FDC37B78X SMSC Corporation, FDC37B78X Datasheet - Page 148

• Manufacturer Part Number: FDC37B78X
• Description: Enhanced Super I/O Controller with ACPI Support/ Real Time Clock and Consumer IR
• Manufacturer: SMSC Corporation

This chip employs soft power management to
allow the chip to enter low power mode and to
provide a variety of wakeup events to power up
the chip.
control over powerdown and wakeup events. In
low power mode, the chip runs off of the trickle
voltage, VTR. In this mode, the chip is ready to
power up from either the power button or from
one of a number of wakeup events including
pressing a key, touching the mouse or receiving
data from one of the UARTs.
also be set to power up the system at a
predetermined time to perform one or more
tasks.
The implementation of Soft Power Management
is illustrated in Figure 11.
transition on the Button input or on any of the
enabled wakeup events (SPx) causes the
nPowerOn output to go active low which turns
on the main power supply. Even if the power
supply is completely lost (i.e., VTR is not
present) the power supply can still be turned on
upon the return of VTR. This is accomplised by
an alarm event that has already passed (if the
alarm remember bit is enabled) or by a VTR
power on reset (if the VTR POR bit is enabled).
These bits are described in the RTC section.
This technique allows for software
A high to low
SOFT POWER MANAGEMENT
The alarm can
148
The chip can also be programmed to always
stay off when the AC power returns. (See
VTR_POR_OFF in the RTC section.)
The Button input can be used to turn off the
power supply after a debounce delay.
power supply can also be turned off under
software control (via a write to register
WDT_CTRL with bit 7 set).
Configuration registers L8-CR_B0 and L8-
CR_B1 select the wakes-up events (SPx). The
Configuration registers L8-CR_B2 and L8-
CR_B3 indict the wake-up event status.
possible wake-events are:
UART1 and UART 2 Ring Indicator Pin
Keyboard and Mouse clock Pin
Group Interrupt 1, Group Interrupt 2
IRRX2 input pin
RTC Alarm
UART 1 and UART 2 Receive Data Pin
nRING pin
Consumer IR (CIR)
Power Button input pin
VTR_POR
The
The