??1qla?|3--?q weltrend semiconductor, inc. s |? ? ? ?? u ~ ? ? u ~ af e ?? 24 ?1 2 ? 2f, no. 24, industry e. 9 th rd., science-based industrial park, hsin-chu, taiwan tel :886-3-5780241 fax:886-3-5794278.5770419 WT9101 video amplifier system with osd & dacs data sheet preliminary rev. 0.92 feb, 5, 2002 the information in this document is subject to change without notice. weltrend semiconductor, inc. all rights reserved.
WT9101 data sheet rev. 0.92 weltrend semiconductor, inc. page 2 general description the WT9101 pre-amp is an integrated cmos crt pre-amp. the ic is i 2 c compatible, and allows control of all the parameters necessary to directly setup and adjust the gain and contrast in the crt display. brightness and bias can be controlled through the dac outputs. black level clamping of the signal is carried out directly on the ac coupled input signal into the high impedance preamplifier input, thus eliminating the need for the additional black level clamp capacitors. the ic is packaged in an industry standard 24-lead dip molded plastic package. features 110 mhz bandwidth preamplifier with full video signal parametric control. i 2 c compatible interface to micro-controller. 4 external 8-bit dacs for bus controlled bias and brightness. on screen display(osd) mixing. auto beam current limiting. suitable for use with discrete or integrated clamp, with software configurable brightness mixer. power save (green) mode, 80% power reduction. block diagram and c onnection diagram v out v h flyback clamp abl b osd osd select r video g video b video analog gnd ref 1 2 3 4 5 6 7 8 9 10 11 12 r osd g osd vcc r ext sda scl osd contrast hi z input buffer amp contrast auto beam limit amp osd mixer gain output buffer amp dc dacs offset registers v ref i 2 c interface dacs clamp dc restore amp h blank 24 23 22 21 20 19 18 17 16 15 14 13 to other video channels v ref r out g out b out digital gnd dac1 dac2 dac3 dac4 v
WT9101 data sheet rev. 0.92 weltrend semiconductor, inc. page 3 pin description pin no. pin name description 1 2 3 red osd input green osd input blue osd input these inputs accept standard ttl or cmos inputs. each color is either fully on (logic high) or fully off (logic low). unused pins should be connected to ground with a 47k resistor. 4 osd select this input accepts a standard ttl or cmos input. h = osd l = video connect to ground with a 47k resistor if not using osd. 5 6 7 red video in green video in blue video in video inputs. these inputs must be ac coupled with a 0.047f cap. dc restoration is done at these inputs. a series resistor of about 33 [ and external esd protection diodes should also be used for esd protection. 8 analog ground ground pin for the analog circuits of the WT9101 9 vcc power supply pin for WT9101 10 v ref r ext sets the internal current sources through a 10 k [ 1% external resistor. resistor value and accuracy is critical for optimum operation of the WT9101 11 sda the i 2 c data line. a pull-up resistor of about 2 [ should be connected between this pin and +5v. a 300 [ resistor should be connected in series with the data line for protection against arcing. 12 scl the i 2 c clock line. a pull-up resistor of about 2k [ should be connected between this pin and +5v. a 300 [ resistor should be connected in series with the clock line for protection against arcing. 13 14 15 16 dac4 dac3 dac2 dac1 dac outputs for cathode cut-off adjustments and brightness control. dac 4 can be set to change the outputs of the other three dacs, acting as the brightness control. the dacs are set through the i 2 c bus. 17 digital ground ground pin for the digital circuits of the WT9101 18 19 20 blue video out green video out red video out video outputs of the WT9101. the ideal driver for this part is crt driver, which has the necessary gain of 26 db or 20 v/v. 21 v ref out a 0.1f capacitor must be placed close to this pin for decoupling the internal vref. this pin may be used for an external voltage reference with proper buffering 22 abl the auto beam limit control reduces the gain of the video amplifier in response to a control voltage proportional to the crt beam current. the abl acts identically on all three channels. abl is required for crt life and x-ray protection
WT9101 data sheet rev. 0.92 weltrend semiconductor, inc. page 4 pin no. pin name description 23 clamp pulse this input accepts a standard ttl or cmos input. a positive signal activates the clamp pulse for dc restoration of the video input. the ac coupling capacitors at the video inputs are used for holding the dc correction voltage, eliminating the need for additional capacitors 24 h flyback h flyback is an analog signal input from the monitor horizontal scan. the WT9101 is able to generate an accurate blanking pulse in the video outputs from this input. the horizontal flyback from the monitor must be a clean signal, with no ringing or other noise on the signal
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