MAX189ACWE(2012) View Datasheet(PDF) - Maxim Integrated

Part Name

Description

Manufacturer

MAX189ACWE
(Rev.:2012)

+5V, Low-Power, 12-Bit Serial ADCs

Maxim Integrated 

MAX187/ MAX189

+5V, Low-Power, 12-Bit Serial ADCs

Layout, Grounding, 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 digital (especially

clock) lines parallel to one another, or digital lines under-

neath the ADC package.

Figure 17 shows the recommended system ground con-

nections. A single-point analog ground (“star” ground

point) should be established at GND, separate from the

logic ground. All other analog grounds should be con-

nected to this ground. The 16-pin versions also have a

dedicated DGND pin available. Connect DGND to this

star ground point for further noise reduction. No other

digital system ground should be connected to this single-

point analog ground. The ground return to the power

supply for this ground should be low impedance and as

short as possible for noise-free operation.

High-frequency noise in the VDD power supply may

affect the ADC’s high-speed comparator. Bypass this

supply to the single-point analog ground with 0.01FF

and 4.7FF bypass capacitors. Minimize capacitor lead

lengths for best supply-noise rejection. If the +5V power

supply is very noisy, a 10I resistor can be connected

as a lowpass filter to attenuate supply noise (Figure 17).

SUPPLIES

+5V

GND

R* = 10I

4.7µF

0.01µF

VDD

AGND

MAX187

MAX189

*OPTIONAL

DGND

+5V DGND

DIGITAL

CIRCUITRY

Figure 17. Power-Supply Grounding Condition

Maxim Integrated

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