SMM764 SUMMIT Microelectronics, Inc:, SMM764 Datasheet - Page 18

• Manufacturer Part Number: SMM764
• Description: Four-channel Active Dc Output Controller, Monitor, Marginer And Sequencer With Sequence-link
• Manufacturer: SUMMIT Microelectronics, Inc:

LINKED OPERATION
The SMM764 can be linked to multiple Sequence-
Link devices to create a seamless multi-channel
power manager. With linked operation 8 Sequence-
Link devices in a system can sequence up to 46
supplies
sequencing in this mode can be interlaced, sequencing
a supply from device A, then from device B, then again
from device A, etc. This extended sequencing is made
possible by the inclusion of a SEQ_LINK pin.
For this mode of operation, the control pins, including
SEQ_LINK, PWR_ON, and FS# on each device must
be tied together. In addition, the VDD and 12V supply
must also be connected on all linked devices. As a
consequence when multiple devices are linked
together, all devices must be powered by the same
supply.
RESTART
There are two possible conditions in which a restart
sequence may be initiated. The first instance occurs
when either the FS# pin is asserted or the PWR_ON
pin is pulled low thus initiating a command-triggered
restart. The second condition occurs when a user
programmable
operation or a power-off sequence thus resulting in a
fault-triggered restart.
In either case, the SMM764 will wait until all voltages
have fallen below their user programmable OFF
thresholds, after all channels are off, the PWR_ON pin
will continue to be held low for a period of time
dependent on the nature of the fault.
When a power-off or force-shutdown condition results
from
shutdown, the SMM764 will automatically begin the
restart procedure. When restart begins an internal
timer will begin to timeout for a command-triggered
Restart Delay (t
expired the PWR_ON pin is released, allowing the
power-on sequence to begin.
When a power-off or force-shutdown condition results
from a fault-triggered power-off or force-shutdown, the
SMM764 may or may not begin the restart procedure
(see PROGRAMMABLE RETRIES), if restart begins
the internal timer will begin to timeout a fault-triggered
Restart Delay (t
is released allowing the power-on Sequence to begin.
Summit Microelectronics, Inc
APPLICATIONS INFORMATION (CONTINUED)
a
within
command-triggered
FTRD
CTRD
fault
29
) of 2.4 s before the PWR_ON pin
) of 12.5 ms. After this time has
sequence
triggers
power-off
a
positions.
force-shutdown
or
force-
The
2098 1.1 6/29/2005
If the SMM764 is programmed to wait for VDD, 12VIN,
or Internal Temp to be valid (above UV1 and below
OV1) before power-on sequencing may commence,
then this condition will be checked after the restart
timer has expired and the PWR_ON pin has been
released.
The conditions that may lead to a Fault-Triggered
restart include any channel exceeding its user
programmable thresholds (OV or UV), set to trigger
either a force-shutdown or a power-off sequence. In
addition, in the event that the sequence termination
timer times out before a channel reaches its UV1 or
OFF threshold, during sequencing, a Fault-Triggered
restart occur.
I
Power-on sequencing is only permitted while the
PWR_ON pin is active. Once the PWR_ON pin is
active and the SMM764 has entered monitoring mode,
an I
power-off sequence. This condition will continue until
an I
PROGRAMMABLE RETRIES
In the event of a persistent system fault, the SMM764
may be programmed to limit the number of Fault-
Triggered restarts it will allow. This programmable
setting ensures that the SMM764 will not enter a
hiccup-mode
susceptibility to transient fault conditions.
In the event of a Fault-Triggered restart the fault will
be registered and internally compared to the maximum
number of allowable faults. If this number is exceeded
then the fault condition will be latched and the
PWR_ON and FS# pins will be pulled low while the
RST# output is asserted. This fault condition will
remain latched until power is cycled on the SMM764,
at which point the PWR_ON and FS# pins will be
released, the number of faults will be reset zero, and
the restart sequence will begin. The allowable
programmable
unlimited retries.
2
C POWER OFF CONTROL
2
2
C “power on” command is issued.
C command may be issued to commence the
of
setting
operation,
include
Preliminary Information
while
one,
SMM764
still
three,
reducing
and
18