Datasheet UG-181 Datasheet (ANALOG DEVICES)

PLC Demo System User Guide

A

UG-181

One Technology Way • P. O . Box 9106 • Norwood, MA 02062-9106, U.S.A. • Tel : [phone] • Fax : [phone] • www.analog.com

PLC Demo System, Industrial Process Control Demo System

FEATURES

EMC performance tested
Inputs selectable: 0 mA to 20 mA, 4 mA to 20 mA, 0 V to 5 V,

0 V to 10 V, ±5 V, ± 10 V, R TD, TC

Outputs programmable: 0 mA to 20 mA, 0 mA to 24 mA,

4 mA to 20 mA, 0 V to 5 V, 0 V to 10 V, ±5 V, ±10 V

Four isolated 24-bit analog input channels

AD7793 24-bit sigma-delta (Σ-Δ) ADC, 40 nV noise
AD8220 instrumentation amplifier, >80 dB CMRR
ADuM5401 isoPower® integrated, isolated dc-to-dc

converter, 500 mW output power

ADR441 precision 2.5 V reference

4 isolated 16-bit analog output channels

AD5422 single-channel, 16-bit, serial input, current source

and voltage output DAC

0.01% typical total unadjusted error (TUE)
Single chip solution
Output fault detection and protection

Power/interface/control

Analog Devices, Inc., ARM7 ADuC7027

ADP1715 500 mA low-dropout CMOS linear regulator

ADM3251E isolated single-channel RS-232 line

driver/receiver

APPLICATIONS

Process control
Transmitters
Actuator control
PLC/DCS systems

GENERAL DESCRIPTION

The PLC demonstration system is aimed at demonstrating the
value Analog Devices parts can add to a PLC system. The demo

board contains four fully isolated ADC channels, a micro­processor with RS-232 interface and four fully isolated DAC
output channels.

Input ranges are hardware programmable and include 0 V to
5 V, 0 V to 10 V, ±5 V, ±10 V, 4 mA to 20 mA, 0 mA to 20 mA,
±20 mA, thermocouple and RTD. Output ranges are software
programmable and include 0 V to 5 V, 0 V to 10 V, ±5 V,
±10 V, 4 mA to 20 mA, 0 mA to 20 mA, and 0 mA to 24 mA.

The PLC demo system features the AD5422 (a single-chip
16-bit DAC solution with ±0.05% TUE) and AD7793 (low
noise, low power, 24-bit Σ-Δ ADC). Isolation is achieved using
the ADuM5401 (quad-channel isolator with integrated dc-to­dc converter), ADuM1401 (quad-channel isolator), or

ADM3251E (fully isolated RS-232 transceiver).

Input signal conditioning is performed by the AD8220 (>80 dB
CMRR, JFET in-amp). Voltage references include the ADR441,

ADR445 (ultralow noise, XFET® voltage reference), and
ADP1720 (50 mA, high voltage, micropower linear regulator).

Communications with the ADC and DAC channels take place
using the ADuC7027 microcontroller, which can be connected
to a PC via an isolated RS-232 interface.

NALOG SIGNALS

SENSOR INPUTS

• RTD

• TC

• GAS

VOLTAGE INPUTS
(FLOW, PRESSURE)

• 0V TO 5V, 0V TO 10V

• ±5V, ±10V

CURRENT INPUTS
(COMMU NICATIONS)

• 0mA TO 20mA

• 4mA TO 20mA

Figure 1. PLC System Level Diagram

PLC

MODULE

BOARD

ANALOG OUTPUTS

VOLTAGE OUTPUTS

• 0V TO 5V, 0V TO 10V

• ±5V, ±10V

CURRENT OUTPUTS

• 0mA TO 20mA

• 0mA TO 24mA

• 4mA TO 20mA

09257-001

09257-002

Figure 2. PLC Demo Board

PLEASE SEE THE LAST PAGE FOR AN IMPORTANT
WARNING AND LEGAL TERMS AND CONDITIONS.

