Legacy-Free Keyboard/Embedded Controller with SPI and LPC Docking Interface
8051 in sleep mode.
RTC, 8051 and other VCC1
driven pins are active
Wake Up Events
RTC Alarm,
Power Button,
Ring Indicator,
etc.
N
Unmasked
Wake-up
Event ?
Y
INT5_N generated.
Turn on ring oscillator.
SLEEPFLAG = 0.
Once stabilized, the ring
oscillator is gated through to
the 8051.
The 8051 is now running in
Idle mode and responds
immediately to T5INT.
8051 leaves Idle mode,
executes int5_n service
routine (disables int5_n) and
executes an IRET when
done.
8051 returns to executing
from where it left off prior to
entering sleep mode.
Figure 12.4 Exiting Sleep Mode
12.3
Wake-Up Events
There are two types of wake-up events that can occur, internal (Table 12.1, "Internal System Wake-Up
Events") and external (Table 12.2, "External System Wake-Up Events"). Wake-up events on General
Purpose Pins can be either edge or selectable edges. Refer to Table 12.1 for further description. Wake-
up events can occur when VCC2 is off. VCC1 must be on for a wake-up event to occur, but the high-
performance 8051 can be in sleep mode.
Table 12.1 Internal System Wake-Up Events
WAKE-UP EVENTS
REGISTER
DESCRIPTION
RTC_ALRM
HTIMER
Wake Up Src 1 (0x7F2B) [D0]
Wake Up Src 2 (0x7F2B) [D2]
Wake Up Src 1 (0x7F2A) [D5]
RTC alarm
Hibernation timer
PM1 Status
PM1_STS2
Revision 1.1 (01-14-03)
140
SMSC LPC47N350
DATASHEET
SMSC [ SMSC CORPORATION ]
