ADA4410-6 Analog Devices, ADA4410-6 Datasheet - Page 14

• Manufacturer Part Number: ADA4410-6
• Manufacturer: Analog Devices

ADA4410-6
In single-supply applications, a positive output offset must be
applied to keep the negative-most excursions of the output
signals above the specified minimum output swing limit.
Figure 23 and Figure 24 illustrate several ways to use the
LEVEL1 and LEVEL2 inputs. Figure 23 shows an example of
how to generate fully adjustable LEVEL1 and LEVEL2 voltages
from ±5 V supplies. Figure 24 illustrates an effective way to
produce a 600 mV output offset voltage in a single-supply
application. Although the LEVEL1 input could simply be
connected to GND, Figure 24 includes bypassed resistive
voltage dividers for each input so that the input levels can be
changed, if necessary. Additionally, many in-circuit testers
require that I/O signals not be tied directly to the supplies or
GND. DNP indicates do not populate.
Figure 24. Setting Output Offsets to 600 mV on a Single Supply
9.53kΩ
9.53kΩ
9.09kΩ
Figure 23. Generating Fully Adjustable Output Offsets
DNP
1kΩ
1kΩ
0Ω
+5V
+5V
–5V
+5V
SINGLE SUPPLY
0.1µF
0.1µF
DUAL SUPPLY
DNP
LEVEL1
LEVEL1
LEVEL1
9.53kΩ
9.53kΩ
9.09kΩ
10kΩ
634Ω
1kΩ
1kΩ
+5V
+5V
–5V
+5V
0.1µF
0.1µF
0.1µF
LEVEL2
LEVEL2
LEVEL2
Rev. 0 | Page 14 of 16
INPUT AND OUTPUT COUPLING
Inputs to the ADA4410-6 are normally dc-coupled. Ac coupling
the inputs is not recommended; however, if ac coupling is
necessary, a suitable resistive network must be provided
following the ac coupling element to provide proper level
shifting and bias currents for the ADA4410-6 input stages.
The ADA4410-6 outputs can be either ac- or dc-coupled. As
discussed in the Output DC Offset Control section, the CV
output offset is different than the other outputs and is generally
ac-coupled.
PRINTED CIRCUIT BOARD LAYOUT
As with all high speed applications, attention to printed
circuit board layout is of paramount importance. Standard high
speed layout practices should be adhered to when designing
with the ADA4410-6. A solid ground plane is recommended,
and surface-mount ceramic power supply decoupling capacitors
should be placed as close as possible to the supply pins. All of
the ADA4410-6 GND pins should be connected to the ground
plane with traces that are as short as possible. Controlled
impedance traces of the shortest length possible should be used
to connect to the signal I/O pins and should not pass over any
voids in the ground plane. A 75 Ω impedance level is typically
used in video applications. All signal outputs of the ADA4410-6
should include series termination resistors when driving
transmission lines.
When the ADA4410-6 receives its inputs from a device
with current outputs, the required load resistor value for the
output current is most often different from the characteristic
impedance of the signal traces. In this case, if the intercon-
nections are sufficiently short (<< 0.1 wavelength), the trace
does not have to be terminated in its characteristic impedance.
Figure 25 shows an example in which the ADA4410-6 input
originates from DACs that require 300 Ω load resistors. Traces
of 75 Ω can be used in this instance, provided their lengths are
an inch or two at the most. This is easily achieved because the
ADA4410-6 and the device feeding it are usually adjacent to
each other, and connections can be made that are less than one
inch in length.