Rev. 0 | Page 1 of 16

UG-181 PLC Demo System User Guide

TABLE OF CONTENTS

Features .............................................................................................. 1

Applications ....................................................................................... 1

General Description ......................................................................... 1

Revision History ............................................................................... 2

PLC Total Solution Diagram ........................................................... 3

Demo Systems Hardware ................................................................. 4

Inputs ............................................................................................. 4

Outputs .......................................................................................... 5

REVISION HISTORY

8/10—Revision 0: Initial Version

Power Supplies ...............................................................................6

RS-232 Communications .............................................................6

Demo System Software .....................................................................7

Software Installation .....................................................................7

Software Operation .......................................................................7

Firmware .........................................................................................9

EMC Test Results ............................................................................ 10

Simplified Input/Output circuit Diagrams ................................. 11

Rev. 0 | Page 2 of 16

PLC Demo System User Guide UG-181

PLC TOTAL SOLUTION DIAGRAM

V/I INPUT S, BIPOLAR SUPPLY, HIGH PERF ORMANCE

±15V

ADR441

AD8220

V/I INPUTS, SINGLE SUPPLY, LO WER COST

IOUT1

IOUT2

ADR441

IOUT1

ADP1720

2.5V 5V

AD7793

2.5V 5V

±15V
ISOLATED
DC-TO-DC

ADuM1401

ISOLATED

ADuM5401

24V

5V

SPI

ADP1715

3.3V

5V

ISO DC-TO-DC

ADuM1401

ISOLATED

ADR445

AD5422

DAC

SPI

24V

(>30mA)

±15V
ISOLATED
DC-TO-DC

OPEN

DETECT

I

OUT

RANGE
SCALE

V

OUT

RANGE
SCALE

OVERTEMP

DETECT

4mA TO 20mA,
0mA TO 24mA

0V TO 5V,
0V TO 10V,
±5V, ±10V

AD8220

IOUT2

AD7793

TX/RX

ISOLATED

ADM3251E
ISOLATED

RS-232

5V

3.3V

ADuC7027

AD5422

ADuM1401

DAC

SPI

ISOLATED

(>30mA)

±15V
ISOLATED
DC-TO-DC

OPEN

DETECT

I

OUT

RANGE
SCALE

V

OUT

RANGE
SCALE

OVERTEMP

DETECT

4mA TO 20mA,
0mA TO 24mA

0V TO 5V,
0V TO 10V,
±5V, ±10V

09257-003

Figure 3. PLC Block Diagram

Rev. 0 | Page 3 of 16

UG-181 PLC Demo System User Guide

DEMO SYSTEMS HARDWARE

Figure 4 shows the locations of the various functional blocks of
the PLC demo system.

OUTPUT 4

INPUT 4

OUTPUT 3

Input Connectors

Each input channel contains three sets of connectors; Jx1
connectors for voltage and current inputs, Jx2 connectors for
thermocouple inputs, and Jx3 for RTD inputs (see Figure 6).
Although all the channels allow for all three input types, the
PLC demo software limits the inputs as described in Table 2.

INPUT 3

INPUT 2

INPUT 1

Figure 4. Channel Locations

OUTPUT 2

OUTPUT 1

09257-004

INPUTS

DIP switches on the PLC demo board must be set to configure
each input channel to the required input range. These switches
are found to the left of each input channel’s circuitry. Figure 5
shows a diagram of these switches, and Tab le 1 lists the required
switch configurations for each input range.

1

2

3

4

5

6

7

8

Figure 5. Input Channel Switches

Table 1. Input Channel Switch Settings

Range

Switch
No.

