description of the TSH173 video buffer, including the internal block diagramA description of the evaluation board and all of its componentsThe layout of the evaluation boardAbout the TSH173The TSH173 is a single supply triple video buffer featuring an internal gain of 6dB and an internal low pass filter of 8.2MHz cut-off frequency for each channel to fit with Standard Definition requirements for video line interfaces.Figure 1.TSH173 evaluation boardMain features of the TSH173 4.5V to 5.5V single supply operationNo input capacitor requiredR-G-B, Y-Pb-Pr, Y-C-CVBS drivingVery low harmonic distortion3 channels with 6dB gain bufferEach output can drive AC- or DC-coupled 150 loads3 video reconstruction filters for SD Tested on 5V power supply3 internal input DC level shifterwww.st.comTSH173 descriptionAN27052/8 1 TSH173 descriptionFigure 2.TSH173 internal block diagram Table 1.Pin descriptionNamePin numberDescriptionIN1, IN2, IN31, 2, 3Input pinsOUT1, OUT2, OUT38, 7, 6Output pins+VCC4Positi features of the TSH173 4.5V to 5.5V single supply operationNo input capacitor requiredR-G-B, Y-Pb-Pr, Y-C-CVBS drivingVery low harmonic distortion3 channels with 6dB gain bufferEach output can drive AC- or DC-coupled 150 loads3 video reconstruction filters for SD Tested on 5V power supply3 internal input DC level shifterwww.st.comTSH173 descriptionAN27052/8 1 TSH173 descriptionFigure 2.TSH173 internal block diagram Table 1.Pin descriptionNamePin numberDescriptionIN1, IN2, IN31, 2, 3Input pinsOUT1, OUT2, OUT38, 7, 6Output pins+VCC4Positive supplyGND5GroundAN2705Evaluation board description 3/82 Evaluation board descriptionThis board is designed to be tested with a 75 generator and 75 measurement tool. Input signal must be between 0V and 1.4V so that it is not clamped. Otherwise, you must replace the zero ohm resistor by a 100nF capacitor in CR1, CR2, and CR3, and add a resistor bridge to polarize the input signal at the right level as shown in Figure3. Resistor bridge footprints are loc January 2008 Rev 11/8AN2705Application noteTSH