Single-Supply, Low-Power,

Serial 8-Bit ADCs

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15

Layout, Grounding, and Bypassing

For best performance, use printed circuit boards. Wire-

wrap boards are not recommended. Board layout

should ensure that digital and analog signal lines are

separated from each other. Do not run analog and digi-

tal (especially clock) lines parallel to one another or run

digital lines underneath the ADC package.

Figure 10 shows the recommended system-ground

connections. A single-point analog ground (star-ground

point) should be established at the A/D ground.

Connect all analog grounds to the star ground. No digi-

tal-system ground should be connected to this point.

The ground return to the power supply for the star

ground should be low impedance and as short as pos-

sible for noise-free operation.

affect the comparator in the ADC. Bypass the supply to

the star ground with 0.1µF and 1µF capacitors close to

capacitor lead lengths for best supply-noise rejection. If

the power supply is very noisy, a 10

Ω resistor can be

connected to form a lowpass filter.

GND

+3V/+5V

SYSTEM POWER SUPPLIES

DGND

IN-

1

µF

10

Ω

0.1

µF

GND

DIGITAL

CIRCUITRY

MAX1106

MAX1107

Figure 10. Power-Supply Connections

Chip Information

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