GX1 datasheet(191/247 Pages) NSC

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Electrical Specifications (Continued)

6.5

DC CHARACTERISTICS

6.5.1

Input/Output DC Characteristics

Table 6-5 shows the input/output DC parameters for all the devices in the GX1 processor series.

6.5.2

DC Current

DC current is not a simple measurement. The CPU has

four power states and two functional characteristics that

determine how much current the processor uses at any

given point in time.

6.5.2.1

Definition of CPU Power States

The following DC characteristic tables list CPU core and

I/O current for four distinct CPU power states:

•On: All internal and external clocks with respect to the

processor are running and all functional blocks inside

the processor (CPU core, memory controller, display

controller, etc.) are actively generating cycles. This is

equivalent to the ACPI specification’s “S0” state.

•Active Idle: The CPU core has been halted, all other

functional blocks (including the display controller for

refreshing the display) are actively generating cycles.

This state is entered when a HLT instruction is executed

by the CPU core or the SUSP# pin is asserted. From a

user’s perspective, this state is indistinquishable from

the “On” state and is equivalent to the ACPI specifica-

tion’s “S1” state.

• Standby: The CPU core has been halted and all internal

clocks have been shut down. Externally, the SYSCLK

input continues to be driven. This is equivalent to the

ACPI specification’s “S2” or “S3” state.

•Sleep: Very similar to “Standby” except that the

SYSCLK input has been shut down as well. This is the

lowest power state theprocessor canbeinwithvoltage

still applied to the device’s core and I/O supply pins. This

is equivalent to the ACPI specification’s “S4BIOS” state.

6.5.2.2

Definition and Measurement Techniques of

CPU Current Parameters

The following two parameters indicate processor current

whileinthe “On” state:

• Typical Average: Indicates the average current used by

theprocessor whileinthe “On” state. This is measured

by running typical Windows applications in a typical

display mode. In this case, 800x600x8 bpp at 75 Hz, 50

MHz DCLK using a background image of vertical stripes

(4-pixel wide) alternating between black and white with

power management disabled (to guarantee that the

processor never goes into the Active Idle state). This

number is provided for reference only since it can vary

greatly depending on the usage model of the system.

Note:

This typical average should not be confused with

the typical power numbers shown in Table 6-1 on

page 185. The numbers in Table 6-1 are based on

a combination of “On (Typical Average)” and

“Active Idle” states.

• Absolute Maximum: Indicates the maximum instanta-

neous current used by the processor. CPU core current

is measured by running the Landmark Speed 200™

benchmark test (with power management disabled) and

measuring the peak current at any given instant during

the test. I/O current is measured by running Microsoft

Windows 98 and using a background image of vertical

stripes (1-pixel wide) alternating between black and

white at the maximum display resolution of

1280x1024x8 bpp at 75 Hz, 135 MHz DCLK.

Table 6-5. DC Characteristics (at Recommended Operating Conditions)

Symbol

Parameter

Min

Typ

Max

Units

Comments

VOL

Output Low Voltage

0.4

IOL =5 mA

VOH

Output High Voltage

2.4

IOH = –2mA

Input Leakage Current for all input pins

except those with internal pull up/pull downs

(PU/PDs).

±10

µA0 < V

IN <VCC3,

See Table 6-2

IIH

Input Leakage Current for all pins with

internal PDs.

200

µAV

IH =2.4 V,

See Table 6-2

IIL

Input Leakage Current for all pins with

internal PUs.

–400

µAV

IL =0.35 V,

See Table 6-2

CIN

Input Capacitance

f=1 MHz1

Not 100% tested.

COUT

Output or I/O Capacitance

f=1 MHz1

CCLK

CLK Capacitance

f=1 MHz1

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