0 V to 5 V,
±5 V

0 V to 10 V,
±10 V

1 On Off On Off Off
2 Off Off Off Off Off
3 Off Off On Off Off
4 On On On Off Off
5 On On On Off Off
6 On On On Off Off
7 Off Off Off On Off
8 Off Off Off On Off

ON

Current

9257-005

Thermo­couple RTD

–

VOLTAGE AND CURRENT INPUTS
0V TO 5V, 0V TO 10V, ±5V, ±10V

Jx1

0mA TO 20mA, 4mA TO 20mA, ±20mA

+

–

THERMOCOUPL E INPUT

Jx2Jx3

+

I

OUT2

I

3-WIRE RTD I NPUT

OUT1

REF

Figure 6. Input Connectors

09257-006

Table 2. Ranges Allowed in PLC Demo Software

Input Channel Input Type

1 JA1—voltage and current (unipolar)
2 JB2—thermocouple
3 JC1—voltage and current (bipolar)
4 JD3—RTD

Voltage and Current

The JA1 and JC1 connectors allow for various signaling inputs
(see Figure 6). JA1 (Channel 1) allows for single-ended unipolar
inputs: 0 V to 5 V, 0 V to 10 V, 4 mA to 20 mA, and 0 mA to
20 mA. Figure 20 shows a circuit diagram of this input. JC1
(Channel 3) allows for differential inputs: 0 V to 5 V, 0 V to
10 V, ±5 V, ±10 V, 4 mA to 20 mA, 0 mA to 20 mA, and
±20 mA. Figure 21 shows a circuit diagram of this input. To
set the input range switches, see Tabl e 1.

The 250 Ω current sensing resistor on the input channels has a
25 ppm/°C drift specification. The user can observe the drift
from this resistor and can chose to replace this with a lower
drift resistor if greater performance is desired.

Rev. 0 | Page 4 of 16

PLC Demo System User Guide UG-181

Thermocouple

JB2 (Channel 2) is for thermocouple inputs (see Figure 6).
Figure 22 shows a circuit diagram of this input. The PLC
software allows the user to connect many different thermo­couple types including J-, K-, and T-types. To set the input
range switches for thermocouple inputs, see Tab l e 1.

The PLC demo system hardware comes with a T-type
thermocouple. Figure 7 shows how to connect this
thermocouple to the PLC demo board.

OUTPUTS

Each output channel contains both a current and a voltage
output connector. The relevant connectors are +VOUT/GND
and IOUT/GND (Figure 9). The available output ranges are 0 V
to 5 V, 0 V to 10 V, ±5 V, ±10 V, 4 mA to 20 mA, 0 mA to 20 mA,
and 0 mA to 24 mA. On each channel, either the voltage or
the current output can be enabled. The output that is not in
use is tristated. If neither channel is enabled both are tristated.
Figure 24 shows a circuit diagram of the output channels.

09257-007

Figure 7. Thermocouple Connector

RTD

JD3 (Channel 4) is for 3-wire RTD inputs (see Figure 6).
Figure 23 shows a circuit diagram for these inputs. To set
the input range switches for 3-wire RTD inputs, see Ta ble 1 .

The PLC demo system hardware comes with a PT1000 RTD
temperature sensor. Figure 8 shows how to connect this RTD
to the PLC demo board.

OPTIONAL 32V INPUT

TO INCREASE THE VOLTAGE

COMPLIANCE LIMIT ON THE

CURRENT OUTPUT

VOLTAGE OUTPUT

0V TO 5V,

0V TO 10V,

±5V, ±10V

CURRENT OUTPUT

0mA TO 20mA,
4mA TO 20mA,

0mA TO 24mA

+32VDC

GND

+VOUT

GND

IOUT

GND

09257-009

Figure 9. Output Connectors

Increasing the Output Compliance

The voltage compliance limit on the current output is 12.5 V.
A connector is available to externally provide 32 V dc, which
increases the output compliance to 29.5 V. The relevant
connectors are labeled +32VDC and GND (see Figure 9).
Figure 10 shows how +32VDC is connected to the channel
supply of the AD5422. There is a 20 V TVS on the I

, which

OUT

may need to be changed/removed if an external supply is used.

