Circuit Note CN-0229 Devices Connected/Referenced AD5750-2 Industrial Current/Voltage Output Driver with Programmable Ranges Circuits from the Lab reference circuits are engineered and tested for quick and easy system integration to help solve todays AD5686R Quad, 16-Bit nanoDAC+ with 2.5 V, analog, mixed-signal, and RF design challenges. For more 2 ppm/C On-Chip Reference information and/or support, visit www.analog.com/CN0229. ADuM5400 Quad-Channel Isolator with Integrated DC-to-DC Converter ADuM1301 Triple-Channel Digital Isolator 4-Channel, Flexible, Configurable, Voltage, and Current Output Circuit for I/O Card and PLC Applications FAULT INDICATOR 15V +15V AD5750-2 OUTPUT RANGES: DV AV AV CC DD SS VOUT: FAULT AD5750-2 0V TO 5V, 0V TO 10V, VREF 5V, 10V VOUT VOUT RANGE SCALE VIN IOUT: 0mA TO 20mA IOUT IOUT +5V +5V ISO 0mA TO 24mA RANGE SCALE 4mA TO 20mA ADuM1301 20mA, 24mA GND SYNC1 SCLK SCLK SDIN SDIN SDO SDO 15V +15V DV AV AV CC DD SS V V DD GND REF VREF FAULT AD5750-2 VOUT AD5686R/AD5685R/AD5684R 2.5V VIN REFERENCE V GND LOGIC IOUT V A STRING OUT INPUT DAC +15V 15V DAC A REGISTER REGISTER SCLK BUFFER DV AV AV CC DD SS V B STRING OUT INPUT DAC VREF SYNC FAULT DAC B REGISTER REGISTER AD5750-2 BUFFER VOUT VIN ADuM5400 GND SDIN IOUT V C STRING OUT INPUT DAC DAC C REGISTER REGISTER 15V +15V BUFFER SDO SYNC1 V D STRING OUT INPUT DAC SYNC2 AV AV DV DD SS REGISTER REGISTER DAC D CC LDAC VREF FAULT BUFFER RESET AD5750-2 VOUT POWER-ON GAIN POWER- VIN RESET 1/2 DOWN GND IOUT LOGIC LDAC RESET RSTSEL GAIN Figure 1. Simplified Schematic of the Analog Output Circuit (All Connections and Protection Circuits Not Shown) Rev. 0 Circuits from the Lab circuits from Analog Devices have been designed and built by Analog Devices engineers. Standard engineering practices have been employed in the design and construction of each circuit, and their function and performance have been tested and verified in a lab environment at room temperature. However, you are solely responsible for testing the circuit and determining its One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. suitability and applicability for your use and application. Accordingly, in no event shall Analog Devices Tel: 781.329.4700 www.analog.com be liable for direct, indirect, special, incidental, consequential or punitive damages due to any cause Fax: 781.461.3113 2012 Analog Devices, Inc. All rights reserved. whatsoever connected to the use of any Circuits from the Lab circuits. (Continued on last page) INTERFACE LOGIC SYNC SCLK SDIN SDO 10099-001CN-0229 Circuit Note The current output, which is provided on a separate pin, can EVALUATION AND DESIGN SUPPORT be programmed for the ranges of +4 mA to +20 mA, 0 mA to Circuit Evaluation Boards +20 mA, 20 mA to +20 mA, 0 mA to +24 mA, and 24 mA CN-0229 Circuit Evaluation Board (EVAL-CN0229-SDPZ) to +24 mA. The unipolar ranges have a 2% overrange setting. System Demonstration Platform (EVAL-SDP-CB1Z) Design and Integration Files Because the AD5750/AD5750-1/AD5750-2 current outputs can Schematics, Layout Files, Bill of Materials either source or sink current, they can interface to a wide variety of sensors or actuators. The voltage and current output pins can be CIRCUIT FUNCTION AND BENEFITS connected together to configure the system as a single-channel The circuit shown in Figure 1 is a multichannel, flexible, analog output if desired. output solution with only two analog components and meets Generally, the current output circuit needs at least one precision most requirements for multichannel I/O cards, programmable resistor for current sensing. The current accuracy and temperature logic controllers (PLCs), and distributed control systems (DCSs) drift characteristic of the circuit depends partly on the resistor as applications. The AD5686R quad, 16-bit nanoDAC+ with rail- well as the reference. The AD5750/AD5750-1/AD5750-2 integrates to-rail buffered outputs combined with four of the AD5750-2 the