Dell 1907FPf - Power On;Off Sequency

Service Manual
9
3.2 Digital
Standard Resolution Horizontal Frequency
(KHz)
Vertical Frequency
(Hz)
640 x 480 31.469 59.940
800 x 600 37.879 60.317
1024 x 768 48.363 60.004
VESA
1280x1024 48.483 60.042
4. Power On/Off Sequency
Hardware Power ON
When power cord plug into AC socket, Power provides 12V. DC_5V, DC_3.3V generate from DC_12V
through LDO U851.DC_5V is voltage for panel and USB IC U901, DC_3.3v is main voltage for U401.
When DC_3.3V input to U401, U401 reset circuit active, set U401 all registers to default,. That means
finish hardware power on.
Software Power ON/OFF
When press power key, U401 #125 recieves low pulse, and then (gm5621-LF) U401 will be wake up
and send high puls(at 127,49pin) to on CCFL and switch 5.0v to panel module. And make the VGA cable
input signal source display normal on panel.
- If Power ON, U402 #51 (LED_Green) will send out High potential, and then LED green on.
- If Power OFF, U402 #57 (LED_Amber) will send out High potential, and then LED Amber on.
The Panel_Vcc, Backlight_En, CLK/DATA output to panel will follow the following sequency.
Power supply for V
DD
90% 90%
10%
0V 10%
T1 T2
T5 T6 T7
Signals Valid data
(Digital RGB, HS, VS, DE, CLOCK)
0V
T3 T4
Power supply for back light
T1(ms) T2 (ms) T3 (ms) T4 (ms) T5 (ms) T6 (ms) T7(ms)
SPEC(AU)
0.0~10 0.5~50 >200 >200 0.5~50 0.5~10 >1000
SPEC(LPL)
0.5~10 0~50 >200 >200 0.0~50 0.5~10 >1000