Analog Devices │
6
MAX22005PMB#
Evaluates: MAX22005
14)
Press
Sample Continuously
. You should see volt
-
age values in the
Results
box close to what is in
. Press
Stop Sampling
.
15) The current measurements are performed one chan
-
nel at a time. Disable and/or remove the voltage
source. Select only the
Channel 1
box in the
Mea-
surement Configuration
. In
Results
, click the
Volt-
age/Current
button for
Channel 1
so that it slides to
the right (colored blue). See
. Note that it is
possible to measure all four channels at once with
four different current sources.
16) Connect a current source between CH1 (Pin 1) and
the adjacent GND pin (Pin 3). Set the current source to
+20mA and activate it. Press
Sample Continuously
in
the
Sample
box. You should see a
Channel 1
current
measurement result similar to that shown in
.
Press
Stop Sampling
.
17) Then, apply -20mA from the current source and
confirm that the current value in
Results
matches.
(Note: For higher accuracy in current mode, all
channels must be calibrated to accommodate the
real sense resistor values. The initial accuracy of the
sense resistors is 0.1%, which is much higher than
the target of 0.02% Total Unadjusted Error. Refer to
the MAX22005 data sheet for a description of the
calibration procedure.)
18) Repeat steps 15 through 17 for Channels 2, 3, and 4,
if desired.
Detailed Description of Hardware
The MAX22005 is a twelve-channel industrial-grade ana
-
log input voltage mode device that can also be configured
as an analog input current mode device using an external
precision resistor per channel. It can also operate as a
multifunctional “universal” analog input using an external
precision resistor and a low-cost switch per channel. The
MAX22005 features an integrated 24-bit delta-sigma ADC
that is shared between all analog inputs. The MAX22005
measurements have a Total Unadjusted Error (TUE) of
0.02% Full Scale Range (FSR) at 25°C factory calibration
and a TUE of 0.05% FSR over ±50°C from 25°C factory
calibration.
The MAX22005PMB# hardware provides everything
needed to evaluate the MAX22005 using the Pmod inter
-
face. An optional USB2PMB2# or USB2GPIO# adapter
can be used with the Munich GUI to provide the USB-to-
SPI interface to communicate with the MAX22005. The
MAX22005PMB# is configurable as 8 single-ended ana
-
log voltage inputs, 4 single-ended analog current inputs,
4 differential analog voltage inputs, 4 multifunctional
(universal) analog inputs, or combinations thereof. Note
that these configurations are a subset of the total configu
-
rations possible with the MAX22005 IC. For greater flex
-
ibility and access to all of the MAX22005 features, refer to
the MAX22005 Evaluation Kit.
Figure 7. Example Current Measurement Settings and Expected Results
