The industrial control market involves the monitoring and control aspects of both complex and simple processes. Common trends within the industry, notably the drive for increased efficiencies, better robustness, higher channel densities, and faster monitoring and control speeds, subsequently drive new technology advancements for semiconductor manufacturers. This session aims to give a broad overview into the system requirements for both field instruments (sensors/actuators) and control room (analog input/output) modules, and demonstrates a typical I/O module configuration with HART (highway addressable remote transducer) connectivity.

1. Process Control
Reference Designs and System Applications

2. Legal Disclaimer
 Notice of proprietary information, Disclaimers and Exclusions Of Warranties
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©2013 Analog Devices, Inc. All rights reserved.
2

3. Today’s Agenda
Field Instruments
 Introduction
 2-wire/4-wire systems—loop-powered vs. non loop-powered
 Communications
PLC/DCS Systems
 Introduction
 Analog input module
 Analog output module
Demo Update
 Circuits from the Lab® reference circuits
3

4. Industrial Field Instruments
4
Introduction

5. Industrial Control System
5
Sensing
Control Data/
Communication
Control
Process
Visualization
Field
Control Room
Field
Instruments
Actuators PLC
Control

6. High Level System Level Overview
Typical Sensor Actuator Network Architecture
 Control network options: industrial Ethernet, field buses, RS-485, CAN, …
 Field network options: 4 mA to 20 mA, HART®, IO-link, AS-interface, CC-
link/LT, CompoNet, RS-485, …
 Sensors and actuators available, which support field level and control level
connectivity
6

7. Industrial Field Instruments
7
Field Instrument

8. Field Instrument—Sensors
Temperature
Pressure
Flow
Level
Position
Angle
Acidity (pH)
Oxygen Content
Gas Detection
Corrosion
8

9. Two Categories of Transmitters
Loop-Powered
 2-wire connection supplying both power and communication
 Power is supplied over the current loop from the control room
 Entire transmitter must operate on <3.2 mA for a standard transmitter and
<2.7 mA for a HART enabled transmitter
Non Loop-Powered
 4-wire connection, two for power and two for communication
 No power consumption limitations
 Used in situations where sufficient power cannot be derived from the
current loop
9

10. 2-Wire Connection, 4 mA to 20 mA Loop
Current Loop Carries Both:
 Information
 AND
 Power for Instrument
Only Low Power Available
 Min voltage for instrument
 Usually specified as ≥12 V
 Min current
 ≤4 mA
 Total available power <50 mW
Low Power Design
10
ADC
Rsens
~250 Ω
4–20mA
ANALOG
INPUT
CONTROL
SYSTEM
FIELD
INSTRUMENT
24V DC.
POWER SUPPLY
2-WIRE CONNECTION

11. Field Instrument Signal Chain
Loop-Powered Pressure Transmitter
11
Σ−∆
ADC
MUX
DIFFERENTIAL
PRESSURE (MAIN
VALUE MEASURED)
STATIC PRESSURE
(COMPENSATION)
TEMPERATURE
(COMPENSATION)
Σ−∆
ADC
MCU
FLASH
SRAM
CALIBRATION
LINEARIZATION
COMPENSATION
IN-AMP
(PGA)
ADC
(24-BIT)
IN-AMP
(PGA)
ADC
(24-BIT)
CLOCK
DAC
(16-BIT)
4mA to 20mA
DRIVER
DAC
COMMUNICATION
POWER MANAGEMENT
VREF
LCD
WATCHDOG
HART
MODEM
4-20 mA
+HART
VOLTAGE
REGULATORS
(SPI)
(UART)
(I2C)DIAGNOSTICS
PROCESSING
32-BIT RISC

12. Loop-Powered System Architecture
Modem
ADC MCU
3.3V
FET
LOOP IN
LOOP OUT
10 V to 45 V supply
4 mA to 20 mA
DAC
LDO
R1 R2
Total Energy Available Under Worst Case 3.3 V at 4 mA
Circuit regulates current
as appropriate via sense resistor
Current is modulated
to deliver more or less
current from FET as
needed
I
The total system must run from <4 mA.
This includes sensor/ADC/MCU/4 mA to 20 mA
circuitry power.
→ Every parts needs to be as low power
as possible..
12

13. Key Trends to Field Instruments
The Housing is Becoming
Smaller
 Need for smaller parts
 Need for more integration
 Need for higher temp rated
parts
 Need for more efficient parts
 More safety targeted parts—
diagnostics
There Is a Trend for More
Processing Requirements
 Lower power MCU cores
 Better processing capability
13

