82443BX Datasheet, PDF (120/132 Pages) Intel Corporation – Host Bridge/Controller

Functional Description
Figure 4-8. External Glue Logic Drives CPU Clock Ratio Straps
12
HCLK
SUS_DIS strap
PCIRST#
PCLK
p_creset#
CRESET#
CPU straps
Suspend disable value latched when PCIRST#↑
0 01 2
....
1 ms
CPU strap values from external Glue Logic
33,333
4.8.2.3
82443BX Straps
The 82443BX strapping options are latched in the rising edge of PCIRST#.
4.8.3 Suspend Resume
4.8.3.1 Suspend Resume protocols
The suspend resume sequences are indicated to the 82443BX by the PIIX4E, using SUS_STAT#,
and PCIRST#. In addition, the 82443BX contains NREF_EN and CRst_En configuration bits that
participate in the suspend resume sequences. As a result of suspend resume, the 82443BX performs
the following activities: Changing its refresh mode, performing internal and CPU reset and Isolate
or re-enable normal IO buffers.
Table 4-17. Suspend / Resume Events and Activities
State
ON
POSCL/STR
POS
POSCCL
SUSTAT# PCIRST# CrstEn
RESET
assert inactive
deassert active
--
-
reset exclude
resume/ref logic
deassert inactive
0 no resets
deassert inactive
1 reset CPU only
REFRESH
IO
BUFFERS
switch to suspend refresh
suspend refresh
NREF_EN remains
inactive
auto switch to normal ref
NREF_EN is set
auto switch to normal ref
NREF_EN is set
isolate
enable
enable
enable
4.8.3.2
Suspend Refresh
Suspend Refresh Modes
The 82443BX supports suspend refresh by providing a mechanism to transition in and out of
suspend. The supported suspend refresh types are:
• Self Refresh when SDRAM are used
• Self Refresh when EDO -DRAMs are used
• CBR Refresh when EDO-DRAMs are used
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82443BX Host Bridge Datasheet