+15V

ISO

+32VDC

GND

Figure 8. RTD Connection

–15V

ISO

V

V

DD

SS

V

I

OUT

OUT

I

OUT

GND

09257-010

AD5422

Figure 10. +32VDC Connection on the Output Channels

09257-008

Rev. 0 | Page 5 of 16

UG-181 PLC Demo System User Guide

POWER SUPPLIES RS-232 COMMUNICATIONS

The PLC demo system uses an RS-232 straight through DB-9
connector. This connector is supplied with the PLC demo
system board. The RS-232 signal can be connected straight to
the RS-232 port of the PC. If the PC being used does not have
an RS-232 port, a RS-232-to-USB converter can be used.

COM

+24VDC

09257-011

Figure 11. Power Connections

The demo board should be powered by a 24 V dc, ±10%,
500 mA supply. This should be connected via the +24VDC
INPUT (JP2) socket. All other supplies on the PLC demo
board are derived from this 24 V dc supply.

The RS-232 connection between the PLC demo board and PC
is fully isolated using the ADM3251E isolated single-channel
RS-232 line driver/receiver.

Rev. 0 | Page 6 of 16

PLC Demo System User Guide UG-181

DEMO SYSTEM SOFTWARE

SOFTWARE INSTALLATION

The demonstration kit includes self-installing software. The
software is compatible with Windows® 2000 and Windows XP.
Run the setup.exe file to begin the installation.

After the installation has completed, connect the demo board
to the computer serial port using a serial cable and power the
board using a 24 V dc supply as described in the Power Supplies
section.

SOFTWARE OPERATION

1. To run the software, click Start > All Programs > Analog

Devices > PLC Demo System > PLC EVALUATION SW
V3.x. The window in Figure 12 should appear.

09257-013

Figure 13. Menu Bar

The following tabs are available in the software:

• Operate tab

• Thermocouple tab

• PT1000 RTD tab

• ADC Stats tab

• ADC Configure tab

• DAC Configure tab

Figure 12. Main Window

2. The menu bar on the left of the main window (see

Figure 13) allows the user to select the ADC/DAC
channel and range. It also allows the user to set the
RS-232 communication port of the PC.

To set up an input channel, see the Demo Systems
Hardware section. Ensure the ADC range switches
are set correctly for the selected channel.

Then, use the correct connector for the specified

channel

and range.

Operate Tab

09257-012

The Operate tab can be used with Input Channel 1 and Input
Channel 3 as well as all the output channels. In the Operate tab
of the software window, you can

• Perform an ADC conversion(s).

• Write to an output channel. To do this, enter a value in

the DAC Output Value box and click Write. The hex
value written to the DAC is displayed to the right of
these controls.

09257-014

Figure 14. Operate Tab

Rev. 0 | Page 7 of 16

UG-181 PLC Demo System User Guide

Thermocouple Tab

The Thermocouple tab allows for thermocouple measurement
on Output Channel 2. See the Demo Systems Hardware section
for setting up a thermocouple channel. Click Run to start the
measurement (see Figure 15).

The measurement is performed by executing a thermocouple
voltage reading (the bias voltage generator for the AD7793 is
used for this) followed by a cold-junction reading from the
on-board thermistor (using the excitation current sources
of the AD7793).

See the AN-880 Application Note, ADC Requirements for
Temperature Measurement Systems, for information on
thermocouple measurements using the AD7793.

ADC Stats Tab

The ADC Stats tab can be used to perform statistical analysis
on channel input. To carry out this analysis, complete the
following steps:

1. Connect the input channel to the desired source.

2. Select the number of samples to be taken from the No.

of Samples box.

3. Click Measure.

4. The sampling can be stopped at any stage by clicking

STOP.
Once the sampling is complete, the histogram is updated
as well as the statistical information (mean, RMS value,
p-p noise, standard deviation, and p-p resolution)

09257-015

Figure 15. Thermocouple Tab

PT1000 RTD Tab

The PT1000 RTD tab allows for RTD measurement on ADC
Channel 4. See the Demo Systems Hardware section for setting
up an RTD channel. Click Run to start the measurement (see
Figure 16).

See the AN-880 Application Note, ADC Requirements for
Temperature Measurement Systems, and the AD7793 data
sheet, for information on RTD measurements using the
AD7793.

