Process Control Circuits from the Lab Reference Circuits Contents Overview Overview .......................1 For over 40 years, designers of industrial process control systems and Analog Devices have worked together to define, develop, and deploy complete signal chain solutions, optimized for a wide array PLC Challenges .................2 of applications. We bring reliability and innovation to this process with precision control and monitor- Input Module ...................4 ing solutions based on our industry-leading technologies and systems-level expertise. Now you can quickly implement turnkey process control building blocks with Circuits from the Lab™ reference Output Module .................10 circuits from Analog Devices. Industrial Automation ............15 Circuits from the Lab reference circuits are engineered and tested for quick and easy system integra- PLC Reference Design ...........19 tion to help solve today’s analog, mixed-signal, and RF design challenges. Each circuit is carefully Circuits from the Lab documented with test data, design considerations, and evaluation setup; many circuits also include Reference Circuit Tips ...........20 free design files and low cost evaluation hardware. Analog Devices has developed hundreds of reference circuits. This brochure includes a collection of these circuits specific to process control. Visitwww.analog.com/circuits for the full collection. www.analog.com/circuitsPCTL-br PLC Challenges Industrial Programmable Logic Controller (PLC) System Design Considerations and Challenges • Analog input types and ranges can be as small as ±10 mV for TC • The resolution and accuracy of the input/output modules typically (thermocouple) and strain gage and as large as ±10 V for actuator range from 12- to 16-bit, with 0.1% accuracy over the industrial controllers— or 4 mA to 20 mA currents in process control systems. temperature range. • Analog output types and ranges typically include ±5 V, ±10 V, 0 V to • Connectivity to different types of industrial networks, (for example, 5 V, 0 V to 10 V, 4 mA to 20 mA, and 0 mA to 20 mA. Sometimes over- analog, Fieldbus, CAN, Ethernet, USB). Isolation between system power range capability is required. module and low power electronics; between input and output; between I/O and central control unit. Isolation grade varies from 1 kV to 2.5 kV. Reference Circuits for PLC Input Module Output Module CN0213 +5V CN0191 0.1F +15V 1F PRECISION R1 1/2 5V DC + AD8676B SOURCE 1.5k C1 + A1 1/2 7 +4.25V 10F +3.3V +15V – AD8676B +10V AD8275 +V +2.25V 10 F 10 F S – −15V + + *OMIT RG +0.25V VIO + B1 FOR G = 1 50k 10k R3 +15V −15V 0V 2 5 1k 0.1F 0.1F +15V –IN SENSE VDD