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AMD Geode™ LX Processors Data Book 599
Electrical Specifications
33234H
7.4 DC Current
DC current is not a simple measurement. Three of the
AMD Geode LX processor’s power states (ON, Active Idle,
and Sleep) were selected for measurement. For the ON
power state measured, two functional characteristics (Typi-
cal Average and Absolute Maximum) are used to deter-
mine how much current the processor requires.
7.4.1 Power State Parameter Definitions
The DC current tables in this section list Core and I/O cur-
rent for three of the power states.
•On (S0/C0): All internal and external clocks with respect
to the AMD Geode LX processor are running and all
functional blocks (CPU Core, Memory Controller,
Display Controller, etc.) are actively generating cycles.
This is equivalent to the ACPI specification’s “S0/C0”
state.
• Active Idle (S0/C1): The CPU Core has been halted
and all other functional blocks (including the Display
Controller for refreshing the display) are actively gener-
ating cycles. This state is entered when a HLT instruc-
tion is executed by the CPU Core. From a user’s
perspective, this state is indistinguishable from the On
state and is equivalent to the ACPI specification’s
“S0/C1” state.
• Sleep (S1): This is the lowest power state the
AMD Geode LX processor can be in with voltage still
applied to the device’s core and I/O supply pins. This is
equivalent to the ACPI specification’s “S1” state.
All measurements were taken at 25°C ambient air.
7.4.2 Definition and Measurement Techniques
of Current Parameters
The following two parameters describe the AMD Geode LX
processor current while in the ON state:
Typical Average
Typical Average (Typ Avg) indicates the average current
used by the AMD Geode LX processor while in the ON
state, with no active power management. This measure-
ment is comprised of two components: WinBench
®
99
Business Graphics Test and Active Idle power measure-
ments. WinBench 99 represents a maximum typical state
as it simulates a knowledgeable worker’s typical day com-
pressed into the shortest period of time possible. Since it is
not possible for someone to operate as fast as the bench-
mark, the resulting power from the benchmark is averaged
with Active Idle in an 80/20 ratio, with 80% of the time being
in the Windows
®
XP Idle state and 20% of the time running
applications. This results in a Typical Average power result.
For each voltage, power is measured at one second inter-
vals. The measurements are then averaged together to
produce the final number. The CRT resolution is
1024x768x32 bpp, at 85 Hz refresh and the TFT resolution
is 1024x768 x16 bpp at 60 Hz refresh. This number is pro-
vided for reference only since it can vary depending on the
usage model of the system.
Thermal Design Power
Absolute Maximum and Thermal Design Power (TDP) indi-
cates the maximum average current used by the
AMD Geode LX processor. This is measured with the volt-
ages at maximum. An internally-developed AMD applica-
tion called Pathological Power Measurement Application
causes the AMD Geode LX processor to consume the
maximum amount of power for the Core and I/O rails, while
WinBench 99 Business Graphics Test causes the
AMD Geode LX processor to consume maximum power on
the memory rail. All tests were run at the maximum sup-
ported resolution of 1920x1440x32 bpp at 72 Hz refresh for
the CRT and 1600x1200x16 bpp at 60 Hz refresh for TFT.
This test does not guarantee maximum current. There may
be pathological applications that result in higher measured
currents.
TDP is a function of all power contributors at maximum.
Applications that do not use the CRT or TFT output will
have a somewhat lower TDP. Operating the memory sub-
system at a lower frequency will also lower TDP. Specific
software applications may place lower compute demands
on the CPU, which lowers the TDP as well.
If needed, it is up to the system designer to determine TDP
for systems that operate with conditions that are different
then those specified, however, the TDP specified is the
maximum.
Active Idle
Active Idle power is measured at the Windows XP Idle
state when the monitor is still turned on. During this state
the “Bliss” background is used. The CRT resolution is
1024x768x32 bpp, at 85 Hz refresh and 1024x768 x16 bpp
at 60 Hz refresh is used for TFT. This number is provided
for reference only since it can vary depending on the back-
ground image and processes running on the system.
Sleep
The Sleep power state is achieved by forcing the system
into a “S1” state as defined by the ACPI specification.
7.4.3 DC Current Measurements
Tables 7-3, 7-4, and 7-5 show the DC current measure-
ments of the AMD Geode LX processor family. The proces-
sor supports CRT or TFT displays.
The CRT DACs require current; while the TFT interface,
even though it has no DAC to power, also draws current
while it is active. Therefore, the CRT DACs and the TFT
interface currents are specified in separate tables.