09257-025

Figure 16. PT1000 RTD Tab

Figure 17. ADC Stats Tab

9257-016

Rev. 0 | Page 8 of 16

PLC Demo System User Guide UG-181

ADC Configure Tab DAC Configure Tab

Use the ADC Configure tab to alter ADC register settings.
Some of these setting are automatically altered when using
the Thermocouple or PT1000 RTD tab (see Figure 18).

The ADC Configure tab also displays the current calibration
values. The ADC can be recalibrated using the following
procedure:

1. Connect a (precision) dc source to the system voltage

input (Jx3 connector).

2. Ensure that the correct input range is set in both the

hardware and the software.

3. Click New Calibration and follow the on-screen

instructions.

Use the DAC Configure tab to alter the control register of a
DAC (see Figure 19).

To revert to the default calibration values, click Load Original
Values. These default calibration values were created using the
DAC outputs. To generate more accurate calibration values,
use a precision dc source as previously outlined in this section.

09257-017

Figure 18. ADC Configure Tab

09257-019

Figure 19. DAC Configure Tab

FIRMWARE

The firmware on the ADuC7027 is designed to perform basic
communications between the on-board data converters and a
PC. This basic firmware is available on the PLC website. The
firmware that comes on the PLC demo board also has functions
to store calibration data for the PLC demo software.

Rev. 0 | Page 9 of 16

UG-181 PLC Demo System User Guide

EMC TEST RESULTS

A sample was tested during initial release and met the following test compliances. These results should be viewed as typical data taken at
25°C. For these tests, the DAC outputs were connected to the DAC inputs, that is, DAC2 to ADC2, DAC3 to ADC3, and DAC4 to ADC4.
The DAC outputs were set to 5 V, 6 V, and 10 mA, respectively.

Table 3.

Test Item Description Result

EN55022

EN and IEC 61000-4-2

EN and IEC 61000-4-3

EN and IEC 61000-4-4

EN and IEC 61000-4-5 Power line surge, ±2 kV

EN and IEC 61000-4-6

Radiated emission Class A,
3-meter anechoic chamber

Electrostatic discharge (ESD)
±8 kV VCD

Electrostatic discharge (ESD)
±8 kV HCD

Radiated immunity 80 MHz to
1 GHz 18 V/m, vertical antenna
polarization

Radiated immunity 80 MHz to
1 GHz 18 V/m, horizontal antenna
polarization

Electrically fast transient (EFT)
±4 kV power port

Electrically fast transient (EFT)
±2 kV analog I/O ports

Conducted immunity test on
power cord, 10 V/m for 30 minutes

Conducted immunity test on I/O
cable 10 V/m for 30 minutes

Passed and met −6 dB margin.

Maximum deviations in Input Channel 2, Input Channel 3, and Input Channel 4
are respectively −8 ppm, 10 ppm, 13 ppm when there is interference.

Maximum deviations in Input Channel 2, Input Channel 3, and Input Channel 4
are respectively −8 ppm, 10 ppm, 13 ppm when there is interference.

Maximum deviations in Input Channel 2, Input Channel 3, and Input Channel 4
are 0.05%, 0.004%, −0.13%. Performance automatically resorted to ≤0.05%
after interference. Class B.

Maximum deviations in Input Channel 2, Input Channel 3, and Input Channel 4
are −0.09%, 0.003%, −0.02%. Performance automatically resorted to ≤0.05%
after interference. Class B.

Passed Class B.

Passed Class B

No board or part damage occurred, no performance degrade, passed with
Class A.

Maximum deviations in Input Channel 2, Input Channel 3, and Input Channel 4
are respectively 9.3%, 11%, 3.4%. Passed Class B.

Maximum deviations in Input Channel 2, Input Channel 3, and Input Channel 4
are respectively 4.5%, 4.7%, 1.4%. Performance automatically resorted to
≤0.05% when interference stopped.

