ADS8638_14 Datasheet, PDF (68/76 Pages) Texas Instruments – 12-Bit, 1MSPS, 4-/8-Channel, Bipolar-Input, SAR Analog-to-Digital Converter with Software-Selectable Ranges

ADS8634
ADS8638
SBAS541A – MAY 2011 – REVISED AUGUST 2011
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A common ground plane for both analog and digital often gives better results. Typically, the second printed circuit
board (PCB) layer is the ground plane. The ADC ground pins are returned to the ground plane through multiple
vias (PTH). It is a good practice to place analog components on one side and digital components on other side of
the ADC (or ADCs). All signals must be routed, assuming there is a split ground plane for analog and digital.
Furthermore, it is better to split the ground initially during layout. Route all analog and digital traces so that the
traces see the respective ground all along the second layer. Then, short both grounds to form a common ground
plane. Figure 97 Figure 98 show the reccomended layout around the ADS8638. The ADS8634 pinout is a subset
of the ADS8638 pinout. It is possible to make a common layout for the ADS8634/8 . Or, one can delete the
traces and components associated with the additional four channels of the ADS8638 to generate the ADS8634
layout.
Figure 97. Reccomended Layout for the ADS8638 Figure 98. Reccomended Layout for the ADS8638
(Top layer)
(Bottom layer)
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