Precision Instrumentation Amplifier
Evaluation Board
AD8222-EVALZ
Rev. 0
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FEATURES
Two AD8222 circuits
Dual channel
Differential out
Easy to connect screw terminals
Decoupled supply lines
Pads for RFI filtering
GENERAL DESCRIPTION
The AD8222-EVALZ has two AD8222 instrumentation
amplifier circuits: one circuit is configured for dual-channel
operation, while the other is configured for single-channel,
differential output operation. Inputs, outputs, references, and
the supplies are routed to screw terminals for easy connectivity.
The PCB board has four layers. The top and bottom layers are
used for routing, and the two internal layers are ground planes.
The ground plane was removed underneath the R
G
resistors.
This is a precaution against any capacitance mismatch at the
two R
G
pins, which may affect ac CMRR.
JUMPER SETTINGS
Table 1.
Jumpers Purpose
Default
J1A, J1B, J11
Connect inputs together
Unconnected
J2A, J2B, J12, J13
Connect reference pins to
ground
Connected
In the default factory setting, the reference pins of the AD8222
are connected to GND through J2A, J2B, J12, and J13.
Therefore, in the shipping configuration, W2A:REF1,
W2B:REF2, W13:REF2, and W13:+IN2 are connected to GND.
To disconnect the terminal from GND, remove the
corresponding jumper.
QUICK START
The quick start feature assumes that the jumpers are in their
factory default positions.
To begin:
•
Connect ground lead to GND.
•
Connect a 15 V supply to +V
S
.
•
Connect a −15 V supply to −Vs.
•
Ground −IN1.
•
Connect a 1V p-p, 1 kHz source signal to +IN1. A replica of
the signal should now appear at OUT1.
0
63
86
-00
1
Figure 1. AD8222-EVALZ Evaluation Board Photo
SETTING THE GAIN
The gain setting resistors are R1A and R1B for the dual-channel
part and R11A for the differential output part. The pads are
sized for 0603-sized resistors, although 0402 and 0805 sizes can
also be used.
EMI FILTERING
The board comes with 0603 component pads for an EMI filter.
These components are shown in Table 2.
Table 2.
Channel Components
Dual Channel A
R3A, R2A, C1A, C2A, C3A
Dual Channel B
R3B, R2B, C1B, C2B, C3B
Differential Output Channel
R13, R12, C11, C12, C13
The board, as shipped, does not contain EMI filtering. The
resistors pads are populated with 0 Ω resistors, and the
capacitors are not populated.
See the
data sheet for more information on EMI
filtering.