Rev. 0 | Page 10 of 16

PLC Demo System User Guide UG-181

V

SIMPLIFIED INPUT/OUTPUT CIRCUIT DIAGRAMS

Figure 20 shows a simplified circuit diagram for Input Channel 1
(Input Channel 2 follows the same format). On the input side,
the precision current setting resistor can be switched in and out
selecting either current or voltage mode. Resistors R

and RB

A

divide down the input signal into the range of the AD7793.
The AD8226 output is biased with a common-mode signal
connected to the REF pin so that the signal meets the input
requirements of the AD7793.

For more information on this circuit, see Circuit Note CN-0067.

FERRITE BEAD

250Ω
LOW DRIFT

TVS

RESIST OR

20V

INPUT

S3

ISO

R

A

51kΩ

R

B

S1

REF

AD8226

R

G

R

G

ISO

S4

S5

AIN1(+)

AIN1(–)

Figure 21 shows a simplified circuit diagram for Input Channel 3
(Input Channel 4 follows the same format). On the input side,
the precision current setting resistor can be switched in and out
selecting either current or voltage mode. Resistors R
divide down the pseudodifferential input signal into the range
of the AD7793. The AD8226 output is biased with a common­mode signal connected to the REF pin so that the signal meets
the input requirements of the AD7793. This circuit has bipolar
supplies and, thus, allows bipolar inputs.

For more information on a similar circuit, see Circuit Note

CN-0067.

ADuM5401

AV

DD

AD7793

REFIN( +) REFI N(–)

ISO ISO

S6

CS

SCLK

DIN

DOUT

GND

ISO

ISO

V

ISO

GND

V

OA

V

OB

V

OC

V

ID

V

SEL

GND

ISO

ISO

V

GND1

RC

GND1

V

DD1

V

V

V

OD

OUT

5V

IA

IB

IC

CS

SCLK

D

D

OUT

GND

IN

and RB

A

EXTERNAL INPUTS

AD8601

0.5V

ISO

25kΩ

5.1kΩ

ISO

ADR441

V

OUTVIN

ISO

09257-020

Figure 20. Input Channel 1 and Input Channel 2—Voltage and Current Input

+15

ISO

ISOLATED

BIPOLAR

SUPPLY

+15V

ISO

ADR441

ISO

ISO

ADuM1401

V

DD2

GND

V

OA

V

OB

V

OC

V

ID

V

E2

GND

OUTVIN

+15V

REF

R

R

G

G

ISO

AD8226

+15V

ISO

ISO

AV

AIN1(+)

S4

AIN1(–)

S5

DD

AD7793

REFIN(+) REFIN(–)

ISO ISO

S6

CS

SCLK

DIN

DOUT

GND

FERRITE BEAD

250Ω
LOW DRIFT

TVS

RESISTO R

20V

INPUT

S3

FERRITE BEAD

ISO

R

A

51kΩ

R

B

R

B

S1

R

A

ADR441

V

OUTVIN

ISO

Figure 21. Input Channel 3 and Input Channel 4—Voltage and Current Input

ISO

–15V

ISO

V

DD1

GND

V

GND

1

V

IA

V

IB

V

IC

OD

V

E1

1

2

2

5V

CS

SCLK

D

D

OUT

GND

IN

EXTERNAL INPUTS

09257-021

Rev. 0 | Page 11 of 16

UG-181 PLC Demo System User Guide

A

T

A

Figure 22 shows a simplified circuit diagram for the thermo­couple inputs. The ADC includes an on-chip PGA and can,
therefore, accept small signal inputs from sensors directly. The
PGA gains can be set for 1, 2, 4, 8, 16, 32, 64, or 128. The PLC
demo board also includes an on-board thermistor for the cold­junction compensation measurement.

See the AN-880 Application Note, ADC Requirements for
Temperature Measurement Systems, and the AD7793 data
sheet for information on thermocouple measurements using
the AD7793.

IOUT2

HERMISTOR

5.1kΩ

LOW DRIFT

RESISTOR

THERMOCOUPL E

INPUT

S8

S7

ISO

AIN2(+)

AIN2(–)

AIN1(+)

AIN1(–)

IOUT1

V

BIAS

Figure 23 shows a simplified circuit diagram for the 3-wire RTD
inputs. The AD7793 contains two matched excitation current
sources for 3-wire RTD measurements. See the AN-880 Appli­cation Note, ADC Requirements for Temperature Measurement
Systems, and the AD7793 data sheet, for information on RTD
measurements using the AD7793.

