ViewSonic Q7b Service Manual download pdf (Page 22)

ViewSonic Corporation Confidential - Do Not Copy Q7b-3

4. Circuit Description

A. A/D converters

The ADC is a 7-bit 4-channel analog-to digital converter ,the structure of these ADCS is 7-bit

successive approximation ,analog voltage is supplied from external sources to the A/D input pins and

the result of the conversion is stored In the 7-bit data latch registers(ADC0_REG~ADC3_REG).The

A/D cannels are activated by cleaning the correspondent control bits in the ADC_CON control register,

when users write”1” into one of the enable control bits(EN_ADC0~EN-ADC3),its correspondent I/O pin

will be switched to the A/D Converter input pin

The conversion will be started by setting STRT_ADC Bit, user can monitor this bit to get the valid A/D

channel, its latched data is meaningful, the analog voltage to be measured should be stable during the

conversion operation and the variation will not exceed 1 LSB for the best accuracy in measurement

B.Scalling controller

1. VGA front end

l Built-in triple high speed ADC,PLL for analog RGB input

l Supports both non-interlaced and interlaced RGB graphic input signals

l Input signal ranges from 0.55-0.9v

l Provides RGB analog gain and offset control

l Support 64 steps (one cycle of pixel)of phase adjust

l ADC sampling rates are up to 110MHZ for x type, 160MHZ for E type Supports analog SOG

input

2. YUV Front End

l Support ITU-R BT.656 8-bit input

l Built-in YUV to RGB color space converter

3. Display

l Supports data swap to fit any panel data alignment for PCB Layout

l Built in LVDS transmitter

l Supports spectrum of output clock

4. Hot interface

l Support serial 2-wire IIC bus

l Provides 2 channel PMW

5. Power

l Power supply

l Less than 1.3W

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ViewSonic Q7b Service Manual Page 22