high precision, low drift resistor and still allows the use of an industrial current/voltage output drivers provide all the typical external resistor, if desired. As a method of improving the stability output current and voltage ranges with 16-bit resolution, no of the output current over temperature, an external low drift missing codes, 0.05% linearity, and less than 0.1% output error. resistor can be connected to the REXT1 and REXT2 pins of the An ultralow drift (2 ppm/C typical), 2.5 V voltage reference with AD5750/AD5750-1/AD5750-2, instead of the internal resistor. high drive capability (up to 5 mA) is integrated in the AD5686R The external resistor is selected via the input shift register. If the and provides the reference voltage for both the AD5686R and external resistor option is not used, leave the REXT1 and the AD5750-2. This guarantees low noise, high accuracy, and REXT2 pins floating. low temperature drift for the circuit. The AD5686R is a quad 16-bit nanoDAC+ with rail-to-rail voltage- The ADuM1301 and ADuM5400 provide 2500 V rms isolation buffered outputs integrated with an on-chip 2 ppm/C typical both on power, and all the necessary signals between the analog (5 ppm/C maximum), 2.5 V reference. The on-chip reference signal chain and the host controller. can drive the reference input of all four AD5750-2s, has a low output impedance of 0.05 , and can source and sink up to 5 mA. For multichannel I/O card applications that need more than The AD5686R incorporates a power-on reset circuit to ensure 4 channels, several AD5686Rs can be connected in a daisy chain, that the DAC output powers up to 0 V and remains there until a and no additional external digital I/O circuits are required. This valid write command takes place. minimizes the cost, especially for high channel count isolated applications. The interface between the AD5686R DAC and the AD5750-2 driver is simple and requires no external voltage reference or The circuit also contains key features for industrial applications, precision resistors. The output voltage range of the AD5686R is such as on-chip output fault detection, packet error checking (PEC) 0 V to 2.5 V, which matches the input range of the AD5750-2. by the CRC, flexible power-up options, and ESD protection (4 kV In addition, the reference output voltage of the AD5686R is 2.5 V, for the AD5686R, human body model and 3 kV for the AD5750-2, which precisely matches the reference input requirement of the human body model), making it an ideal choice for robust industrial AD5750-2. control systems. No external precision resistors or calibration routines are needed to maintain consistent performance in mass The ADuM1301 is a triple-channel digital isolator. The ADuM5400 production, thereby making it ideal for PLC or DCS modules. is a quad-channel digital isolator with an integrated, isolated, dc-to-dc converter. They are both based on iCoupler technology CIRCUIT DESCRIPTION and are used to provide isolation between the signal chain and The AD5750/AD5750-1/AD5750-2 are single-channel, low cost, the system microcontroller, with an isolation rating of 2.5 kV rms. precision voltage/current output drivers developed to meet the The ADuM5400 provides an isolated 5 V power supply for the requirements of industrial process control applications. The output 5 V circuits in the secondary side. voltage range can be programmed for the standard output ranges Devices for PLC and DCS applications generally need ESD for PLC and DCS applications: 0 V to 5 V, 0 V to 10 V, 5 V to protection and overvoltage protection much higher than the +5 V, and 10 V to +10 V. A 20% overrange setting is also provided formal recommend specifications. The AD5686R and the for the standard ranges, giving the following options: 0 V to AD5750-2 have internal ESD protection diodes to each pin +6 V, 0 V to +12 V, 6 V to +6 V, and 12 V to +12 V. 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. Rev. 0 Page 2 of 6