原标题：TI DAC8760 PLC 16位模拟输出模块参考设计方案

　　TI公司的DAC7760和DAC8760是低成本全集成12位和16位数模转换器(DAC), 设计用于满足工业过程控制的要求,输出电流在4 mA-20 mA,0 mA- 20 mA或0 mA - 24 mA或输出电压在0 V-5 V,0 V-10 V,±5 V, 或±10 V,工作温度从–40℃到+125℃,主要用在4 mA-20 mA电流回路,模拟输出模,建筑物自动化相关设备,环境监测和可编逻辑控制器(PLC).本文介绍了DAC7760和DAC8760主要特性,框图, DACx760输出模块(AO)框图和DACx760评估模块主要特性,框图,电路图,材料清单与PCB元件布局图,以及PLC 16位模拟输出(AO)模块参考设计主要特性,电路图和材料清单.

　　16-Bit Analog Output Module Reference Design for Programmable Logic Controllers (PLC)

　　The DAC7760 and DAC8760 are low-cost, precision, fully-integrated, 12-bit and 16-bit digital-to-analog converters (DACs) designed to meet the requirements of industrial process-control applications. These devices can be programmed as a current output with a range of 4 mA to 20 mA, 0 mA to 20 mA, or 0 mA to 24 mA; or as a voltage output with a range of 0 V to 5 V, 0 V to 10 V, ±5 V, or ±10 V, with a 10% overrange (0 V to 5.5 V, 0 V to 11 V, ±5.5 V, or ±11 V). Both current and voltage outputs can be simultaneously enabled while being controlled by a single data register.

　　These devices include a power-on-reset function to ensure powering up in a known state (both IOUT and VOUT are disabled and in a Hi-Z state). The CLR and CLR-SEL pins set the voltage outputs to zero-scale or midscale, and the current output to the low end of the range, if the output is enabled. Zero and gain registers can be programmed to digitally calibrate the device in the end system. The output slew rate is also programmable by register. These devices can superimpose an external HART signal on the current output and can operate with either a single +10-V to +36-V supply, or dual supplies of up to ±18 V. All versions are available in both 6-mm × 6-mm QFN-40 and TSSOP-24 packages.

　　DAC8760主要特性:

　　Current Output: 4 mA to 20 mA; 0 mA to 20 mA; 0 mA to 24 mA

　　Voltage Output:

　　0 V to 5 V; 0 V to 10 V; ±5 V; ±10 V

　　0 V to 5.5 V; 0 V to 11 V; ±5.5 V; ±11 V (10% Overrange)

　　±0.1% FSR Total Unadjusted Error (TUE) Max

　　DNL: ±1 LSB Max

　　Simultaneous Voltage and Current Output

　　Internal 5-V Reference (10 ppm/°C, max)

　　Internal 4.6-V Power-Supply Output

　　Reliability Features:

　　CRC Check and Watchdog Timer

　　Thermal Alarm

　　Open Alarm, Short Current Limit

　　Wide Temperature Range: –40℃ to +125℃

　　6-mm × 6-mm QFN-40; TSSOP-24 Packages

　　DAC8760应用:

　　• 4-mA to 20-mA Current Loops

　　• Analog Output Modules

　　• Building Automation RELATED DEVICES

　　• Environment Monitoring

　　• Programmable Logic Controllers (PLCs)

　　• Field Sensors and Process Transmitters

　　图1. DAC8760框图

　　图2. DACx760输出模块(AO)框图

　　DACx760评估模块

　　This user’s guide describes the characteristics, operation, and use of the DAC7760 and DAC8760 (DACx760) evaluation boards (EMC-EVMs). This user’s guide also discusses how to set up and configure the software and hardware, and reviews various aspects of the program operation. Throughout this document, the terms DAC8760EMC-EVM, evaluation board, evaluation module, and EVM are synonymous with the DACx760EMC-EVM. This user’s guide also includes information regarding operating procedures and input/output connections, an electrical schematic, printed circuit board (PCB) layout drawings, and a parts list for the EVM.

　　图3. DAC8760EVM评估模块外形图

　　图4. DAC8760EVM评估模块框图

　　图5. DAC8760EVM评估模块硬件连接图

　　DAC8760EVM评估模块材料清单:

　　PLC 16位模拟输出(AO)模块参考设计

　　16-Bit Analog Output Module Reference Design for Programmable Logic Controllers (PLC)

　　This reference design provides a complete 4-channel, 16-bit analog output module design for Programmable Logic Controllers (PLCs). It is designed and fully tested to meet IEC61000-4 EMC and surge requirements for industrial automation systems. The small form-factor design implements four 16-bit digital-to-analog converters with integrated output drivers capable of driving several current and voltage output ranges. Digital data and control lines are galvanically isolated from the PLC host using TI’s high-speed, 4242-volt peak, digital isolator technology. The design also includes an over-current protected, isolated power supply providing all necessary module voltages. With full documentation, test results, design files and necessary firmware, the design makes it easier to evaluate complete signal chain performance and reduces time to market.

　　Standard industrial analog output (AO) circuits are dedicated to either voltage or current outputs.

　　AO模块参考设计主要特性:

　　Designed to comply with IEC61000-4 standards for ESD, EFT and Surge

　　4-Channel 16-bit DAC based configurable Analog Outputs

　　Voltage Outputs: ± 10V, 0 - 10V, ± 5V, 0 - 5V

　　Current Outputs: 0 - 20 mA, 4 - 20 mA, 0 - 24mA

　　Voltage Output Accuracy: +/- 0.2% FSR and Current Output Accuracy: +/- 0.2% FSR

　　Designed with output filtering, protection circuitry and integrated 15kV ESD protection

　　24VDC powered with onboard isolated power supplies

　　AO模块参考设计主要应用:

　　• PLC current and voltage output modules

　　• Field Sensors and Process Transmitters

　　图8. PLC 16位模拟输出(AO)模块参考设计测试板TIDA-00118外形图

　　图9. 测试板TIDA-00118框图

　　This reference design using the DAC8760 can output both the standard industrial voltage and current outputs on a single terminal, thus reducing the number of terminals needed from three to two. A combined output succeeds in reducing the wiring cost, connector count, and increasing the versatility of the AO design.

　　The Smart Analog Output module reference design is intended as an evaluation module for users to develop end-equipment like PLC, field sensors and process transmitters. This design is an Isolated Analog Output Module with Digital isolators for SPI interface and FlyBuck transformer for power supply isolation. On-board EEPROM has been provided to store calibration data and module configuration.

　　Screw type terminals for individual output channels have been provided for easy wiring. LEDs are provided for Power Supply indication.

　　The reference design provides a complete guide for the design of an Analog Output Module that can be configured for Voltage or Current output, for different output ranges in a slim form factor. This Module has been designed to be pluggable to the IO Controller for quick testing and evaluation. This Module has been designed to comply with EMC standards for Industrial environment. The design files include schematics, BOM, layer plots, Altium files, Gerber Files and an easy-to-use Graphical User Interface (GUI).

　　The Smart Analog Output Module has been tested for the following:

　　 Isolated SPI Interface with DACs configures in daisy chain.

　　 Voltage and Current output functionality and accuracy including over range.

　　 Surge, EFT & ESD: Pre-compliance testing as per IEC61000-4 standards.

　　参考设计测试板TIDA-00118材料清单: