CN0336 Datasheet, PDF (5/7 Pages) Analog Devices – Devices Connected

Circuit Note
CN-0336
J2
D1
I_IN ^1N4148
INPUT
0mA TO 20mA
TP1
0.1V TO 2.4V
V_IN
R2
C11
51Ω
4.7nF
R3
120Ω _{GND_ISO}
U2
ADuM5401
(C-GRADE)
+3.3V
+3.3V
V_ISO
V_DD1
GND_ISO GND1
REF_OUT V_DD
CS
V_OA
V_IA
U3
AD7091R
SCLK
CONVST
V_OB
V_IB
V_OC
V_IC
SDO
V_ID
V_OD
GND REGCAP V_DRIVE
C8
1µF
+3.3V
V_SEL
GND_ISO
GND_ISO
RC_OUT
GND1
+3.3V_IN
GND
SS
SCK
CONVST
MISO
GND
PMOD CON
12-PIN
J1
GND_ISO
GND_ISO
Figure 4. 0 mA-to-20 mA Single Supply Analog to Digital Conversion with Isolation (All Connections and Decoupling Not Shown)
The AD7091 is similar to the AD7091R, but without the voltage
reference output, and the input range is equal to the power
supply voltage. The AD7091 can be used with a 2.5 V ADR391
reference. The ADR391 does not require buffering, therefore a
single AD8605 can be used in the circuit.
The ADR391 is a precision 2.5 V band gap voltage reference,
featuring low power and high precision (9 ppm/°C of temperature
drift) in a tiny TSOT package.
The AD8608 is a quad version of the AD8605 and can be used
as a substitute for the AD8606, if additional precision op-amps
are needed.
The AD8601, AD8602, and AD8604 are single, dual, and quad
rail-to-rail, input and output, single-supply amplifiers featuring
very low offset voltage and wide signal bandwidth, that can be
used in place of AD8605, AD8606, and AD8608.
The AD7457 is a 12-bit, 100 kSPS, low power, SAR ADC, and
can be used in combination with the ADR391 voltage reference
in place of AD7091R, when a 300 kSPS throughput rate is not
needed.
CIRCUIT EVALUATION AND TEST
This circuit uses the EVAL-CN0336-PMDZ circuit board, the
SDP-PMD-IB1Z, and the EVAL-SDP-CB1Z system demonstration
platform (SDP) evaluation board. The interposer board SDP-
PMD-IB1Z and the SDP board EVAL-SDP-CB1Z have 120-pin
mating connectors. The interposer board and the EVAL-
CN0336-PMDZ board have 12-pin Pmod matching connectors,
allowing quick setup and evaluation of the circuit’s performance.
The EVAL-CN0336-PMDZ board contains the circuit to be
evaluated, as described in this note and the SDP evaluation
board is used with the CN0336 evaluation software to capture
the data from the EVAL-CN0336-PMDZ circuit board.
Equipment Needed
• PC with a USB port Windows® XP or Windows Vista® (32-
bit), or Windows® 7/8 (64- or 32-bit)
• EVAL-CN0336-PMDZ circuit evaluation board
• EVAL-SDP-CB1Z SDP evaluation board
• SDP-PMD-IB1Z interposer board
• CN0336 evaluation software
• Current calibrator (4 mA to 20mA current source)
Getting Started
Load the evaluation software by placing the CN0336 evaluation
software disc in the CD drive of the PC. You also can download
the most up to date copy of the evaluation software from
CN0336 evaluation software. Using My Computer, locate the
drive that contains the evaluation software disc and open the
Readme file. Follow the instructions in the readme file for
installing and using the evaluation software.
Functional Block Diagram
Figure 5 shows a functional block diagram of the test setup.
Setup
• Connect the EVAL-CFTL-6V-PWRZ (+6 V dc power
supply) to SDP-PMD-IB1Z Interposer Board via the dc
barrel jack.
• Connect the SDP-PMD-IB1Z (interposer board) to EVAL-
SDP-CB1Z SDP board via the 120-pin Con A connector.
• Connect the EVAL-SDP-CB1Z (SDP board) to the PC via
the USB cable.
• Connect the EVAL-CN0336-PMDZ evaluation board to
the SDP-PMD-IB1Z Interposer Board via the 12-pin
header Pmod connector.
• Connect the 4 mA to 20 mA current source (current
calibrator) to the EVAL-CN0336-PMDZ evaluation board
via the terminal block J2.
Test
Launch the evaluation software. The software can communicate
to the SDP board if the Analog Devices System Development
Platform drivers are listed in the Device Manager. Once USB
communications are established, the SDP board can be used to
send, receive, and capture serial data from the EVAL-CN0336-
PMDZ board. Data can be saved in the computer for various
values of input current.Information and details regarding how
to use the evaluation software for data capturing can be found
in the CN0336 Software User Guide. Information and details
on the SDP board can be found in the SDP User Guide.
A photo of the EVAL-CN0336-PMDZ evaluation board is
shown in Figure 6.
Rev. A | Page 5 of 7