VIO R2 1k −10V IN+ SDI 10 9 5 4 3 20 OUT 7 CLR +15V –10V TO 6 SCK RFB CC DD AD7685 CC +10V AIN− SDO V V 8 LDAC OUTPUT +2.25V REFPF REFPS 1 IN– IOV INV – V CNV V VOLTAGE REF GND 11 SDO C1 50k 20k SPI INTERFACE 2 3 8 AND DIGITAL 14 SYNC VOUT + *RG AD5791B AD8675A +IN REF2 CONTROL 20k 13 SCLK AD8226 REF 1 0.1F 10F −15V REF1 12 SDIN –V SS REFNF S REFNS V V AIN+ AGND DGND V 4 6 RESET −15V 15 18 16 17 19 R5 +15V 0.1F +15V 2k +5V R4 B2 ADP1720 ADR439 1k + + – +4.5V – V V –15V 10F IN OUT IN OUT A2 1/2 AD8676B EN + GND GND 1/2 AD8676B Complete analog front end (AFE) with high precision 20-bit, linear, low noise, precision, bipolar 10 V dc voltage and high CMRR provided by AD7685, AD8226, and source provides industry-leading INL and DNL, with guaranteed AD8275 (CN0213). See Page 4. monotonicity, low power, and small size (CN0191). See Page 10. ADP1720 REF194 +5V CN0209 +4.5V CN0179 +15V AVDD +15 VIN VOUT VIN VOUT F F F 10 F 0.1 F F + +2.25V 10 1k 10 AGND 0.1 F 0.1 V F GND2 SY GND2 GND2 SUPPLY 10 0.1F GND2 0.1 4-20_1 1k 18V AVDD –15 J1-5 –15V 200 +5V ADT7310 J1-4 J1-6 GND2 0.1F 10k 10k R1 R2 J1-1 J2-5 4-20_2 SCLK SCLK VDD ADG1414 CURRENT GND2 1k 100 CHANNEL 1&2 200 DOUT DOUT CT ADR125 S1 D1 INT1 VREF 0.1% 0.1% J1-2 J2-6 DIN DIN INT 5V CHANNEL 1 INT2 S2 D2 +5V 10ppm/°C 10ppm/°C ADT7310 CS GND VIN VOUT J1-3 1/2 GND2 S3 D3 +2.25V AD8617 11.5k 10F 0.1F 0.1F 10F S4 D4 J2-1 GND2 GND2 +5V GND S5 D5 +4.5V +5V +3.3V 18V ZENER J2-4 1/2 ADuM1400 REFIN1+ REFIN1– AVDD DVDD BZX84C18 S6 D6 +2.25V AD8617 1/2 J2-2 11.5k VDD2 VDD1 S7 D7 GND2 GND2 P3 P3 GDD2 GND1 AD8657 IRFU9014 CHANNEL 2 SCLK VOA VIA SCLK_I P2 P2 A2 100 S8 D8 AD7193 DIN VOB VIB DIN_I J2-3 ADG1414 V V DIN +15V OC IC ADG1414_I DIN ADT7310 VOD VID ADT7310_I VDD BAS21LT1 SCLK +4.5V VE2 VE1 –INA +V AIN1_0 AIN1 SCLK SCLK SYNC SCLK GND2 GND1 SYNC +5V AIN2_0 AIN2 +INA OUTA DIN DIN VDAC ADG1414 +15V REF2 –15V GND2 AD8676 AIN3 ADuM1401 SCLK AD5621 VOUT +INB REF1 AD8275 CS AD7193 1/2 ADG442 OUTB 4-20_1 AIN4 V V D1 S1 AIN1_0 –INB DOUT/RDY DOUT DD1 DD2 IRFU024N –V G G AD8657 GND2 ND1 ND2 SDIN AIN5 INT1 V V INT1_I GND A1 IN1 IA OA IOUT INT2 V V INT2_I R P2 –15V AIN6 IB OB LOAD DOUT VIC VOC DOUT_I S2 AIN2_0 MICROCONTROLLER INTERFACE 250 D2 AIN7 AD7193 VOD VID AD7193_I V V IN2 4-20_2 AIN8 E1 E2 R GND1 GND2 SENSE AGND BPDSW DGND 2.49k D3 S3 0.1% GND2 GND1 IN3 GND2 10ppm/°C P3 D4 S4 IN4 –15V GND2 Fully programmable universal analog front end (AFE) supports varied inputs, such as RTD/thermocouple, Less than 200 μA, low power, 4 mA to 20 mA process unipolar/bipolar, and 4 mA to 20 mA input (CN0209). control current loop provides cost effectiveness and See Page 6. low power (CN0179). See Page 11. CN0067 CN0065 