CN0229 AD | Alldatasheet
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information and/or support, visit www.analog.com/CN0229. Fax: 781.461.3113 ©2012 Analog Devices, Inc. All rights reserved. Figure 1. Simplified Schematic of the Analog Output Circuit (All Connections and Protection Circuits Not Shown)
Rev. 0 | Page 2 of 6 EVALUATION AND DESIGN SUPPORT Circuit Evaluation Boards CN-0229 Circuit Evaluation Board (EVAL-CN0229-SDPZ) System Demonstration Platform (EVAL-SDP-CB1Z) Design and Integration Files Schematics, Layout Files, Bill of Materials CIRCUIT FUNCTION AND BENEFITS The circuit shown in Figure 1 is a multichannel, flexible, analog output solution with only two analog components and meets most requirements for multichannel I/O cards, programmable logic controllers (PLCs), and distributed control systems (DCSs) applications. The AD5686R quad, 16-bit nanoDAC+ with rail- to-rail buffered outputs combined with four of the AD5750-2 industrial current/voltage output drivers provide all the typical output current and voltage ranges with 16-bit resolution, no missing codes, 0.05% linearity, and less than 0.1% output error. An ultralow drift (2 ppm/°C typical), 2.5 V voltage reference with high drive capability (up to ±5 mA) is integrated in the AD5686R and provides the reference voltage for both the AD5686R and the AD5750-2. This guarantees low noise, high accuracy, and low temperature drift for the circuit. The ADuM1301 and ADuM5400 provide 2500 V rms isolation both on power, and all the necessary signals between the analog signal chain and the host controller. For multichannel I/O card applications that need more than 4 channels, several AD5686Rs can be connected in a daisy chain, and no additional external digital I/O circuits are required. This minimizes the cost, especially for high channel count isolated applications. The circuit also contains key features for industrial applications, such as on-chip output fault detection, packet error checking (PEC) by the CRC, flexible power-up options, and ESD protection (4 kV for the AD5686R, human body model and 3 kV for the AD5750-2, human body model), making it an ideal choice for robust industrial control systems. No external precision resistors or calibration routines are needed to maintain consistent performance in mass production, thereby making it ideal for PLC or DCS modules. CIRCUIT DESCRIPTION The AD5750/AD5750-1/AD5750-2 are single-channel, low cost, precision voltage/current output drivers developed to meet the requirements of industrial process control applications. The output voltage range can be programmed for the standard output ranges for PLC and DCS applications: 0 V to 5 V , 0 V to 10 V , −5 V to +5 V , and −10 V to +10 V . A 20% overrange setting is also provided for the standard ranges, giving the following options: 0 V to +6 V , 0 V to +12 V , −6 V to +6 V , and −12 V to +12 V . The current output, which is provided on a separate pin, can be programmed for the ranges of +4 mA to +20 mA, 0 mA to +20 mA, −20 mA to +20 mA, 0 mA to +24 mA, and −24 mA to +24 mA. The unipolar ranges have a 2% overrange setting. Because the AD5750/AD5750-1/AD5750-2 current outputs can either source or sink current, they can interface to a wide variety of sensors or actuators. The voltage and current output pins can be connected together to configure the system as a single-channel output if desired. Generally, the current output circuit needs at least one precision resistor for current sensing. The current accuracy and temperature drift characteristic of the circuit depends partly on the resistor as well as the reference. The AD5750/AD5750-1/AD5750-2 