SC2200 datasheet(425/433 Pages) NSC

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Electrical Specifications (Continued)

Figure 8-56. Power-Up Sequencing Without PWRBTN# Timing Diagram

ACPI is non-functional when the power-up sequence does not include using the power button. If ACPI functionality is

desired, 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 5.4.1.1 "GPIO Support Registers" on page 231). GPIO63 must be pulsed low for at

least 16 msec 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.

Table 8-44. Power-Up Sequence Not Using the Power Button Timing Parameters

Symbol

Parameter

Min

Max

Unit

Comments

Voltage sequence

-10

POR# inactive after VSBL,VCORE,VSB,

and VIO applied

POR# must not glitch during

active time.

32KHZ startup 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.

VSBL, VCORE

VSB, VIO

POR#

VSBL and VCORE should be tied together.

VSB and VIO should be tied together.

32KHZ

SC2200 Datasheet(PDF) 425 Page - National Semiconductor (TI)