Datasheet

ADS807

SBAS072A

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FIGURE 8. Recommended Bypassing for the Supply Pins.

performance. All ground connections on the ADS807 are

internally joined together eliminating the need for split ground

planes. The ground pins (1, 20, 26) should directly connect

to an analog ground plane which covers the PC board area

under the converter. While designing the layout, it is impor-

tant to keep the analog signal traces separated from any

digital lines to prevent noise coupling onto the analog signal

path. Because of the its high sampling rate, the ADS807

generates high frequency current transients and noise (clock

feedthrough) that are fed back into the supply and reference

lines. This requires that all supply and reference pins are

sufficiently bypassed. Figure 8 shows the recommended

decoupling scheme for the ADS807. In most cases, 0.1µF

ceramic chip capacitors at each pin are adequate to keep the

impedance low over a wide frequency range. Their effective-

ness largely depends on the proximity to the individual

supply pin. Therefore, they should be located as close to the

supply pins as possible. If system supplies are not a low

enough impedance, adding a small tantalum capacitor will

yield the best results.

0.1µF

NOTE: (1) Optional.

0.1µF

10µF

(1)

+5V +3V/+5V

0.1µF

GND

1, 20

27 15 26

GND VDRV

ADS807