Datasheet
EVALUATION MODULE
OPA3695
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............................................................................................................................................... SBOS355A – APRIL 2008 – REVISED SEPTEMBER 2008
impedance, but it is not required. Attention to the
To evaluate the OPA3695, an evaluation module
voltage appearing at each disable pin is required to
(EVM) is available. This EVM allows for testing the
ensure proper operation of this feature. The voltage
OPA3695 in many different systems. Inputs and
at the disable pin is shown in the Electrical
outputs include SMA connectors commonly found in
Characteristics section of this data sheet.
high-frequency systems along with 50 Ω characteristic
impedance traces. Because the traces are very short, This EVM is designed to be primarily used with split
changing the input and output terminations resistors supplies from ± 2.5V up to ± 6V. This EVM can be
from 49.9 Ω to 75 Ω has essentially no impact when used with a 5V single-supply up to 12V, but care
evaluating video signals. Several unpopulated must be taken to account for the input termination
component pads are found on the EVM to allow for resistor connections to ground. Adiitionally, the 100uF
different input and output configurations as dictated bypass capcitors C1 and C2 are rate at 10V. If single
by the user. supply is used with more than 10V applied, these
capacitors should be changed to accomodate the
By default, all channels of the EVM are configured for
increased supply voltage. The OPA3695 allowable
a noninverting gain of +2V/V. If inverting configuration
input range is defined in the Electrical Characteristics
or differential input configuration is desired, then
section of this datasheet and must be adhered to for
simply replacing R1, R4, and R7 with desired
proper operation. Also note that the gain setting
resistors allows these configurations to be set up
resistors are also connected to ground. Thus, any dc
quite easily. Also, the feedback and gain resistors
offset is increased proportionally by the gain. As
can be easily replaced to allow for any gain desired.
such, using the EVM as a split supply is
recommended even if the final use is single-supply.
Note that even though the default gain of the
Example: if the final usage is to be 12V single-supply,
OPA3695 is +2V/V, or 6dB, the output 49.9 Ω source
then using ± 6V supplies simplifies the dc reference
termination resistors (R13, R14, and R15) and the
voltage to mid-rail — or an equivalent 6V for a
user-applied 50 Ω end-termination resistance
single-supply configuration.
commonly found in test systems makes the overall
system gain appear as 0dB.
Figure 46 shows the OPA3695EVM schematic.
Figure 47 to Figure 50 illustrate the four layers of the
Each channel's disable control is independently
EVM PCB, incorporating standard high-speed layout
configured. By default, the use of jumpers JP1, JP2,
practices. Table 3 lists the Bill of Materials for the
and JP3 allows for a quick and easy method to
EVM as supplied from Texas Instruments.
evaluate the disable function of the OPA3695.
However, if this control must be externally controlled,
then using the SMA connectors J10, J11, and J12 is
recommended. The termination resistors R19, R20,
and R21 should to be changed to match the source
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Product Folder Link(s): OPA3695