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ADS5545 Datasheet(PDF) 44 Page - Texas Instruments |
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ADS5545 Datasheet(HTML) 44 Page - Texas Instruments |
44 / 54 page ![]() www.ti.com Board Design Considerations Grounding Supply Decoupling Series Resistors on Data Outputs Exposed Thermal Pad ADS5517 SLWS203 – DECEMBER 2007 A single ground plane is sufficient to give good performance, provided the analog, digital and clock sections of the board are cleanly partitioned. See the EVM User Guide (SLWU028) for details on layout and grounding. As the ADS5517 already includes internal decoupling, minimal external decoupling can be used without loss in performance. Note that decoupling capacitors can help to filter external power supply noise, so the optimum number of capacitors would depend on the actual application. The decoupling capacitors should be placed close to the converter supply pins. It is recommended to use separate supplies for the analog and digital supply pins to isolate digital switching noise from sensitive analog circuitry. If only a single 3.3V supply is available, it should be routed first to AVDD. It can then be tapped and isolated with a ferrite bead (or inductor) with decoupling capacitor, before being routed to DRVDD. It is recommended to put series resistors (50 to 100 Ω) on each output line placed close to the converter pins. This helps to isolate the outputs from seeing large load capacitances and in turn reduces the amount of switching noise. It is necessary to solder the exposed pad at the bottom of the package to a ground plane for best thermal performance. For detailed information, see application notes QFN Layout Guidelines (SLOA122) and QFN/SON PCB Attachment (SLUA271). 44 Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s): ADS5517 |