4. Circuit Description
4.1 Power supply (DC/DC Converter):
4.1.1 IC251 BA9741 is a switching regulator controller that uses PWM method. That can be used for DC to DC
conversion for step-down. It converts a 24V DC into regulated and stable output voltage of 18V and 5V
respectively.
4.1.2 Regulator:
IC252 function is convert a 5V into regulated and stable O/P 3.3V.
IC253 function is convert a 5V into regulated and stable O/P 1.8V.
IC255 function is convert a 5V into regulated and stable O/P 3.3V.
IC256 function is convert a 5V into regulated and stable O/P 2.5V.
4.2 DDC data select:
4.2.1 IC601(AT24C02) is save D-SUB DDC data.
4.2.2 IC604(AT24C02) is save DVI-D, DDC data.
4.2.3 IC605(AT24C02) is save DVI-A, DDC data.
4.3 D-sub and DVI-A signal select
VP231wb analog source have D-sub and DVI-A signal input. User only one chose to display D-sub or DVI-A signal.
IC607(AD8186) is a R, G, B signal switch IC. If Control signal (RGBSEL) is high, LCD will display DVI-A.
If Control signal (RGBSEL) is low, LCD will display D-sub.
4.4 Scalar
The gm1601H is a dual channel graphics and video processing IC for Liquid Crystal Display (LCD) monitors and
televisions incorporating Picture in Picture, up to WUXGA output resolutions. The gm1601H provides all key IC
functions required for image capture, processing and display timing control. On-chip functions include a high speed
triple-ADC and PLL, Ultra-Reliable DVI receiver, high quality zoom, and shrink scaling engines, Motion Adaptive
De-interlacing (MADI), Low Angle Diagonal Interpolation (LADI), an on-screen display (OSD) controller, a 100MHz
on-chip X186 micro-controller (OCM), and a selectable double side TTL or dual channel LVDS transmitter for
interface to displays.
4.5 USB
IC951(USB20H04) is 4-Ports USB 2.0 Hub controller. It compliant with USB 2.0 specification. Enables bus-powered
Hi-Speed hub design. Compatible with On-The-Go (OTG) USB devices. Serial interface for configuration from
EEPROM or micro-controller when default is not used. Integrated termination and pull-up/pull-down resistors. Internal
short circuit protection of DP and DM lines. Supports individual or ganged over-current protection and power control.
ViewSonic Corporation Confidential
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Do Not Copy VP231wb
15
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