ZXFV302EV 4:1 CHANNEL VIDEO MULTIPLEXER EVALUATION BOARD Evaluation board description Figures 1, 2 and 3 show the schematic and copper layout of a double-sided printed circuit board suitable for evaluation of the device in the laboratory. The wide bandwidth of the ZXFV302 4:1 channel video multiplexer necessitates some care in the layout of the printed circuit. For this reason Zetex has made available an Evaluation Board. BNC connector sockets allow connection to test instruments via 50 cables. The output circuit includes a resistor matching circuit to present a load of 150 to the amplifier (equivalent to a 75 back-terminated video line) and simultaneously provide 50 output impedance. The Evaluation Board layout serves as a useful example for many applications, showing a practical implementation of the advice given below. The ZXFV302EV can also be used to evaluate the ZXFV301 4:1 channel multiplexer. The ZXFV301 and ZXFV302 devices have very similar ac performance, with the only difference being in the active channel selection. The attenuation of this matching circuit is 15.45 dB. As the multiplexer is internally configured for a voltage gain of 1, the overall gain from input to output is -15.45dB. Figure 1 Circuit schematic ISSUE 1 - SEPTEMBER 2004 1 SEMICONDUCTORS ZXFV302EV PCB design A continuous ground plane is required under the device and its signal connection paths, to provide the shortest possible ground return paths for signals and power supply filtering. A double-sided or multi-layer PCB construction is required, with plated-through via holes providing closely spaced low-inductance connections from some components to the continuous ground plane (some of these holes are not visible in the figures for the Evaluation Board - artworks and NC drill output can be provided if required). Figure 2 Evaluation circuit top copper layout (overall dimensions 2.5 x 2.25 inches) Figure 3 Evaluation board bottom copper layout (viewed through from top) ISSUE 1 - SEPTEMBER 2004 SEMICONDUCTORS 2 ZXFV302EV Evaluation board parts list Power supply filtering For the power supply filtering, low inductance surface mount capacitors are normally required. It has been found that very good RF decoupling is provided on each supply using a 1000pF NPO size 0805 or smaller ceramic surface mount capacitor, closest to the device pin, with an adjacent 0.1F X7R capacitor. Other configurations are possible and it may be found that a single 0.01F X7R capacitor on each supply gives good results. However this should be supported by larger decoupling capacitors elsewhere on the printed circuit board. Values of 1 to 10F are recommended particularly where the voltage regulators are located more than a few inches from the device. These larger capacitors are recommended to be solid tantalum electrolytic or ceramic types. QTY CCT - REF VALUE DESCRIPTION Resistors, surface mount 1 R1, 51R 0805 2 R2,R3 1k 0805 1 R4 120R 0805 1 R5 10R 0805 1 R6 62R 0805 4 R1 to R4 51R 0805 4 R5 to R8 22k 0805 1 R9 120R 0805 1 R10 62R 0805 1 R11 10R 0805 5 R12 - R16 47k 0805 Capacitors, surface mount 2 1nF 50V ceramic 0805 NPO 6 100nF 25V ceramic 0805 XR7 2 10F 16V Tant Elec size C Integrated circuits 1 U1 Zetex ZXFV302N16 Miscellaneous 5 BNC socket, PCB straight flange, e.g. Tyco B35N14H999X99 1 3-way PCB screw terminal block IMO 20.501/3SB 1 10 SW1 DIL switch, 8 way TP1 to TP10 PCB test terminal, red, W.Hughes 100-107 (c) Zetex Semiconductors plc 2004 Europe Americas Asia Pacific Corporate Headquaters Zetex GmbH Streitfeldstrae 19 D-81673 Munchen Germany Zetex Inc 700 Veterans Memorial Hwy Hauppauge, NY 11788 USA Zetex (Asia) Ltd 3701-04 Metroplaza Tower 1 Hing Fong Road, Kwai Fong Hong Kong Zetex Semiconductors plc Zetex Technology Park, Chadderton Oldham, OL9 9LL United Kingdom Telefon: (49) 89 45 49 49 0 Fax: (49) 89 45 49 49 49 europe.sales@zetex.com Telephone: (1) 631 360 2222 Fax: (1) 631 360 8222 usa.sales@zetex.com Telephone: (852) 26100 611 Fax: (852) 24250 494 asia.sales@zetex.com Telephone (44) 161 622 4444 Fax: (44) 161 622 4446 hq@zetex.com These offices are supported by agents and distributors in major countries world-wide. This publication is issued to provide outline information only which (unless agreed by the Company in writing) may not be used, applied or reproduced for any purpose or form part of any order or contract or be regarded as a representation relating to the products or services concerned. The Company reserves the right to alter without notice the specification, design, price or conditions of supply of any product or service. For the latest product information, log on to www.zetex.com ISSUE 1 - SEPTEMBER 2004 3 SEMICONDUCTORS