ZHCSGI8A April 2017 – October 2021 ADC12D1620QML-SP
PRODUCTION DATA
Source all supply buses for the ADC from a common linear voltage regulator. This ensures that all power buses to the ADC are turned on and off simultaneously. This single source is split into individual sections of the power plane, with individual decoupling and connections to the different power supply buses of the ADC. Due to the low voltage but relatively high supply-current requirement, the optimal solution may be to use a switching regulator to provide an intermediate low voltage, which is then regulated down to the final ADC supply voltage by a linear regulator.
Power for the ADC must be provided through a broad plane, which is located on one layer adjacent to the ground plane(s). Placing the power and ground planes on adjacent layers provides low-impedance decoupling of the ADC supplies, especially at higher frequencies. The output of a linear regulator must feed into the power plane through a low-impedance, multi-via connection. The power plane must be split into individual power peninsulas near the ADC. Each peninsula must feed a particular power bus on the ADC, with decoupling for that power bus connecting the peninsula to the ground plane near each power/ground pin pair. Using this technique can be difficult on many printed circuit CAD tools. To work around this, 0-Ω resistors can be used to connect the power source net to the individual nets for the different ADC power buses. As a final step, the 0-Ω resistors can be removed, and the plane and peninsulas can be connected manually after all other error checking is completed.