integrates the high precision, low drift resistor and still allows the use of an external resistor, if desired. As a method of improving the stability of the output current over temperature, an external low drift resistor can be connected to the REXT1 and REXT2 pins of the AD5750/AD5750-1/AD5750-2, instead of the internal resistor. The external resistor is selected via the input shift register. If the external resistor option is not used, leave the REXT1 and REXT2 pins floating. The AD5686R is a quad 16-bit nanoDAC+ with rail-to-rail voltage- buffered outputs integrated with an on-chip 2 ppm/°C typical (5 ppm/°C maximum), 2.5 V reference. The on-chip reference can drive the reference input of all four AD5750-2s, has a low output impedance of 0.05 Ω, and can source and sink up to 5 mA. The AD5686R incorporates a power-on reset circuit to ensure that the DAC output powers up to 0 V and remains there until a valid write command takes place. The interface between the AD5686R DAC and the AD5750-2 driver is simple and requires no external voltage reference or precision resistors. The output voltage range of the AD5686R is 0 V to 2.5 V , which matches the input range of the AD5750-2. In addition, the reference output voltage of the AD5686R is 2.5 V , which precisely matches the reference input requirement of the AD5750-2. The ADuM1301 is a triple-channel digital isolator. The ADuM5400 is a quad-channel digital isolator with an integrated, isolated, dc-to-dc converter. They are both based on iCoupler® technology and are used to provide isolation between the signal chain and the system microcontroller, with an isolation rating of 2.5 kV rms. The ADuM5400 provides an isolated 5 V power supply for the 5 V circuits in the secondary side. Devices for PLC and DCS applications generally need ESD protection and overvoltage protection much higher than the formal recommend specifications. The AD5686R and the AD5750-2 have internal ESD protection diodes to each pin that can prevent damage from a 4 kV (AD5686R) and 3 kV (AD5750-2) transient (human body model). However, the industrial control environment can subject I/O circuits to much higher transients.
Table 1. Test Results for All Output Ranges error, which is easily removed by customer calibration. the AD5620 (12 bits), are good choices. CN-0204 circuit notes for more details. driver and can supply a 40 V output using a 50 V AVDD supply.
- System Demonstration Platform (EV AL-SDP-CB1Z)
- CN-0229 Circuit Evaluation Board (EV AL-CN0229-SDPZ)
- CN-0229 Evaluation Software
- Agilent 34401A 6.5 Digital Multimeter
- Agilent E3631A 0 V to ~6 V/5 A ±25 V/1 A Triple Output DC Power Supply
- PC (Windows® 2000 or Windows XP) with USB interface
- National Instruments GPIB to USB-B interface and cable
Readme file for installing and using the evaluation software. http://www.analog.com/CN0229-DesignSupport.
120 PIN SDP
Figure 5. Test Setup Functional Block Diagram Table 2. Jumper Settings for EVAL-CN0229-SDPZ (Bolded Values Are Default Settings) JP1_[CH] VSENSE+ setting Shorting Shorts VSENSE+ with VOUT internally for Channel [CH]. Opening VSENSE+ has no connection with VOUT internally for Channel [CH]. JP2_[CH] VSENSE− setting Shorting Shorts VSENSE− with GND internally for Channel [CH]. Opening VSENSE− has no connection with GND internally for Channel [CH]. JP3_[CH] Shorting Shorts VOUT and IOUT together for Channel [CH]. IOUT pins Opening VOUT and IOUT have no connection internally for Channel [CH]. JP4_[CH] Shorting Adds an 1 nF compensation capacitor for Channel [CH]. compensation capacitor Opening Removes an 1 nF compensation capacitor for Channel [CH].