14. Pressure Transmitter
(Loop-Powered Instrument)
Industrial Field Instruments
14

15. Field Instrument Signal Chain
Loop-Powered Pressure Transmitter
15
Σ−∆
ADC
MUX
DIFFERENTIAL
PRESSURE
(MAIN VALUE MEASURED)
STATIC
PRESSURE
(COMPENSATION)
TEMPERATURE
(COMPENSATION)
Σ−∆
ADC
MCU
FLASH
SRAM
CALIBRATION
LINEARIZATION
COMPENSATION
IN-AMP
(PGA)
ADC
(24-BIT)
IN-AMP
(PGA)
ADC
(24-BIT)
CLOCK
DAC
(16-BIT)
4 mA to 20 mA
DRIVER
DAC
COMMUNICATION
POWER MANAGEMENT
VREF
LCD
WATCHDOG
HART
MODEM
4-20 mA
+HART
VOLTAGE
REGULATORS
(SPI)
(UART)
(I2C)DIAGNOSTICS
PROCESSING
32-BIT RISC

16. Field Instruments—Analog Front End
ADI SUCCESS: AD779x Family
16
Σ−∆
ADC
MUXDifferential Pressure
(Main Value Measured)
Static Pressure
(Compensation)
Temperature
(Compensation)
Σ−∆
ADC
uC
CALIBRATION
LINEARIZATION
COMPENZATION
In-AMP
(PGA)
ADC
(24-bit)
DIAGNOSTICS
In-AMP
(PGA)
ADC
(24-bit)
uC
COMMUNICATION
HART
MODEM
DAC
(16-bit)
4-20mA
Driver
DAC
LINEAR
REGULATOR
Intrinsic Safety
LINEAR
REGULATORS
12V..50V
4-20mA
POWER
MANAGEMENT
VREF
uC
DISPLAY
LCD
SWITCH MODE
REGULATOR
>90% efficiency
WATCHDOGS
ADI’s Success:
Low Power Sigma-Delta Cores
Fully Integrated System on a Chip

17. Application—Thermocouple Sensor
 Application Features
 Cold-Junction Compensation
 Thermocouple voltage is proportional to
the temperature difference
 Second sensor needed to measure
temperature of the “cold junction”
 Low Voltage Signal
 −20 mV to +80 mV FS
 10 µV/°C to 50 µV/°C
 Long Connections
 50 Hz/60 Hz interference
 Front-End Solution with 16- to 24-Bit
Σ-Δ ADC
 AD7792/AD7793—low power, in-amp, voltage
reference, excitation currents, 50 Hz/60 Hz rejection
 AD7708/AD7718—up to 10 AIN channels, gain, 50 Hz/60 Hz rejection
 AD7719—2 × ADC, gain, excitation currents,50 Hz/60 Hz rejection
19
VOLTAGE
REF.
ADC
FRONT - END
SERIAL
INTERFACE
CALIBRATIONS
DIAGNOSTICS
DIGITAL
FILTER
BIAS
VOLTAGE
AIN1
AIN2
IEXC
MUX
CLOCK
REFIN
RREF
RT
METAL 1
METAL 2
THERMOCOUPLE
TERMINAL
BLOCK
“COLD
JUNCTION”
Thermocouple
V ~ (T1-T2)
Programmable
Gain Amplifier
> 16-bit
Resolution
Voltage Reference for
Thermocouple Voltage
Serial
Interface
50 /60Hz
Rejection
Thermistor
or RTD
or Diode
to measure T2
Excitation
Current
AIN2 and REFIN
to measure RT / RREF
Bias
Voltage

18. Precision Analog Microcontroller
Industrial Field Instruments
20

19. Field Instrument—Example
Precision Microconverter
21
Σ−∆
ADC
MUX
DIFFERENTIAL
PRESSURE
(MAIN VALUE
MEASURED)
STATIC
PRESSURE
(COMPENSATION)
TEMPERATURE
(COMPENSATION)
Σ−∆
ADC
MCU
FLASH
SRAM
CALIBRATION
LINEARIZATION
COMPENSATION
In-AMP
(PGA)
ADC
(24-BIT)
IN-AMP
(PGA)
ADC
(24-BIT)
CLOCK
DAC
(16-BIT)
4mA to 20mA
Driver
DAC
COMMUNICATION
POWER MANAGEMENT
VREF
LCD
WATCHDOG
HART
MODEM
4-20 mA
+HART
PROCESSING
32-BIT RISC
VOLTAGE
REGULATORS
(SPI)
(UART)
(I2C)DIAGNOSTICS
MUX
ADuCM360

