AMD SC2200 manual Power Planes of External Interface Signals, DC Current

Electrical Specifications 32580B

Table 9-4indicates which power rails are used for each signal of the SC2200 external interface. Power planes not listed in this table are internal, and are not related to signals of the external interface.

Table 9-4. Power Planes of External Interface Signals

Power Plane	Signal Names	VCC Balls	VSS Balls
Standby	GPWIO[0:2], LED#, ONCTL#, PWRBTN#, PWRCNT[1:2],	VSB	VSS
	THRM#, CLK32, IRRX1, RI2#, SDATA_IN2
Battery	X32I, X32O	VBAT	VSS
CRT DAC	RED, GREEN, BLUE, VREF, SETRES	AVCCCRT	AVSSCRT
USB	DPOS_PORT1, DNEG_PORT1, DPOS_PORT2,	AVCCUSB	AVSSUSB
	DNEG_PORT2, DPOS_PORT3, DNEG_PORT3
I/O	All other external interface signals	VIO	VSS

9.1.5DC Current

DC current is not a simple measurement. Three of the SC2200 power states (On, Active Idle, Sleep) were selected for measurement. For each power state mea- sured, two functional characteristics (Typical Average, Absolute Maximum) are used to determine how much cur- rent the SC2200 uses.

9.1.5.1Power State Parameter Definitions

The DC characteristics tables in this section list Core and I/ O current for three of the power states. For more explana- tion on the SC2200 power states see Section 6.2.9 "Power Management Logic" on page 166.

•On (C0): All internal and external clocks with respect to the SC2200 are running and all functional blocks inside the GX1 module (CPU Core, Memory Controller, Display Controller, etc.) are actively generating cycles. This is equivalent to the ACPI specification’s “S0,C0” state.

•Active Idle (C1): 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. 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 (SL2): This is the lowest power state the SC2200 can be in with voltage still applied to the device’s core and I/O supply pins. This is equivalent to the ACPI spec- ification’s “S1” state.

9.1.5.2Definition and Measurement Techniques of SC2200 Current Parameters

These parameters describe the current while the SC2200 is in the On state:

•Typical Average: Indicates the average current used by the SC2200 while in the On state. This is measured by running typical Windows applications in a typical display state. 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 SC2200 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. Typical power is based on a combination of On (Typical Average) and Active Idle states.

•Absolute Maximum: Indicates the maximum instanta- neous current used by the SC2200. CPU Core current is measured by running the Landmark Speed 200 bench- mark 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 each of the display type supported (CRT and TFT).

AMD Geode™ SC2200 Processor Data Book 371