原标题：TI DAC7678低功耗8路12位数模转换解决方案

　　TI 公司的DAC7678是低功耗电压输出8路12位数模转换器(DAC),包括有2.5V内部基准电压,精度±5mV,满刻度输出电压范围5V,通用两线I2C兼容的串行接口, 时钟速率高达3.4MHz,典型温度漂移5ppm/℃,工作电压+2.7V 到+5.5V,主要用在手提仪表和闭环伺服控制.本文介绍了DAC7678主要特性,方框图, 单个和多个器件的典型连接框图, 评估板DAC7678EVM主要特性,以及评估板电路图和材料清单(BOM).

　　The DAC7678 is a low-power, voltage-output, octal channel, 12-bit digital-to-analog converter (DAC). The DAC7678 includes a 2.5V internal reference (disabled by default), giving a full-scale output voltage range of 5V. The internal reference has an initial accuracy of ±5mV and can source up to 20mA at the VREFIN/VREFOUT pin. The device is monotonic, provides very good linearity, and minimizes undesired code-to-code transient voltages (glitch).

　　The DAC7678 uses a versatile, 2-wire serial interface that is I2C-compatible and operates at clock rates of up to 3.4MHz. Multiple devices can share the same bus.

　　The DAC7678 incorporates a power-on-reset circuit that ensures the DAC output powers up to either zero-scale or mid-scale until a valid code is written to the device.

　　DAC7678主要特性:

　　Relative Accuracy:

　　1 LSB INL

　　Glitch Energy: 0.15nV-s

　　Internal Reference:

　　2.5V Reference Voltage (disabled by default)

　　±5mV Initial Accuracy (max)

　　5ppm/℃ Temperature Drift (typ)

　　25ppm/℃ Temperature Drift (max)

　　20mA Sink/Source Capability

　　Power-On Reset to Zero Scale or Midscale

　　Devices in the TSSOP Package Reset to Zero Scale

　　Devices in the QFN Package Reset to Zero Scale or Midscale

　　Ultra-Low Power Operation: 0.13mA/Channel at 5V (without internal reference current)

　　Wide Power-Supply Range: +2.7V to +5.5V

　　2-Wire Serial Interface (I2C compatible)

　　On-Chip Output Buffer Amplifier with Rail-to-Rail Operation

　　Temperature Range: –40℃ to +125℃

　　DAC7678应用:

　　Portable Instrumentation

　　Closed-Loop Servo-Control

　　图1.DAC7678方框图

　　图2.DAC7678典型连接框图

　　图3.同一总线多个DAC7678连接框图

　　DAC7678EVM评估板

　　The DAC7678EVM is designed to give the user access to all pins on the DAC7678. The evaluation module allows the user to control the DAC logic using on board jumpers, or digitally through the J2 header. By default, the evaluation module is configured to be used with an onboard external reference, but can be easily modified to use the DAC internal reference by changing a jumper setting and enabling the internal reference using software.

　　The DAC7678EVM is an evaluation module built to the TI Modular EVM System specification. It can be connected to any modular EVM system interface card.

　　This user’s guide describes the characteristics, operation, and use of the DAC7678EVM. The evaluation model (EVM) is an evaluation board for the DAC7678. The DAC7678 is a low-power, voltage-output, octal, 12-bit digital-to-analog converter (DAC). The converter is controlled by an I2C™ interface that can operate at clock rates of up to 3.4MHz. Additionally, this DAC includes a 2.5V internal reference voltage (disabled by default), giving a full-scale output range of 5V. The EVM allows evaluation of all aspects of the device and allows user control over every pin on the DAC7678. Complete circuit descriptions, schematic diagrams, and bills of material are included in this document.

　　DAC7678EVM评估板主要特性:

　　• Full-featured evaluation board for the DAC7678

　　• Onboard optional external reference selection

　　• Wide selection of digital and I/O voltages

　　• Hardware or software control of control logic

　　• Compatible with the TI Modular EVM System

　　图4.DAC7678EVM评估板外形图

　　图5.DAC7678EVM评估板电路图

　　DAC7678EVM评估板材料清单(BOM):