8

FN9062.2

April 13, 2004

well as all the control and monitoring functions necessary for

complete ACPI implementation.

Initialization

The ISL6504/A automatically initializes upon receipt of input

power. The Power-On Reset (POR) function continually

after exceeding POR threshold.

Dual Outputs Operational Truth Table

Table 1 describes the truth combinations pertaining to the

highlight the only difference between the ISL6504 and

ISL6504A. The internal circuitry does not allow the transition

from an S3 (suspend to RAM) state to an S4/S5 (suspend to

disk/soft off) state or vice versa. The only ‘legal’ transitions

are from an active state (S0, S1) to a sleep state (S3, S5)

and vice versa.

Functional Timing Diagrams

Figures 4 (ISL6504), 5 (ISL6504A), and 6 are timing diagrams,

detailing the power up/down sequences of all the outputs in

response to the status of the sleep-state pins (S3, S5), as well

as the status of the input ATX supply. Not shown in these

diagrams is the deglitching feature used to protect against false

sleep state tripping. Both S3 and S5 pins are protected against

noise by a 2

µs filter (typically 1–4µs). This feature is useful in

noisy computer environments if the control signals have to

travel over significant distances. Additionally, the S3 pin

features a 200

µs delay in transitioning to sleep states. Once the

S3 pin goes low, an internal timer is activated. At the end of

the 200

µs interval, if the S5 pin is low, the ISL6504/A

switches into S5 sleep state; if the S5 pin is high, the

ISL6504/A goes into S3 sleep state.

S5

S3

3.3VDL/SB

5VDL

COMMENTS

1

1

3.3V

5V

S0/S1/S2 States (Active)

1

0

3.3V

5V

S3

0

1

Note

Maintains Previous State

0

0

3.3V

0V

S4/S5 (ISL6504)

0

0

3.3V

5V

S4/S5 (ISL6504A)

NOTE: Combination Not Allowed.

DIAGRAM; ISL6504

5VSB

3.3V, 5V

S3

S5

5VDLSB

DLA

3V3DLSB

3V3DL

5VDL

DIAGRAM; ISL6504A

5VSB

3.3V, 5V

S3

S5

5VDLSB

DLA

3V3DLSB

3V3DL

5VDL

5VSB

3.3V,

S3

S5

1V2VID

DLA

1V5SB

5V, 12V

ISL6504, ISL6504A