20. ADuCM360 Product Description
22

21. IDD:
 Cortex™-M3/SRAM/FLASH = 290 µA/MHz
 ADC – 70 µA per ADC
 PGA G = 4/8/16 = 130 µA
 PGA G = 32/64/128 = 180 µA
 DAC = 50 µA
 CPU = 500 kHz, both ADCs active, both PGAs =16, IDD = 1 mA (max)
Analog Performance:
 ADCs are 24-bit monotonic up to 500 SPS
 ADC ENOB > 21 RMS bits, fADC = 4 Hz
 ADC ENOB > 19 RMS bits, fADC = 50 Hz
 Simultaneous 50 Hz/60 Hz rejection at fADC=50 SPS, 80 dB
 Internal 1.2 V reference, Tempco = 4 ppm typ/15 ppm max
 DAC 12-bit monotonic
Other Details
 Specified for 1.8 V to 3.6 V operation (3.96 V compatible I/O)
 Packages: 7 mm × 7 mm, 48-LFCSP (complete system on a chip)
ADuCM36x Key Performance Specs—Low Power
High Performance Analog Front End
23

22. Complete Closed-Loop Precision Analog
Microcontroller Thermocouple Measurement
System With 4 mA to 20 mA Output (CN0300)
Description and Benefits:
 4 mA to 20 mA loop is the standard
interface for communicating
measured values from sensors to a
controller
 The ADuCM360, along with the
ADP1720 LDO, provides a complete
solution for loop-powered transmitter
applications
 Improve the overall system reliability
and efficiency
Inputs:
 4 mA to 20 mA loop
 Thermocouple
 RTD
End Market
Target
Applications
Key Parts
Used
• Industrial
• Field
instruments
• ADuCM360 Available now
24

23. 4-20mA Interface
Industrial Field Instruments
25

24. Field Instrument Example—
4 mA to20 mA Outputs
26
Σ−∆
ADC
MUX
DIFFERENTIAL
PRESSURE
(MAIN VALUE
MEASURED)
STATIC
PRESSURE
(COMPENSATION)
TEMPERATURE
(COMPENSATION)
Σ−∆
ADC
MCU
FLASH
SRAM
CALIBRATION
LINEARIZATION
COMPENSATION
IN-AMP
(PGA)
ADC
(24-BIT)
IN-AMP
(PGA)
ADC
(24-BIT)
CLOCK
DAC
(16-BIT)
4mA to 20mA
Driver
DAC
COMMUNICATION
POWER MANAGEMENT
VREF
RS485
WATCHDOG
HART
MODEM
4-20 mA
+HART
PROCESSING
32-BIT RISC
VOLTAGE
REGULATORS
(SPI)
(UART)
(I2C)DIAGNOSTICS
MUX
AD5421/22

25. AD5421—Integration, Accuracy, Performance,
Safety
27

26. AD5421 Enhanced Diagnostic Features
AD5421 Fault Detect Features
 SPI interface watchdog timer
 SPI interface packet error check
 Loop current out of range
 Overtemperature
 Power supply monitor
29

27. HART Communication
Industrial Field Instruments
30

28. Field Instrument Example—
4 mA to 20 mA Outputs
31
Σ−∆
ADC
MUX
DIFFERENTIAL
PRESSURE
(MAIN VALUE
MEASURED)
STATIC
PRESSURE
(COMPENSATION)
TEMPERATURE
(COMPENSATION)
Σ−∆
ADC
MCU
FLASH
SRAM
CALIBRATION
LINEARIZATION
COMPENSATION
IN-AMP
(PGA)
ADC
(24-BIT)
IN-AMP
(PGA)
ADC
(24-BIT)
CLOCK
DAC
(16-BIT)
4mA to 20mA
Driver
DAC
COMMUNICATION
POWER MANAGEMENT
VREF
LCD
WATCHDOG
HART
MODEM
4-20 mA
+HART
PROCESSING
32-BIT RISC
VOLTAGE
REGULATORS
(SPI)
(UART)
(I2C)DIAGNOSTICS
MUX
AD5700

29. What Is HART—Highway Addressable Remote
Transducer
Global
Communication
Standard
Enhances
Measurement
Capability
Enables
Diagnostics
Control SystemField Instruments
HART DIGITAL DATA
HART-
ENABLED
INSTRUMENTS
HART-
ENABLED
I/O
MODULES
ANALOG 4 mA TO 20 mA
32

30. Why HART
Industry Trends:
 Need for more diagnostics
 Need for asset management
 Need for more communication
Traditional Analog 4 mA to 20 mA
Interface…
 Single direction only
 Single channel—single value only
 Limited diagnostics—working/failing
 Limiting the system evolution
HART
 “Digital” communication option
 Analog 4 mA to 20 mA compatible
 Widely accepted, often implemented by
field instruments vendors
 Recently, wider adoption by PLC/DCS
vendors
 One of the trends in the process control
33
SENSOR
24 V DC
2-wire connection
4–20 mA DC
HART AC

31. AD5700 Integrated HART FSK Modem
Simplifying Applications, Saving PCB Space
Integrated Receive
Band-Pass Filter
Integrated Low Power
0.5% Precision Oscillator
High Output
Drive Capability
34
Minimum External Components Required