ALTERNATE 15VISO INPUT +5V ADR445 ISO BAS70-04LT1 600 AT 100MHz VIN VOUT FERRITE BEAD 10F + 0.1F + 10F 0.1F + 10F 0.1F +5VISO +15VISO –15VISO + 10F 0.1F 20V TVS: R3 ADuM5401 SMBJ20CA 330k 1.5nF 0.1F 10nF 0.1F 10F ISO NPN TRANSISTOR: ISO V V 5V ISO ISO MMBT8099L ISO ISO DD1 + RG MBR0530 +15VISO TVS AD8220 GNDISO GND1 20V TVS: 51k 10nF C 20V S1 AV /DV –15VISO B SMBJ20CA R 1k DD DD CS VOA VIA CS G AINx(+) 10F 0.1F S3 RG SCLK V V SCLK + E 1nF 1N4148 S4 OB IB INPUT REF S2 AD7793 1k 10 1k V + 10F 0.1F 470pF AINx(–) DIN VOC IC 5V 0.1F ISO REFIN(+) REFIN(–) GND DOUT VID VOD DOUT ISO 22nF R1 R2 TO INTERFACE 200pF V RC RL 250, ISO 100k SEL OUT ADuM1401 ISO TVS 0.1F 10nF 10nF ISO ISO MICROCONTROLLER 0.1% GNDISO GND1 0V + 10F 0.1F 20V CURRENT 0.1F 3.3V 25ppm/°C VDD1 VDD2 OUTPUT ISO ISO ISO 0.1F 0.1F AV AV DV REFIN BOOST +5VISO GND GND DD SS CC ISO ISO 0.1 F 1 2 DVCC SELECT SYNC ISO IOUT AD8601 VIA VOA LATCH +2.5VOUT SCLK +VSENSE 600 AT 100MHz ISO 25k VIB VOB SCLK 10 DIN AD5422 FERRITE BEAD ADR441 V 2.5V VIC OC SDIN VOUT 5.1k DOUT (0.5V) 0.1F VOUT VIN V V SDO 0.1F + 10F OD ID CLEAR –VSENSE TVS VOLTAGE ISO 3.3V ISO + V V OUTPUT + EXTERNAL INPUT E1 E2 FAULT CLEAR GND SELECT R C 20V ISO 0V SET COMP 10F 0.1F ISO GND GND ISO 10F 0.1F ISO 1 2 4nF ISO ISO ISO ISO DIGITAL ISOLATOR ISO +15V –15V 15k, 0.1% ISO ISO 20V TVS: 5ppm/°C BAS70-04LT1 SMBJ20CA ISO Distributed control system (DCS) modules that digitize standard current inputs and unipolar input voltage ranges. Fully isolated and based on the AD7793, 16-bit total solution for standard current outputs and unipolar or ADuM5401, and a high performance in-amp bipolar output voltage ranges. Fully isolated for PLCs and DCS (CN0067). See Page 8. designs using the AD5422 and ADuM1401 (CN0065). See Page 13. 2 | Circuits from the Lab Reference Circuits for Process Control Industrial Automation CN0214 CN0180 2.5V USB HEADER ADP3333-2.5 BEAD BEAD 10 5V IN OUT +4.5V 4.7F 4.7F 4.7F +5V 0.1 F 0.1F +10V +2.5V 4V +2.5V +1.8V TO +5V TxD D– FT232R +VS RxD +0.5V D+ VDD VIO AVDD DVDD +IN 0.4x 20 GND IEXC0 0V IN– 20V SDI S2 NC –OUT 270pF SHIELD 1k +IN 0.8x 10 /RST 0.1F 100 SCK 0.01F ADC0 S1 1k 1.3nF BEAD PtRTD nTRST/BM AD8475 AD7982 –10V 270pF SDO NC –IN 0.8x 10 +OUT 20 ADC1 CNV VOCM IN+ FERRITE BEADS: 0.01F –IN 0.4x REF GND 1k @ 100MHz +4.5V TAIYO YUDEN ADuC7061 –VS V + BK2125HS102-T REF +7V TO +18V +5V R 5.62k REF 2.5V 0.1% 4V VREF – 10k ADC2 ADR435 +5V +0.5V ADC3 THERMOCOUPLE 0.1F 10k JUNCTION DAC P1.1/SOUT P1.0/SIN GND TxD RxD Precision single-supply differential ADC driver for USB-based thermocouple temperature monitor with cold industrial-level signals. Perform attenuation, level shifting, junction compensation.