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Electrical Specifications
Table 9-44. Power-Up Sequence Not Using the Power Button Timing Parameters
Symbol
Parameter
t
Voltage sequence
1
t
POR# inactive after V
2
and V
applied
IO
t
32KHZ startup time
3
1
V
V
SBL,
CORE
2
V
V
SB,
IO
POR#
32KHZ
1)
V
and V
should be tied together.
SBL
CORE
2)
V
and V
should be tied together.
SB
IO
Figure 9-56. Power-Up Sequencing Without PWRBTN# Timing Diagram
ACPI is non-functional and all ACPI outputs are undefined when the power-up sequence does not include using the power
button. SUSP# is an internal signal generated from the ACPI block. Without an ACPI reset, SUSP# can be permanently
asserted. If the USE_SUSP bit in CCR2 of GX1 module is enabled (Index C2h[7] = 1), the CPU will stop.
If ACPI functionality is desired, or the situation described above avoided, the power button must be toggled. This can be
done externally or internally. GPIO63 is internally connected to PWRBTN#. To toggle the power button with software,
GPIO63 must be programmed as an output using the normal GPIO programming protocol (see Section 6.4.1.1 "GPIO Sup-
port Registers" on page 222). GPIO63 must be pulsed low for at least 16 ms and not more than 4 sec.
Asserting POR# has no effect on ACPI. If POR# is asserted and ACPI was active prior to POR#, then ACPI will remain
active after POR#. Therefore, BIOS must ensure that ACPI is inactive before GPIO63 is pulsed low.
AMD Geode™ SC3200 Processor Data Book
Min
-100
, V
, V
,
SBL
CORE
SB
t
1
t
2
Max
Unit
100
ms
50
ms
1
s
t
3
32581C
Comments
Optimum power-up results with
t
= 0.
1
POR# must not glitch during
active time.
Time required for 32 KHz oscilla-
tor and 14.318 MHz derived from
PLL6 to become stable at which
time the RTC can reliably count.
Spec assumes unbalanced exter-
nal circuit, see Section 5.5.2.1 on
page 103 for more details.
417
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