32. AD5700: Lowest Power, Smallest Package
Outperforming Existing HART Modems on
Specifications That Matter
Industry-Leading
Specifications
 Lowest power
consumption
 178 µA demodulation
and reference
 Smallest package
 24-lead, 4 mm × 4 mm
LFCSP
 Industry’s widest
temperature range
 –40°C to +125°C
 Widest supply range
 VDD of 1.71 V to 5.5 V
38%
Reduction
in Power
75%
Footprint
Savings
60%
Reduction in
External
Components
35

33. Loop-Powered System Architecture—Example
 Total Energy Available Under Worst Case 3.3 V at 3.5 mA
Modem
MCU
10 V to 45 V Supply
4 mA to 20 mA
DAC
SENSOR
Total Current ~2.722 mA
Sensors Current
Resistive Pressure
Sensor/RTD Temp
Sensor ~0.8 mA
3.3v
ADC
Cortex-M3 System on a Chip
2 x 24-Bit ADC Fully Running with Input Buffers
2 x Instrumentation Amplifier 2 (Gain = 16), Fully
Running
SPI, UART, Timers, Watchdog, Other Circuitry
Voltage Reference, RTD Current Source Reference
µC Core, FLASH, SRAM (Core Clock = 2 MHz)
Clock Generator
Total 1.72 mA
Hart Modem
Current
0.157 mA
36
FET
R1 R2
3.3V
LDO
LOOP IN
LOOP OUT
4 mA to 20 mA Output
Stage Current
4 mA to 20 mA Output
Circuitry, Including
LDO ~0.225 mA

34. Field Instrument Demo
37
HART MODEM
50Ω
DAC
LOOP(–)CIN
HART_OUT
ADC_IN
3.3V
COM
3.3V
DEMO – AD5700D2Z
AD5421ADuCM360
+
–
UART REGIN
SPI
COM
AD5700
ADC
V-REGULATOR
VLOOP
ADC 1
Temperature
Sensor
PT100
TEMP.SENSOR
REF
Vdd
Vdd
ADC 0 μC
SRAM
FLASH
Clock
Reset
Watchdog
Iexc
COM
Watchdog
Timer
3.3VPressure
Sensor
Resistive
Bridge
4-20 mA
+HART
REGOUT

35. HART Physical Layer Specification Noise
During Silence—System Design Challenging
39

36. Analog Rate of Change—Fastest Analog
Signal Settling
 Request for analog signaling step
change
 e.g., 4 mA to 20 mA
 HW filter combined with SW
algorithm
 Change split into
 20 steps in 1 ms distance
 Simple integer calculation in each
step
 1× multiplication
 1× bit manipulation
 1× integer addition
 Indexed table
 Write_DAC (DAC_previous + (DAC_diff ×
StepTable[i]) >> 16);
 Analog signal settled in ~25 ms
40
LIMIT
LIMIT

37. DEMO-AD5700-D2Z—Complete ADI Solution for
Industrial HART Communication
AD5700
HART
Modem
SPIADC
UART
AIN(+)
AIN(–)
3.3V
DAC
LOOP(–)CIN
V-REG
HART OUT
HART IN
3.3V
COM
3.3V
AD5421ADuCM360
uC
CHART
CSLEW
+
–
UART
REGIN
0-100%
SPI
REGOUT
Analog
Input
Simulation
CFILTER
41

38. HART Stack
ADI does not provide HART stack
 Plan to publish simplified example code for the demo
 ADuCM360 (configuration, PGA, 2× ADC, Vref, … )
 AD5421 (SPI)
 AD5700 (UART)
 One HART command
 But not HART stack…
HCF does not provide HART stack on commercial basis
Some 3rd parties may provide this service
42

39. Communications
Industrial Field Instruments
43

40. Field Instrument Example—
4 mA to 20 mA Outputs
44
4-20 mA
+HART
Σ−∆
ADC
MUX
DIFFERENTIAL PRESSURE
(MAIN VALUE MEASURED)
STATIC PRESSURE
(COMPENSATION)
TEMPERATURE
(COMPENSATION)
Σ−∆
ADC
MCU
FLASH
SRAM
CALIBRATION
LINEARIZATION
COMPENZATION
IN-AMP
(PGA)
ADC
(24-BIT)
IN-AMP
(PGA)
ADC
(24-BIT)
CLOCK
DAC
(16-BIT)
4mA to 20mA
DRIVER
DAC
COMMUNICATION
POWER MANAGEMENT
VREF
RS485
WATCHDOG
HART
MODEM
PROCESSING
32-bit RISC
VOLTAGE
REGULATORS
(SPI)
(UART)
(I2C)DIAGNOSTICS
MUX
PROFIBUS
CANBUS
MODBUS

