32579BElectrical Specifications

Table 9-47. Power-Up Sequence Not Using the Power Button Timing Parameters

Symbol

Parameter

Min

Max

Unit

Comments

 

 

 

 

 

 

t1

Voltage sequence

-100

100

ms

Optimum power-up results with

 

 

 

 

 

t1 = 0.

t2

POR# inactive after VSBL, VCORE, VSB,

50

 

ms

POR# must not glitch during

 

and VIO applied

 

 

 

active time.

t3

32KHZ startup time

 

1

s

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.

 

 

 

 

 

Assumes unbalanced external

 

 

 

 

 

circuit. See Table 5.5.2.1 "Inter-

 

 

 

 

 

nal Oscillator" on page 105 for

 

 

 

 

 

details.

 

 

 

 

 

 

VSBL, VCORE

1

t1

 

VSB, VIO2

t2

POR#

t3

32KHZ

1)VSBL and VCORE should be tied together.

2)VSB and VIO should be tied together.

Figure 9-57. 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 224). 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.

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AMD Geode™ SC1200/SC1201 Processor Data Book

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AMD SC1200, SC1201 manual POR# 32KHZ, 434