4-4. DISPLAY POWER MANAGEMENT circuits
(1) Stand-by / Suspend state:
When receiving no horizontal or vertical sync signal for 6 seconds, the output voltage of pin 25 of IC801 turns
to 5V from 0V and Q903 is turned off. The output voltage of IC903 (12Vreg.) turns to 1.2V from 12V and then
the circuit controlled by 12V stops operation. Therefore, it keeps the power consumption 10W or less.
(2) Active-off state:
When receiving no horizontal and vertical sync signals for 6 seconds, the output voltage of pin 27 of IC801
turns to 5V from 0V and Q904 is turned on. The D914 starts operation and the output voltage of T901
secondary declines to approx. 7%. All circuits except for the 5V line stop and it keeps the power consumption
3W or less. In this case, as an input voltage of IC906 is supplied from the 80V line, the circuit controlled by
5V is activated.
<Power save control signals>
PS1PS2
ModeSync signalCircuit
IC801 pin 27IC801 pin 25
NormalH,V-Sync, VIDEO: ONLOWHIGHAll circuits are activated.
Stand-byV-Sync, VIDEO: OFFHIGHHIGH12V circuit stops.
SuspendH-Sync, VIDEO: OFFHIGHHIGH
Active-offH,V-Sync, VIDEO: OFFHIGHLOWAll circuits except for 5V line stop.
4-5. SYNC SIGNAL PROCESSING circuit
The input signal from D-SUB connector is input to pins 41 (H) and 42 (V) of IC801. The input sync signal is
waveform-shaped and output from pins 39 (H) and 40 (V), and then supplied to pins 26 (H) and 27 (V) to control the
horizontal and vertical deflection.
The input sync signal to IC801 is processed by SYNC SIGNAL PROCESSING circuit in IC801 as follows:
Detect the input sync signal presence
Discriminate the input sync signal type: Separate / Composite
Discriminate the sync polarity: Positive / Negative
Count the frequency
Counting criterion: X'TAL 12MHz
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ACEC
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