LPC47M182 SMSC Corporation, LPC47M182 Datasheet - Page 150

• Manufacturer Part Number: LPC47M182
• Description: ADVANCED I/O CONTROLLER WITH MOTHERBOARD GLUE LOGIC
• Manufacturer: SMSC Corporation

Revision 1.8 SMSC/Non-SMSC Register Sets (02-24-05)
Tr
Tf
Tpropf
Tpropr
CO
CL
t3
t4
NAME
LATCHED_BF_CUT
nBACKFEED_CUT
PWRGD_PS
The second possible sequence, shown in the figure below, is a normal powerdown sequence. The
nBACKFEED_CUT signal goes from low to high when nSLP_S3 goes low, and nSLP_S5 goes from high
to low 30usec to 65usec (t3) later.
The
LATCHED_BF_CUT returns to low when nSLP_S5 goes low.
The nBACKFEED_CUT stays high and nSLP_S5 stays low for an indeterminate time and then nSLP_S5
will go high. A minimum of 1msec (t4) later, nBACKFEED_CUT will go low and the system returns to the
end of the power-up sequence when nSLP_S3 and PWRGD_PLATFORM goes high. Typical measured
values of t4 are approximately 250msec. During all transitions, the propagation delays, rise and fall times
and power regulation times for LATCHED_BF_CUT are as described in Figure 7.17. The first sequence
can start at the end of this power-up sequence at any time.
The following figure shows a flowchart of the logic.
nSLP_S3
nSLP_S5
LATCHED_BF_CUT rise time. Measured
from 10% to 90%.
LATCHED_BF_CUT fall time. Measured from
90% to 10%.
LATCHED_BF_CUT high to low propagation
delay. Measured from
nBACKFEED_CUT/nSLP_S5 threshold to
90% of LATCHED_BF_CUT
LATCHED_BF_CUT low to high propagation
delay. Measured from
nBACKFEED_CUT/nSLP_S5 threshold to
10% of LATCHED_BF_CUT
Output Capacitance
Load Capacitance
nBACKFEED_CUT inactive to nSLP_S5
active
nSLP_S5 inactive to nBACKFEED_CUT
active
LATCHED_BF_CUT
Table 7.46 – Latched Backfeed Cut Sequence 1 and 2 Timing
Tpropr
Tr
DESCRIPTION
Figure 7.17 – Latched Backfeed Cut Sequence 2
t3
signal
DATASHEET
Tpropf
Tf
goes
high
150
when
30
1
MIN
nBACKFEED_CUT
Advanced I/O Controller with Motherboard GLUE Logic
250
TYP
1
1
50
50
25
50
60
MAX
goes
t4
high
us
us
ns
ns
pF
pF
us
ms
UNITS
SMSC LPC47M182
and
Datasheet
then