ADC101S051 데이터 시트보기 (PDF) - TEXAS ADVANCED OPTOELECTRONIC SOLUTIONS

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ADC101S051

Single Channel, 200 to 500 ksps, 10-Bit A/D Converter

TEXAS ADVANCED OPTOELECTRONIC SOLUTIONS 

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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