“Semi Stand-By” To “Active” Flowchart Lcd With Preheat - Philips Q549.2E LA Service Manual

EN 22 5. Q549.2E LA
Constraints taken into account:
- Display may only be started when valid LVDS output clock can be delivered by the AVC .
- Between 5 and 50 ms after power is supplied, display should receive valid lvds clock .
- minimum wait time to switch on the lamp after power up is 200ms.
- To have a reliable operation of the backlight, the backlight should be driven with a PWM duty cycle of 100%
during the first second. Only after this first one or two seconds, the PWM may be set to the required output level
(Note that the PWM output should be present before the backlight is switched on). To minimize the artefacts, the
picture should only be unblanked after these first seconds.
The assumption here is that a fast toggle (<2s)
can only happen during ON ->SEMI ->ON. In
these states, the AVC is still active and can
provide the 2s delay. If the transition ON -> SEMI-
->STBY -> SEMI -> ON can be made in less than 2s,
the semi -> stby transition has to be delayed
CPipe already generates a valid output
clock in the semi -standby state: display
startup can start immediately when leaving
The higher level requirement is that audio and
video should be demuted without transient
effects and that the audio should be demuted
maximum 1s before or at the same time as the
unblanking of the video.
The higher level requirement is that the
ambilight functionality may not be switched on
before the backlight is turned on in case the
set contains a CE IPB inverter supply.
2009-May-08
Service Modes, Error Codes, and Fault Finding
until the requirement is met .
the semi-standby state.
Switch on the display by sending the
TurnOnDisplay(1) (I²C) command to the PNX5100
wait 250ms (min. = 200ms)
Switch off the dimming backlight feature, set
the BOOST control to nominal and make sure
PWM output is set to 100%
Switch on LCD backlight
Figure 5-7 "Semi Stand-by" to "Active" flowchart LCD with preheat
Semi Standby
Wait until previous on-state is left more than 2
seconds ago. (to prevent LCD display problems)
Assert RGB video blanking
and audio mute
(Lamp-ON)
Wait until valid and stable audio and video , corresponding to the requested
output is delivered by the AVC
AND
[the backlight PWM has been on for 1s (internal inverter LPL displays
OR the backlight PWM has been on for 2s (external inverter LPL displays)] .
Switch Audio-Reset low and wait 5ms
Release audio mute and wait 100ms before any other audio
handling is done (e.g. volume change)
Restore dimming backlight feature, PWM and BOOST output
and unblank the video.
Switch on the Ambilight functionality according the last status
settings.
Active
action holder: AVC
action holder: St-by
autonomous action
Initialize audio and video
processing IC's and functions
according needed use case.
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