41. iCoupler® and isoPower®
Isolation Products
®
45

42. Growth through Continuous Innovation and
Industry Firsts
46
®
ADuM1100
First
iCoupler
Digital
Isolator
ADuM140x
4 Channels in
1 Package
ADM248x
RS-485
ADuM120x
2 Channels
in Narrow
SO-8
AD7400
Ʃ-Δ ADC
ADuM125x
I2C
ADuM1220
½ Bridge
Gate Driver
ADuM240x
5 kV RMS
Isolation
ADuM524x
isoPower
ADuM5230
½ Bridge
Driver with
isoPower
ADM3251E
RS-232
ADuM7410
1 kV rms
ADuM4160
USB
ADM2582
RS-485 with
isoPower
ADM305x
CumulativeChannelsofiCouplerIsolation[Millions]
ADE7913
Isolated
Metering AFE
ADuM347x
Switching
Regulator

43. CANOpen Node
Customer Pain
Complexity of Solution
Size of Solution
Cost of Solution
Reliability of Solution
(Optocoupler Wearout)
Robustness
47

44. ADM3053 Applications Diagram
48

45. PLC/DCS Systems
Programmable Logic Controllers
50

46. Industrial Control System
51
Sensing
Control Data/
Communication
Control
Process
Visualization
Field
Control Room
Field
Instruments
Actuators PLC
Control

47. Market Trends—Smaller/Faster
Modules/Increased Channel Density
Intelligent Integration
Smaller form factor
More channels in same area
Intelligent Power Mgmt
Smaller housing = heat
Integrated power control
52
Channel 4
Channel 3
Channel 2
Channel 1Channel 1
Analog O/P Analog I/P
Channel 1
Channel 2
Channel 3
Channel 4
Analog I/PAnalog O/P
Channel 1
Channel 2
Channel 3
Channel 4
Channel 2
Channel 3
Channel 4
Self-Heating Issue
Lower Power Designs

48. Programmable Logic Controllers
53
Analog Outputs
Integration
Power Efficiency
Performance

49. Trends to System Requirements…
Module Size Getting Smaller → Business Card Sizes
 Power dissipated per module reduced: was 5 W to 10 W, now 3 W to 5 W,
future 2 W to 3 W
Channel Density Increasing → 8/12/16 Channels
 Increases power dissipation
Increased Speed (Settling) for Factory Automation
 Down to 20 µS for analog output channels → still require efficiency
Increased Safety Requirements for Process (SIL)
 Increased diagnostics/robustness
50

50. Innovation Evolution for Industrial Outputs
55
 First Quad Universal Output Solution
 First Integrated Dynamic Power Control
 Integrated Functions and Diagnostics
 Fully Programmable Outputs
OP2177
OP2177
OP2177
OP2177
AD5664
Discrete Solution
Quad DAC + Ext Gain Amps
Vout
Iout
AD5750
Vout
Iout
AD5750
Vout
Iout
AD5750
Vout
Iout
AD5750
AD5664
Semi-Integrated Solution
Quad DAC + 4 Ext Drivers
Vout
Iout
AD5422
Vout
Iout
AD5422
Vout
Iout
AD5422
Vout
Iout
AD5422
Fully Integrated
Single-Channel Solution
Vout
Iout
Vout
Iout
Vout
Iout
Vout
Iout
AD5755
Fully Integrated
Quad Channel Solution NEW
 Significant reduction in board area
 Minimal External Components Required
 Manages and Reduces Power and Heat
Efficiently
 Decreases TTM and Cost of Ownership

51. Universal Output Module with Embedded
Dynamic Power Control Technology
4 Channels Enabled Driving 20 mA into Zero Ohm Load:
 Case 1: without dc-to-dc control enabled (pink)
 Case 2: with dc-to-dc control enabled (blue)
On-Chip Die Temperature Low When DC-to-DC Regulation Enabled
56
AD5755
Change in Temperature calculations
-50
0
50
100
150
200
250
0 5 10 15 20 25 30
Time (s)
delatT(°C)
DC/DC 0 Ohm VBOOST 30V 200Ohms
In Production

52. System Outputs—Most Common Architecture
Main
Micro
BUS
System Power -
24 V Nom
DAC
Signal
Isolation
DC-DC Isolated
Power Stage
28V
3.3V
ADP2441
-28V
5V
ADUM2485
Watchdog
Supervisor
DAC
DAC
DAC
.
.
.
.
20ma @ 1K
Analog Outputs:
Driving 20 ma into 1 K load needs 20 V compliance.
Adding headroom supply for DAC; Supply ~ 24 V.
Including output regulation of the power stage a
good estimate is 28 V.
A short is a valid condition. This is mainly because
ADC modules can be terminated with resistor values
as low as 20 Ω for sensing.
Therefore, an 8-channel module can dissipate up to
4 W from the analog portion alone.
Include power losses from the dc-to-dc stage (say
80%) power loss can reach >6 W for the analog
portion alone.
58

