AD7356BRUZ-RL Analog Devices Inc, AD7356BRUZ-RL Datasheet - Page 19

• Manufacturer Part Number: AD7356BRUZ-RL
• Description: 12-Bit Dual Diff Simult 5 MSPS ADC I.C.
• Manufacturer: Analog Devices Inc

Specifications of AD7356BRUZ-RL

• Design Resources: DC-Coupled, Single-Ended-to-Differential Conversion Using AD8138 and AD7356 (CN0041)
• Number Of Bits: 12
• Sampling Rate (per Second): 50k
• Data Interface: DSP, MICROWIRE™, QSPI™, Serial, SPI™
• Number Of Converters: 2
• Power Dissipation (max): 59mW
• Voltage Supply Source: Single Supply
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 16-TSSOP (0.173", 4.40mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

APPLICATION HINTS
GROUNDING AND LAYOUT
The analog and digital supplies to the AD7356 are independent
and separately pinned out to minimize coupling between the
analog and digital sections of the device. The printed circuit
board (PCB) that houses the AD7356 should be designed so
that the analog and digital sections are separated and confined
to certain areas of the board. This design facilitates the use of
ground planes that can be easily separated.
To provide optimum shielding for ground planes, a minimum
etch technique is generally best. The two AGND pins of the
AD7356 should be sunk in the AGND plane. The REFGND
pin should also be sunk in the AGND plane. Digital and analog
ground planes should be joined in only one place. If the
AD7356 is in a system in which multiple devices require an
AGND and DGND connection, the connection should still
be made at one point only, a star ground point that should
be established as close as possible to the ground pins on the
AD7356.
Avoid running digital lines under the device because this
couples noise onto the die. Allow the analog ground planes
to run under the AD7356 to avoid noise coupling. The power
supply lines to the AD7356 should use as large a trace as possible
to provide low impedance paths and reduce the effects of
glitches on the power supply line.
To avoid radiating noise to other sections of the board, shield
fast switching signals such as clocks, with digital ground; and
never run clock signals near the analog inputs. Avoid crossover
of digital and analog signals. To reduce the effects of feed-
through within the board, traces on opposite sides of the
Rev. 0 | Page 19 of 20
board should run at right angles to each other. A microstrip
technique is the best method but is not always possible with a
double sided board. In this technique, the component side of
the board is dedicated to ground planes and signals are placed
on the solder side.
Good decoupling is important; decouple all supplies with 10 μF
tantalum capacitors in parallel with 0.1 μF capacitors to GND.
To achieve the best results from these decoupling components,
they must be placed as close as possible to the device, ideally
right up against the device. The 0.1 μF capacitor, (including the
common ceramic types or surface-mount types) should have
low effective series resistance (ESR) and effective series induc-
tance (ESI). These low ESR and ESI capacitors provide a low
impedance path to ground at high frequencies to handle
transient currents due to logic switching.
EVALUATING THE AD7356 PERFORMANCE
The recommended layout for the AD7356 is outlined in the
evaluation board documentation. The evaluation board package
includes a fully assembled and tested evaluation board, docu-
mentation, and software for controlling the board from the PC
via the converter evaluation and development board (CED).
The CED can be used in conjunction with the AD7356 eval-
uation board (as well as many other evaluation boards ending
in the ED designator from Analog Devices, Inc.) to demonstrate/
evaluate the ac and dc performance of the AD7356.
The software allows the user to perform ac (fast Fourier transform)
and dc (linearity) tests on the AD7356. The software and docu-
mentation are on a CD shipped with the evaluation board.
AD7356