DuM5401

AV

IN­AMP

REFIN(+)

DD

AD7793

Σ-Δ

ADC

REFIN(–)

ISO

SCLK

DOUT

ISO

CS

DIN

GND

ISO

ISO

V

ISO

GND

V

OA

V

OB

V

OC

V

ID

V

SEL

GND

ISO

ISO

V

GND1

RC

GND1

DD1

V

V

V

V

OUT

5V

IA

IB

IC

OD

CS

SCLK

D

D

OUT

GND

IN

EXTERNAL INPUTS

ISO

09257-022

Figure 22. Thermocouple Inputs

DuM5401

INPUT

3-WIRE RTD

5.1kΩ

LOW DRIFT

RESISTOR

ISO

ISO

AIN2(+)

AIN2(–)

AIN1(+)

AIN1(–)

IOUT2

IOUT1

AV

DD

AD7793

REFIN(+)

REFIN(–)

SCLK

DOUT

ISO

CS

DIN

GND

ISO

ISO

V

ISO

GND

V

OA

V

OB

V

OC

V

ID

V

SEL

GND

ISO

ISO

V

GND1

RC

GND1

V

DD1

V

V

V

OD

OUT

5V

IA

IB

IC

CS

SCLK

D

D

OUT

GND

IN

EXTERNAL INPUTS

09257-023

Figure 23. 3-Wire RTD Inputs

Rev. 0 | Page 12 of 16

PLC Demo System User Guide UG-181

V

Figure 24 shows a simplified circuit diagram for Output
Channel 3 and Output Channel 4. Output Channel 1 and
Output Channel 2 are the same except they use the AD5422
internal 10 ppm/°C (maximum) reference. An internal boost
transistor is available on-chip though an external boost

+15

ISO

ADR445

VINV

+15V

ISO

OUT

–15V

ISO

ISOLATED

BI-POLAR

SUPPLY

+15V

–15V

ISO

ISO

ISO

ADuM1401

AV

AV

DD

ISO

SS

CLEAR

SELECT

LOW DRIF T

RESISTOR

EXTERNAL INPUTS

3.3V

SYNC

SCLK

DIN

0V

V

DD1

GND

V

IA

V

IB

V

IC

V

OD

V

E1

GND

V

DD2

GND

V

V

V

GND

2

OA

OB

OC

V

ID

V

E2

2

1

1

ISO

DV

CC

LATCH

SCLK

SDIN

SDO

FAU LT

CLEAR GND

Figure 24. Output Channel 3 and Output Channel 4—Voltage and Current Output

REFIN

AD5422

R

15kΩ

transistor has been used for those who may wish to operate
at the extremes of the supply voltage, load current, and
temperature range.

For more information on this circuit, see Circuit Note CN-0065.

SET

BOOST

ISO

–V

C

SENSE

COMP

4nF

ISO

+15V

C

B

E

1kΩ 10Ω

22nF

ISO

ISO

FERRITE

ISO

+15V

I

OUT

+V

SENSE

V

OUT

BEAD

TVS

20V

ISO

–15V

ISO

–15V

ISO

TVS
20V

ISO

CURRENT
OUTPUT

RL

VOLTAGE
OUTPUT

09257-024

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UG-181 PLC Demo System User Guide

NOTES

Rev. 0 | Page 14 of 16

PLC Demo System User Guide UG-181

NOTES

Rev. 0 | Page 15 of 16

UG-181 PLC Demo System User Guide

NOTES

ESD Caution
ESD (electrostatic discharge) sensitive device. Charged devices and circuit boards can discharge without detection. Although this product features patented or proprietary protection

circuitry, damage may occur on devices subjected to high energy ESD. Therefore, proper ESD precautions should be taken to avoid performance degradation or loss of functionality.

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UG09257-0-8/10(0)

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