AD7468BRT-R datasheet(25/28 Pages) AD

25 / 28 page

AD7466/AD7467/AD7468

Rev. C | Page 25 of 28

APPLICATION HINTS

GROUNDING AND LAYOUT

The printed circuit board that houses the AD7466/AD7467/

AD7468 should be designed such that the analog and digital

sections are separated and confined to certain areas. This facili-

tates the use of ground planes that can be separated easily. A

minimum etch technique is generally best for ground planes

because it gives the best shielding. Digital and analog ground

planes should be joined at only one place. If the devices are in a

system where multiple devices require an AGND to DGND

connection, the connection should still be made at one point

only, a star ground point, which should be established as close

as possible to the AD7466/AD7467/AD7468.

Avoid running digital lines under the device because these

couple noise onto the die. The analog ground plane should be

allowed to run under the AD7466/AD7467/AD7468 to avoid

noise coupling. The power supply lines to the devices should

use as large a trace as possible to provide low impedance paths

and to reduce the effects of glitches on the power-supply line.

Fast switching signals, like clocks, should be shielded with

digital ground to avoid radiating noise to other sections of the

board, and clock signals should never be run near the analog

inputs. Avoid crossover of digital and analog signals. Traces on

opposite sides of the board should run at right angles to each

other to reduce the effects of feedthrough on the board. A

microstrip technique is the best choice, but is not always

possible with a double-sided board. With this technique, the

component side of the board is dedicated to ground planes,

while signals are placed on the solder side.

Good decoupling is also very important. All analog supplies

should be decoupled with 10 μF tantalum in parallel with 0.1 μF

capacitors to AGND. All digital supplies should have a 0.1 μF

ceramic disc capacitor to DGND. To achieve the best perform-

ance from these decoupling components, the user should keep

the distance between the decoupling capacitor and the VDD and

GND pins to a minimum, with short track lengths connecting

the respective pins.

EVALUATING THE PERFORMANCE

OF THE AD7466 AND AD7467

The evaluation board package includes a fully assembled and

tested evaluation board, documentation, and software for

controlling the board from the PC via an evaluation board

controller. To evaluate the ac and dc performance of the

AD7466 and AD7467, the evaluation board controller can be

used in conjunction with the AD7466/AD7467CB evaluation

board and other Analog Devices evaluation boards ending in

the CB designator.

The software allows the user to perform ac tests (fast Fourier

transform) and dc tests (histogram of codes) on the AD7466

and AD7467. See the data sheet in the evaluation board package

for more information.

AD7468BRT-R 数据表(PDF) 25 Page - Analog Devices

AD7468BRT-R 数据表(HTML) 25 Page - Analog Devices

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28

数据表下载