Rev. 0 | Page 6 of 6 Test After setting up the test equipment, connect the VOUT pin of CN3 or the IOUT pin of CN4 to the input of the Agilent 34401A. Ensure that the cable connection on the front panel of Agilent 34401A is correct, depending on the different input signal type (current or voltage). Testing the INL, DNL, and output error takes a considerable amount of time because all the AD5686R 16-bit DAC levels must be set and measured by the Agilent 34401A. The software provided on the CD allows the DAC codes to be set by the PC. An automatic test program is necessary to step through the codes and analyze the data. This is not provided on the CD but must be implemented by the customer to correspond to the requirements of the particular multimeter used in the test setup. In the test configuration shown in Figure 5, the GPIB output of the Agilent 34401A multimeter interfaces to a second USB port on the PC using the National Instruments GPIB to USB-B interface and cable. This allows the multimeter readings corresponding to each code to be loaded into an Excel spreadsheet in the PC. The data is then be analyzed for INL, DNL, and output error using industry-standard definitions. For more details on the definitions and how to calculate the INL, DNL, and output error from the measured data, see the Terminolog y section of t he AD5686R data sheet and the Data Conversion Handbook, "Testing Data Converters," Chapter 5, Analog Devices. LEARN MORE CN-0229 Design Support Package: http://www.analog.com/CN0229-DesignSupport Slattery, Colm, Derrick Hartmann, and Li Ke, "PLC Evaluation Board Simplifies Design of Industrial Process Control Systems. ” Analog Dialogue (April 2009). CN-0202 Circuit Note, Flexible High Accuracy, Low Drift, PLC/DCS Analog Output Module. CN-0203 Circuit Note, Flexible PLC/DCS Analog Output Module Using Only Two Analog Components. CN-0204 Circuit Note, Flexible, High Voltage, High Accuracy, Low Drift PLC/DCS Analog Output Module. CN-0063 Circuit Note, 16-Bit Fully Isolated Voltage Output Module Using the AD5662 DAC, ADuM1401 Digital Isolator, and External Amplifiers, Analog Devices. CN-0064 Circuit Note, 16-Bit Fully Isolated 4 mA to 20 mA Output Module Using the AD5662 DAC, ADuM1401 Digital Isolator, and External Amplifiers, Analog Devices. CN-0065 Circuit Note, 16-Bit Fully Isolated Output Module Using the AD5422 Single Chip Voltage and Current Output DAC and the ADuM1401 Digital Isolator, Analog Devices. CN-0066 Circuit Note, Fully Isolated Input Module Based on the AD7793 24-Bit Σ-Δ ADC and the ADuM5401 Digital Isolator, Analog Devices. CN-0067 Circuit Note, Fully Isolated Input Module Based on the AD7793 24-Bit Σ-Δ ADC, the ADuM5401 Digital Isolator, and a High Performance In-Amp, Analog Devices. CN-0097 Circuit Note, Simplified 12-Bit Voltage and 4 mA-to-20 mA Output Solution Using the AD5412, Analog Devices. CN-0209 Circuit Note, Fully Programmable Universal Analog Front End for Process Control Applications, Analog Devices. AN-0971 Recommendations for Control of Radiated Emissions with isoPower Devices by Mark Cantrell MT-031 Tutorial, Grounding Data Converters and Solving the Mystery of “ AGND” and “DGND”, Analog Devices. MT-101 Tutorial, Decoupling Techniques, Analog Devices. Wa lt Ke ster, Practical Design Techniques for Sensor Signal Conditioning, Analog Devices, 1999, ISBN 0-916550-20-6 Wa lt Ke ster, Data Conversion Handbook, Chapter 5, Analog Devices. Data Sheets and Evaluation Boards CN-0229 Circuit Evaluation Board (EV AL-CN0229-SDPZ) System Demonstration Platform (EV AL-SDP-CB1Z) AD5750-2 Data Sheet and Evaluation Board AD5686R Data Sheet and Evaluation Board ADuM5400 Data Sheet and Evaluation Board ADuM1301 Data Sheet and Evaluation Board
REVISION HISTORY
4/12—Rev. 0: Initial Version (Continued from first page) Circuits from the Lab circuits are intended only for use with Analog Devices products and are the intellectual property of Analog Devices or its licensors. While you may use the Circuits from the Lab circuits in the design of your product, no other license is granted by implication or otherwi se under any patents or other intellectual property by application or use of the Circuits from the Lab circuits. Information furnished by Analog Devices is believed to be accurate and reliable. However, Circuits from the Lab circuits are supplied "as is" and without warranties of any kind, express, implied, or statutory including, but not limited to, any implied warranty of merchantability, noninfringement or fitness for a particular purpose and no responsibility is assumed by Analog Devices for their use, nor for any infringements of patents or other rights of third parties that may result from their use. Analog Devices reserves the right to change any Circuits from the Lab circuits at any time without notice but is under no obligation to do so. ©2012 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the prop erty of their respective owners. CN10099-0-4/12(0)