Therefore,
in order to enter Deep Sleep, the SLEEP instruction must
be executed in the immediate instruction cycle after set-
ting DSEN. If DSEN is not set when Sleep is executed,
the device will enter conventional Sleep mode instead.
During Deep Sleep, the core logic circuitry of the
microcontroller is powered down to reduce leakage
current. Therefore, most peripherals and functions of
the microcontroller become unavailable during Deep
Sleep. However, a few specific peripherals and func-
tions are powered directly from the VDD supply rail of
the microcontroller, and therefore, can continue to
function in Deep Sleep.
Entering Deep Sleep mode clears the DSWAKEL
register. However, if the Real-Time Clock and Calendar
(RTCC) is enabled prior to entering Deep Sleep, it will
continue to operate uninterrupted.
The device has a dedicated Brown-out Reset (DSBOR)
and Watchdog Timer Reset (DSWDT) for monitoring
voltage and time-out events in Deep Sleep. The
DSBOR and DSWDT are independent of the standard
BOR and WDT used with other power-managed modes
(Run, Idle and Sleep).
When a wake event occurs in Deep Sleep mode (by
MCLR Reset, RTCC alarm, INT0 interrupt, ULPWU or
DSWDT), the device will exit Deep Sleep mode and
perform a Power-on Reset (POR). When the device is
released from Reset, code execution will resume at the
device’s Reset vector.
4.6.1 PREPARING FOR DEEP SLEEP
Because VDDCORE could fall below the SRAM retention
voltage while in Deep Sleep mode, SRAM data could
be lost in Deep Sleep. Exiting Deep Sleep mode
causes a POR; as a result, most Special Function
Registers (SFRs) will reset to their default POR values.
Applications needing to save a small amount of data
throughout a Deep Sleep cycle can save the data to the
general purpose DSGPR0 and DSGPR1 registers. The
contents of these registers are preserved while the
device is in Deep Sleep, and will remain valid throughout
an entire Deep Sleep entry and wake-up sequence.
DS39931D-page 54
 2011 Microchip Technology Inc.