WT8045

Synchronous

Signal

Discriminator

and

Power Saving Detector for Green Monitor





Weltrend

Semiconductor,

Inc.

2F., No. 24, Industry E. 9th Rd.

Science-Based Industrial Park

Hsin-Chu, Taiwan, R.O.C.

Tel:

886-35-780241

Fax: 886-35-770419

13

APPLICATION DESCRIPTION

DPMS (Display Power Management Signaling) Detection

As per DPMS proposal version 1.0P, revision 0.54P, WT8045 provides Monitor Power

Management Detection Circuit for the convenience of monitor designers in designing power

saving monitors, or the so called "Green Monitors". Please refer to the table 1 as below for

power states defined in the DPMS.

DPMS requires at least 5 seconds delay before transition from ON state to any power saving

state, to avoid unintentionally entering a power saving state during display resolution changes

and timing mode changes. And it can be done instantaneously, for the transition between any

power saving state.

Table 1 Display Power Management Summary

State

Signals

DPMS

Compliance

Power

Savings

Recovery

Time

Horizontal

Vertical

Video

Requirement

On

Pulses

Pulses

Active

Mandatory

None

Not

Applicable

Stand-by

No Pulses

Pulses

Blanked

Optional

Minimal

Short

Suspend

Pulses

No Pulses Blanked

Mandatory

Substantial

Longer

Off

No Pulses No Pulses Blanked

Mandatory

Maximum

System

Dependent

*

"No-Pulse" represents the frequency of Hsin or Vsin less than or equal to 10Hz, but

"Pulses" represents that frequency of Hsin greater than or equal to 10KHz and Vsin

greater than or equal to 40Hz