53. Precision 16-Bit DAC
AD5755 Block Diagram Dynamic Power Control
Diagnostics
I
30V
0-24mA
0 Ω load
I
5V
24mA
0Ω load
DC-DC
Voltage and
Power is
Dynamically
Adjusted
Smart and High Efficiency
Dynamic Power Control
(DPC)
59

54. Dynamic Power Control
DAC
Main
Micro
BUS
System Power -
24 V Nom
L
Signal
Isolation
DC-DC Isolated
Power Stage
15V
3.3V
ADP2441
-15V
5V
ADUM2485
Watchdog
Supervisor
20mA at
0ΩDC-DC
C L
DAC
L
20mA at
0ΩDC-DC
C L
AD5755
QUAD DAC
The addition of a per dc-to-dc to implement
dynamic power control allows for individual
power losses per channel to be minimized.
Under a short condition for eight channels, the
dc-to-dc regulates the output to 7.5 V, thereby
limiting both on-chip power dissipation and
module power dissipation.
Assuming a dc-to-dc isolated stage of 80%, the
total power dissipated using the dynamic power
control for the 8-channel module is 3 W.
60

55. AD5755/AD5757 Output Ripple
 Waveform of
output ripple
 Yellow = IOUT
 Blue = VBOOST
(at 20 mA dc, 1 kΩ
load)
Per Channel DC-to-DC Circuitry Circuitry at IOUT
 Example of
settling “shape”
(0 mA to 20 mA, 1 kΩ
load)
 With 0 nF capacitor at IOUT
 7.6 mVp-p output ripple at 20 mA dc
 ≈ 580 µs settling time
 With 1 nF capacitor at IOUT
 4.24 mV p-p output ripple at 20 mA dc
 ≈ 580 µs settling time
 With 10 nF capacitor at IOUT
 1.68 mVp-p output ripple at 20 mA dc
 ≈ 660 µs settling time
61

56. Programmable Logic Controllers
62
Analog Inputs
Trends in Analog Inputs
 Better Robustness:
 Overvoltage Protection
 Better Rejection of 50 Hz/60 Hz
 High Speed/Performance ADC Cores

57. PLC/DCS Analog Inputs—Input Signals
10 V
 0 V to 10 V
 ±10 V
20 mA
 Industrial standard
 4 mA to 20 mA loop
 0 mA to 20 mA loop
RTD
 Resistive temperature device
 Pt100, Ni1000, Cu10, …
Thermocouple
 Two metals connected together
 Low voltage (mV) ~ (T1-T2)
 Second temperature sensor (CJC)
10 V DC
0 – 10V
AIN
SENSOR
24 V DC AIN
ADC
AIN
A
ADC
ADC
DIVIDER
EXCITATION ~mA
AIN
A ADC
T1 T2
Metal A
Metal B
Copper
Copper
Sens.
(CJC)
Rsens
63

58. ADA4096-x – 36V OPX96 Performance 36V, RRIO,
Precision, µPower, RRIO Op Amp with OVP
 Key Features
 Internal input overvoltage protection (OVP)
 Up to ±32 V beyond the rails
 Characterized OVP parametric impact
(compared to external OVP solutions)
 Low power: 60 µA typical
 Unity GBW:800 kHz at Vsy = ±15V typical
550 kHz at Vsy = ±5 V typical
475 kHz at Vsy = ±1.5 V typical
 Low offset voltage: 35 µV typical
 Applications
 Process control (PLC/DSC)
 Battery monitoring and current shunt sensing
 Sensor conditioning
 Portable instrumentation
 Wireless base stations
64
Isy GBW Vos Vos Drift Noise IB Voltage Temp Range
75 µA max 800 kHz typ 300 µV max 1 µV/°C typ 27 nV/√Hz typ 25 nA max 3 V to 30 V ˗40°C to 125°C
ADA4096-2 Dual Released ADA4096-4 Quad Production
 Package: MSOP-8, LFCSP-8 (3 × 3)
 List Price: $1.87 at 1k units
 Package: TSSOP-14, LFCSP-14 (3 × 3)
 List Price: $2.70 at 1k units
ADI Advantages
With 2× the BW, ½ Vos and 1/3 TcVos, ½ Vn of
the closest competition, and 32 V Input OVP; the
ADA4096 provides the industry’s highest level of
overvoltage protection for robust operation in
demanding I&I applications

