ST AN2705 handbook
Contents
1. Ti AN2705 Yy Application note TSH173 triple video buffer with filter for SD video evaluation board user guidelines Introduction This application note describes the TSH173 evaluation board designed to help you evaluate the TSH173 triple video buffer This document includes E A short description of the TSH173 video buffer including the internal block diagram E A description of the evaluation board and all of its components E The layout of the evaluation board About the TSH173 The 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 1TSH173 evaluation board Main features of the TSH173 4 5V to 5 5V single supply operation No input capacitor required R G B Y Pb Pr Y C CVBS driving Very low harmonic distortion 3 channels with 6dB gain buffer Each output can drive AC or DC coupled 150Q loads 3 video reconstruction filters for SD Tested on 5V power supply 3 internal input DC level shifter January 2008 Rev 1 1 8 www st com TSH173 description AN2705 1 TSH173 description Figure 2 1TSH173 internal block diagram Table 1 Pin description tone o IS q 2 8 AN2705 Evaluation board description 2 Evaluation board description This board is designed to be tested with a 75Q genera2. MILITARY AIR CRAFT SPACE LIFE SAVING OR LIFE SUSTAINING APPLICATIONS NOR IN PRODUCTS OR SYSTEMS WHERE FAILURE OR MALFUNCTION MAY RESULT IN PERSONAL INJURY DEATH OR SEVERE PROPERTY OR ENVIRONMENTAL DAMAGE ST PRODUCTS WHICH ARE NOT SPECIFIED AS AUTOMOTIVE GRADE MAY ONLY BE USED IN AUTOMOTIVE APPLICATIONS AT USER S OWN RISK Resale of ST products with provisions different from the statements and or technical features set forth in this document shall immediately void any warranty granted by ST for the ST product or service described herein and shall not create or extend in any manner whatsoever any liability of ST ST and the ST logo are trademarks or registered trademarks of ST in various countries Information in this document supersedes and replaces all information previously supplied The ST logo is a registered trademark of STMicroelectronics All other names are the property of their respective owners 2008 STMicroelectronics All rights reserved STMicroelectronics group of companies Australia Belgium Brazil Canada China Czech Republic Finland France Germany Hong Kong India Israel Italy Japan Malaysia Malta Morocco Singapore Spain Sweden Switzerland United Kingdom United States of America www st com q 8 8
3. or in LR1 Figure 6 Power supply AN2705 Schematic diagram and board components 3 Schematic diagram and board components Figure 7 Board components BNC_75R Je 7 BNC_75R BNCTF5R NA Figure 8 Full layout schematics SILu2 J BNC_75R q 5 8 6 8 Schematic diagram and board components AN2705 Table 2 List of board components 10 uF 1206 Bypass ceramic capacitor on Vcc 100 uF 0805 Bypass ceramic capacitor on Vcc C3 Sean diamei r Bypass chemical capacitor on Vcc not connected C4 0805 Bypass ceramic capacitor on Voc not connected Do Seco output capactor 2204F not connected rome fee sak A O supply conmecions e t o msm output resistor III output resistor III R2 R3 R9 Rio e R16 R17 0805 Bridge resistors not connected 0 Oom R4 R11 R18 0805 Strap when output is DC coupled R5 R7 R12 0805 Optional resistors to adapt output R14 R19 R21 impedance q AN2705 PCB layout 4 PCB layout Figure 9 Top layer Figure 10 Top layout TSHI73 TRIPLE VIDEO BUFFER Figure 11 Bottom layer COMPLIANT 2002 95 EC o Revision history Table 3 Document revision history os rem O 31 Jan 2008 Initial release 1974 718 AN2705 Please Read Carefully Information in this document is provided solely in connection with ST products STMicroelectronics NV and its subsidiaries ST reserve the right to make changes corrections modifications or imp
4. rovements to this document and the products and services described herein at any time without notice All ST products are sold pursuant to ST s terms and conditions of sale Purchasers are solely responsible for the choice selection and use of the ST products and services described herein and ST assumes no liability whatsoever relating to the choice selection or use of the ST products and services described herein No license express or implied by estoppel or otherwise to any intellectual property rights is granted under this document If any part of this document refers to any third party products or services it shall not be deemed a license grant by ST for the use of such third party products or services or any intellectual property contained therein or considered as a warranty covering the use in any manner whatsoever of such third party products or services or any intellectual property contained therein UNLESS OTHERWISE SET FORTH IN ST S TERMS AND CONDITIONS OF SALE ST DISCLAIMS ANY EXPRESS OR IMPLIED WARRANTY WITH RESPECT TO THE USE AND OR SALE OF ST PRODUCTS INCLUDING WITHOUT LIMITATION IMPLIED WARRANTIES OF MERCHANTABILITY FITNESS FOR A PARTICULAR PURPOSE AND THEIR EQUIVALENTS UNDER THE LAWS OF ANY JURISDICTION OR INFRINGEMENT OF ANY PATENT COPYRIGHT OR OTHER INTELLECTUAL PROPERTY RIGHT UNLESS EXPRESSLY APPROVED IN WRITING BY AN AUTHORIZED ST REPRESENTATIVE ST PRODUCTS ARE NOT RECOMMENDED AUTHORIZED OR WARRANTED FOR USE IN
5. tor and 7592 measurement tool Input signal must be between OV 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 adda resistor bridge to polarize the input signal at the right level as shown in Figure 3 Resistor bridge footprints are located on the back of the PCB Figure 3 TSH173 input Os BNC 75R SZ 13 ENC POR o BNC OR The TSH173 output can be AC coupled by a 220nF capacitor to minimize the DC component on the line To do this you must remove the R4 R11 and R18 zero ohm resistors and solder a 220uF capacitor on C6 C8 and C10 footprints as shown in Figure 4 Figure 4 TSH173 AC output 1974 3 8 Evaluation board description AN2705 If you connect a system with an input impedance other than 75Q to the PCB output a II resistor footprint on the board allows you to match impedances For example you connect a scope with a 50Q output impedance To match impedances you must add the following resistors R5 2 2kQ R6 1300 R7 820 The output can be AC or DC connected with this configuration Figure 5 TSH173 output impedance matching Power supply 4 8 Correct power supply bypassing is very important for optimizing performance A 10uF anda 100nF are soldered on the board This gives good performance However you can improve it by adding a 100uF capacitor in C3 and placing a 560uH coil instead of the zero ohm resist
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ST AN2705 handbook