Using Voltage Source As Input - Analog Devices EVAL-ADA4351-2 User Manual

User Guide
GETTING STARTED

USING VOLTAGE SOURCE AS INPUT

Because the ADA4351-2 is a PGTIA, the EVAL-ADA4351-2EBZ is
configured by default to follow a TIA circuit, expecting a current
input. The EVAL-ADA4351-2EBZ, however, provides options which
allow user to configure the circuit differently. To cater to voltage
inputs, the user can make changes and setup the circuit as an
inverting amplifier.
Take the following steps to simply setup the EVAL-ADA4351-2EBZ
as an inverting amplifier with a gain of −0.08 and a gain of −1:
1. Configure and connect the power supplies to be used. For this
quick start, set the supplies to single-supply operation by using
the following settings:
AVDD (analog positive supply voltage): 5 V, 0.1 A
►
AVSS (analog negative supply voltage): 0 V, 0.1 A
►
DVDD (digital positive supply voltage): 1.8 V, 0.1 A
►
2. Install a new resistor on the input of each channel (R4 for
Channel A and R16 for Channel B).
Note that by default, R4 and R16 have a 0 Ω resistor
►
installed. Change the resistor values on R4 and R16 to 499
kΩ to get a gain of −0.08 and −1, respectively.
3. Configure the DC voltage source for use as input. Set this
source to 2 V. Connect this source to J1 for Channel A or J4 for
Channel B.
4. Configure another DC voltage source for use as reference
voltage. Set this source to 1.25 V. Connect this source to J2 for
Channel A or J3 for Channel B.
With the default gain setting (P5 or P4 open), the reference
►
sets to 1.35 V.
With a shunt installed at P5 for Channel A or P4 for Channel
►
B, the reference sets 2.5 V.
5. Connect the output, J5 for Channel A or J6 for Channel B, to a
DMM.
6. Retain the default gain settings. Leave P5 or P4 open for a gain
of −0.08. The equivalent test circuit is shown in
7. Enable the sources as follows:
Turn on the power supply for the analog and digital supplies.
►
Turn on the DC voltage source used as a reference voltage.
►
Turn on the DC voltage source for the input.
►
8. Record the measured output as shown in the DMM.
9. Install a shunt on P5 or P4 to set the gain to −1. The equivalent
test circuit is shown in Figure
10. Record the measured output as shown in the DMM.
Table 6 provides the summary of the initial setup for the DC voltage
source input configuration. The expected results for both tests are
shown in Table 7.
Table 6. Configuring the ADA4351-2 for Single-Supply Operation
Parameter Status
AVDD 5 V.
analog.com
Figure 6.
7.
Description
Single-supply operation.
EVAL-ADA4351-2
Table 6. Configuring the ADA4351-2 for Single-Supply Operation (Continued)
Parameter Status
AVSS 0 V.
DVDD 5 V.
P5 and P4 Open.
R4 and R16 Install 499 kΩ on these
resistors.
J2 and J3 Set DC inputs to 1.25 V.
J1 and J4 Set the DC source inputs
to 2 V.
J5 and J6 Connect both to a DMM.
Figure 6. DC Voltage Source Input Test Circuit, Default Gain State
Figure 7. DC Voltage Source Input Test Circuit, Shunt installed at P4 and P4
Table 7. Expected Outputs for the Voltage Source Input Test
Voltage Input (V) SW SEL x
2 Low (no jumper)
2 High (jumper installed)
Description
Single-supply operation.
Single-supply operation.
Default feedback resistor (R ) setting.
F
Sets the inverting gain.
Sets the reference.
Sets the input.
Displays the output.
Expected Output (V)
1.1896
0.5
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