59.  External Diode Protection
 Advantage
 Cheap solution
 Disadvantage
 Not suitable for some
applications
(i.e. precision)
 Variable leakage current
 Variable capacitance
 Increase in nonlinearity
 Need external circuitry
 Differential Diode Protection
 Advantage
 Cheap solution
 Constant leakage
current and
capacitance
 Disadvantage
 Need external circuitry
 Does not work when powered off
 Large Rlimit resistance will add noise to the
system
 ADI OVP Solution
 Advantage
 Integrated OVP solution
 Provides most, if not all
protection needed
 Saves board area
 Prevents phase inversion beyond IVR
 Disadvantage
 Might need extra external protection for
OVP beyond the protection limits
Surveying Various Internal and External OVP
Solutions
 Internal ESD Protection
 Advantage
 Cheap solution
 Disadvantage
 Not robust enough
65
ADA4096

60. ADI’s OVP Op Amps
Overvoltage protection op amps:
 The most robust solution available
 Effects are included in data sheet specifications
 No phase inversion to the protection limits
(beyond the IVR)
 No external circuitry required
 Protects indefinitely and with power on or off
It is able to protect op amps and entire circuitry from:
 Input voltages above supply rails
 Manufacturing shorts
 Human error
 Transducers which produce voltages higher than supply rails
OVP is able to protect circuits from various unexpected errors,
which in turns saves $$
66
ADA4091 ADA4096

61. Analog to Digital Converter
Programmable Logic Controllers
67

62. AD7176
Flexible Filter Options
Sinc3
Sinc5+
Sinc1
Enhanced
Filters
AD7176  Maximize 50 Hz/60 Hz rejection
 Reduced settling time
 Improved channel switch rates
 50 Hz and 60 Hz combined
 Standard SD ADC filter
 Best noise performance and resolution
 Best choice for single channel high resolution
 Performs best at lower speeds
 New filter design
 Fast channel switching with quickest settling
 Best performance at higher speeds
68

63. Improved Interface Robustness
CS rising edge resets the serial interface into a known state
 No reset required if interface synchronization is lost
Writing to AD7176 Reading from AD7176
CRC checksum prevents data corruption on digital interface
 Work on both reads and writes
Internal register checksum
 Validation of ADC configuration
69

64. Enhanced Filtering Simultaneous Rejection
of 50 Hz and 60 Hz
Multichannel 50 Hz/60 Hz Rejection
Fastest 50 Hz/60 Hz Rejection on the Market
Output
Data
Rate (SPS)
tSETTLE
(ms)
Ch. Switch Rate
=1/tSETTLE (Hz)
Rej. Of
50 Hz and
60 Hz
(±1 Hz) (dB)
AD7176 Noise-
Free Bits
27.27 36.67 27.27 47 23.3
25 40.0 25 62 23.3
20 50.0 20 85 23.5
16.667 60.0 16.667 90 23.5
Trading Faster Channel Switch Rates vs. Rejection
70

65. Motor Control/Data Acquisition: Faster Speed/
Robotics, Set Point Control
71
ADC
Rsens
~250 Ω
4mA to 20mA
ANALOG
INPUT
FIELD
INSTRUMENT
(SENSOR)
2-WIRE CONNECTION
DAC
ANALOG
OUTPUT
4mA to 20mAFIELD
INSTRUMENT
(ACTUATOR)
2-WIRE CONNECTION
1K
IO MODULE
FASTER SETTLING
PRODUCTIVITY
EFFICIENCY
CONTROL

66. Sinc5 + Sinc1 Filter
Maximizing Channel Switch Rate
 Multichannel applications
 Max channel switch rate = 50 kSPS/channel
 Single cycle settling at < 10 kSPS ODR
Output Data
Rate (ODR) (SPS)
tSETTLE
Switching Rate
(SPS)
F Notch
(Hz)
Noise (µV RMS)
Resolution (p-p)
Noise-Free bits
(5 V Vref)
250,000 20 µs 50,000 250,000 9.7 17.25
50,000 36 µs 27,778 50,000 5 18.2
25,000 56 µs 17,857 25,000 3.6 18.7
15,625 80 µs 12,500 15,625 2.7 19.1
10,000 100 µs 10,000 11,905 2.5 19.2
1,000 1.0 ms 1,000 1,016 0.82 20.8
100 10.0 ms 100.0 100.16 0.46 21.7
59.94 16.68 ms 59.94 60.00 0.43 21.7
49.96 20.016 ms 49.96 50.00 0.42 21.8
16.667 60.02 ms 16.66 16.67 0.42 21.8
5 200.02 ms 5.00 5.00 0.32 22.1
66

