cs5535 National Semiconductor Corporation, cs5535 Datasheet - Page 46

• Manufacturer Part Number: cs5535
• Description: Geode Cs5535 Companion Multi-function South Bridge
• Manufacturer: National Semiconductor Corporation

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Signal Definitions
Function Name
PWR_BUT#
AC_S_IN2
SLP_CLK_EN#
SLEEP_BUT
Table 2-9. GPIOx Available Functions Descriptions (Continued)
Ball
No.
(Continued)
A8
A1
F2
J3
GPIO[x]
GPIO28
GPIO12
GPIO11
GPIO13
Type
O
I
I
I
Description
Power Button. This GPIO can be mapped to the PMC “button-
push” event, that may be used to implement the power ON and the
four-second-delay power OFF functions. Note that GPIO28 comes
up in the AUX_IN mode after reset, enabling this feature.
Any power button change on this input must be at least two
KHZ32_XCI edges (approximately 62 µs) in duration to be cor-
rectly detected. If spurious transitions smaller than this are possi-
ble, then use on-chip GPIO input filter function to insure proper
operation. Additionally, the rise or fall time on this input must be
less than 10 µs. If transition times longer than this are possible,
then use the on-chip GPIO input filter function to insure proper
operation.
From the first power-up of the Standby power domain under which
no filter is enabled, spurious transitions on the first high-to-low
power button push are acceptable as long as the input is eventu-
ally low at least two KHZ32_XCI edges. Additionally, transition
times as slow as one milli-second are acceptable for the first push.
Note that these relaxed requirements work because this input is
effectively a “don’t care” at the hardware level after the first power-
up until software enables use of the power button. Before enabling
use, the software can setup the GPIO filter or other functions as
needed.
Per the discussion of the “skip” feature in Section 4.17 "Power
Management Control" on page 159, this input may be tied to
ground in order for the system to come on immediately when
Standby and Working power are available. Specifically, systems
that do not incorporate a power button should tie this input to
ground.
One side effect of the “skip” feature, is that the platform design
must insure that this input is not low when Standby power is
applied if the “skip” feature is not desired. Specifically, systems
that do incorporate use of a power button must insure that this
input ramps to a “high” no more than 1 µs behind V
up. Failure to quickly establish a “high” on this input during power-
up could result in a spurious “skip”.
Audio Controller Serial Data Input 2. This input receives serial
data from a second codec. This data stream contains both control
data and ADC audio data. This input data is sampled on the falling
edge of AC_CLK. If the codec’s Ready bit is set in this stream (slot
0, bit 15), then it is functionally OR-ed with AC_SDATA_IN1. Con-
nect to second codec’s serial data output.
Sleep Clock Enable. This signal is a control that is intended to be
connected to the external system clock generator chip. The
intended use is, when high, the clock generator runs; when low,
the clock generator turns off. From reset, a pull-up makes this
GPIO high. The active state of this signal indicates that the
CS5535 is in the Sleep state.
Sleep Button. This GPIO can be mapped to a PME “button-push”
type event, that may be used to request the system software to put
the system to Sleep.
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IO_VSB
ramp-
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