ADC101S051CISDX View Datasheet(PDF) - TEXAS ADVANCED OPTOELECTRONIC SOLUTIONS
Part Name
Description
MFG CO.
ADC101S051CISDX
TEXAS ADVANCED OPTOELECTRONIC SOLUTIONS
'ADC101S051CISDX' PDF : 16 Pages View PDF
Applications Information (Continued)
9.0 POWER SUPPLY NOISE CONSIDERATIONS
The charging of any output load capacitance requires cur-
rent from the power supply, VA. The current pulses required
from the supply to charge the output capacitance will cause
voltage variations on the supply. If these variations are large
enough, they could degrade SNR and SINAD performance
of the ADC. Furthermore, discharging the output capaci-
tance when the digital output goes from a logic high to a logic
low will dump current into the die substrate, which is resis-
tive. Load discharge currents will cause "ground bounce"
noise in the substrate that will degrade noise performance if
that current is large enough. The larger the output capaci-
tance, the more current flows through the die substrate and
the greater is the noise coupled into the analog channel,
degrading noise performance.
To keep noise out of the power supply, keep the output load
capacitance as small as practical. It is good practice to use a
100 Ω series resistor at the ADC output, located as close to
the ADC output pin as practical. This will limit the charge and
discharge current of the output capacitance and maintain
noise performance.
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