67. AD7176-2, 24-Bit, 250 kSPS, 20 µs Settling Σ-Δ ADC
 Fast and Flexible Output Data
Rates 5 SPS to 250 kSPS
 17.2 noise-free bits at 250 kSPS
 Flexible filter options
 Fastest 50 Hz/60 Hz rejection
 Fast settling—50 kSPS/channel scan rate
 INL 2.5 ppm typical
 Integrated 2.5 V reference (2 ppm) and
oscillator
 Per channel configuration and calibration
 Cross point mux with automatic sequencing
AIN 0
AIN 1
AIN 2
AIN 3
AIN 4
AVSS
Crosspoint
Multiplexer
AVDD
Σ-Δ ADC
AVSS
SERIAL
INTERFACE
& CONTROL
CS
SCLK
DIN
DOUT/RDY
SYNC/ERROR
I/O
CONTROL
GPIO 0 GPIO 1
AVDD1 AVDD2
1.8V
LDO
REGCAP A IOVDD
1.8V
LDO
REGCAP D
DGND
Buffered
Precision
Reference
REF+REF- REFOUT
XTAL1 CLKIO/XTAL2
XTAL & INTERNAL
CLOCK OSCILLATOR
CIRCUITRY
AD7176-2
INT
REF
DIGITAL
FILTER
Noise-Free
P-P Bits
Channel
Switch Rate
17.2 50 kSPS
18.5 31 kSPS
20.2 2.5 kSPS
23.5 20 SPS
73

68. Process Control Demo
Demo Station
74

69. Demonstration Overview
75

70. Loop-Powered, 4 mA to 20 mA + HART Interface
with AD5421 + AD5700 (CN0267)
Description and Benefits:
 4 mA to 20 mA loop is the standard
interface for communicating
measured values from sensors to a
controller
 HART (Highway Addressable
Remote Transducer) protocol is the
global standard for sending and
receiving digital information across
analog wires
 The HART communication enables
better diagnostic capabilities and
asset management
 Improve the overall system reliability
and efficiency
Inputs:
 4 mA to 20 mA loop
 Standard resistive pressure sensor
End
Market
Target
Applications
Key Parts
Used
• Industrial
• Field
instruments
• Smart
transmitter
• AD5700
• AD5421
• ADUCM360
Available
now
76
This demo board is available for purchase:
www.analog.com/DC13-hardware

71. DEMO-AD5700-D2Z—Complete ADI Solution
for Industrial HART Communication
(Transmitter Side)
AD5700
HART
Modem
SPIADC
UART
AIN(+)
AIN(–)
3.3V
50Ω
DAC
LOOP(–)CIN
V-REG
HART OUT
HART IN
3.3V
COM
3.3V
AD5421ADuC
uC
CHART
CSLEW
+
–
UART
REGIN
0-100%
SPI
REGOUT
Analog
Input
Simulation
CFILTER
77

72. Isolated, Single Channel Universal Analog Input
(Voltage, Current, Thermocouple, RTD) with
Overvoltage Protection (CN0325)
Description and Benefits:
 Single channel analog front end
for process control systems
 Overvoltage protection
 Universal analog input
 Channel-to-Channel isolation
Inputs:
 Voltage
 Current
 Temperature (thermocouple + RTD)
End Market Target
Applications
Key Parts
Used
• Industrial • PLC/DCS • AD7795
• ADuM3471
• ADT7310
Available now
78
This demo board is available for purchase:
www.analog.com/DC13-hardware

73. Isolated (ADUM347x), Single Channel, Voltage
and Current Output (AD5422) with HART
(AD5700) Suitable for Channel-to-Channel
Isolated Systems (CN0321)
Description and Benefits:
 Single channel analog output for
process control systems
 HART enabled
 Current and voltage output ranges
 Channel-to-Channel isolation
Inputs:
 Digital inputs
End Market
Target
Applications
Key Parts
Used
• Industrial • PLC/DCS
• ADUM3471
• AD5422
• AD5700
Available now
79
This demo board is available for purchase:
www.analog.com/DC13-hardware

74. Tweet it out! @ADI_News #ADIDC13
What We Covered
Introduction to Industrial Control
Understand Field Instruments and PLC/DCS
Market Trends and ADI Products to Support This
Demo of ADI Process Control Boards
80

75. Reference Circuits
Some Other Relevant Circuit Notes for Process Control:
 Transmitters
 Complete closed-loop precision analog microcontroller thermocouple
measurement system with 4 mA to 20 mA output (CN0300)
 4 mA to 20 mA loop-powered temperature monitor using the
ADuC7060/ADuC7061 precision analog microcontroller (CN0145)
 Complete thermocouple measurement system using the AD7793 24-bit
Sigma-Delta ADC (CN0206)
 EMC Compliant RS-485 transceiver protection circuits (CN0313)
 PLC/DCS
 Precision 24-bit, 250 kSPS single-supply Sigma-Delta ADC system for
industrial signal levels, using the AD7176 (CN0310)
 Software configurable, universal analog front end for industrial and sensor
data acquisition (CN0209)
 High accuracy multichannel thermocouple measurement solution (CN0172)
 4 channels, flexible, configurable, voltage and current output circuit for I/O
card and PLC applications (CN0229)
81