HP WF1907 Service Manual page 5

3.2.6 Q301, R301, R302, R304 : Adjust back light luminance of LCD module
It is adjusted back light luminance control (BKLT_ADJ) is performed for the back light
luminance. The BKLT_ADJ signal is generated from I306 scaler IC Gm5726H (Gm5766H).
3.3 VGA & DDC interface (Circuit diagrams sheet 4 of 8)
This sheet has RGB analog video and H/V sync signals input from VGA connector.
The RGB analog video signals input through AC-coupled, analog video signal is used to clamp the
black level at 0V. And H/V sync to sclaer.
Support EDID plug & play function for analog video.
It is to support VESA DDC/CI interface for analog video.
3.3.1 P302 connector
The RGB analog video and H/V sync input signals to I306 scaler Gm5726H (Gm5766H).
The VESA DDC/CI function is through I2C bus to I306 scaler Gm5726H (Gm5766H).
3.3.2 I304 : EDID EEPROM (24LC02B)
The I304 is support EDID information of the VESA standard for VGA interface, and support
plug and play for the PC host.
3.4 DVI & DDC interface (Circuit diagrams sheet 5 of 8)
The digital video signals (TMDS) input from P303 DVI-D connector. The digital video signal is
TMDS for DVI V1.0 standard. And support EDID plug & play function for digital video.
It is to support VESA DDC/CI interface, and support HDCP function.
3.4.1 P303 connector
P303 is DVI-D connector for DDWG standard, it have digital video signals (TMDS) to I306
scaler Gm5726H (Gm5766H). The VESA DDC/CI function is through I2C bus to I306
Gm5726H (Gm5766H). And support HDCP function is also through I2C bus to I306
Gm5726H (Gm5766H).
3.4.2 I305 : EDID EEPROM (24LC02B)
The I305 is support EDID information of the VESA standard for DVI interface, and support
plug and play for the PC host.
3.5 Scaler Gm5726H (Gm5766H) (Circuit diagrams sheet 6 of 8)
The I306 Gm5726H (Gm5766H) is all-in-one LCD monitor controller. The Gm5726H (Gm5766H)
leverages Genesis patented advanced image-processing technology as well as a proven
integrated ADC/PLL and an Ultra-Reliable DVI compliant receiver to provide excellent image
quality. Gm5726H (Gm5766H) also integrates HDCP function, a micro-controller, an OSD
controller, and dual LVDS.
The RGB analog video signal from video input circuit enter to incorporated A/D converted block
(ADC) into the digital data for analog video signal.
The TMDS digital signals input (with HDCP) entered from the DVI-D connector is converted into
the digital data.
Based on this conversion, this device performs interpolation during pixel extension. These
interpolation digital data are transformed to LVDS signal. The I306 source voltage is 3.3V and
1.8V, the device clock source frequency is 14.318 MHz. And support DDC/CI interface of VESA
and function key operation.
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