摘要：  本文介绍了AD5791产品亮点和主要特性， 方框图和菊花链接方框图，以及典型应用电路图和EVAL-AD5791评估板电路图，材料清单和PCB元件布局图.

关键字：  数模转换器，  医疗仪器，  PCB

ADI 公司的AD5791是单路20位电压输出数模转换器(DAC)，双极工作电压高达33V，正基准电压从5V到VDD-2.5V，负基准电压从VSS+2.5V到0V，精度1ppm，噪音频谱密度7.5 nV/√Hz，温度漂移0.05 ppm/°C，主要用在医疗仪器，测试测量，工业控制和高端科学和航空仪表.本文介绍了AD5791产品亮点和主要特性， 方框图和菊花链接方框图，以及典型应用电路图和EVAL-AD5791评估板电路图，材料清单和PCB元件布局图.

The AD5791 is a single 20-bit， unbuffered voltage-output DAC that operates from a bipolar supply of up to 33 V. The AD5791 accepts a positive reference input in the range 5 V to VDD 2.5 V and a negative reference input in the range VSS + 2.5 V to 0 V. The AD5791 offers a relative accuracy specification of ±1 LSB max， and operation is guaranteed monotonic with a ±1 LSB DNL maximum specification.

The part uses a versatile 3-wire serial interface that operates at clock rates up to 35 MHz and that is compatible with standard SPI， QSPI， MICROWIRE， and DSP interface standards. The part incorporates a power-on reset circuit that ensures the DAC output powers up to 0 V and in a known output impedance state and remains in this state until a valid write to the device takes place. The part provides an output clamp feature that places the output in a defined load state.

AD5791产品亮点:

　　1 ppm Accuracy.

　　Wide Power Supply Range up to ±16.5 V.

　　Operating Temperature Range: 40℃ to +125℃.

　　Low 7.5 nV/√Hz Noise Spectral Density.

　　Low 0.05 ppm/℃ Temperature Drift.

　　AD5791主要特性:

　　1 ppm resolution

　　1 ppm INL

　　7.5 nV/√Hz noise spectral density

　　0.19 LSB long term linearity stability

　　<0.05 ppm/℃ temperature drift

　　1 μs settling time

　　1 nV-sec glitch impulse

　　Operating temperature range:40℃ to +125℃

　　20-lead TSSOP package

　　Wide power supply range up to ±16.5 V

　　35 MHz Schmitt triggered digital interface

　　1.8 V compatible digital interface

　　AD5791应用:

　　Medical instrumentation

　　Test and measurement

　　Industrial control

　　High end scientific and aerospace instrumentation

　　图1.AD5791方框图

　　图2.AD5791菊花链接方框图

　　图3.AD5791典型应用电路图

　　EVAL-AD5791评估板

　　The EVAL-AD5791 is a full-featured evaluation board， designed to allow the user to easily evaluate all features of the AD5791 voltage output， 20-bit DAC. The AD5791 pins are accessible at on-board connectors for external connection. The board can be controlled by two means， via the on-board connector (J6) or via the system development platform connector (J3). The SDP board allows the evaluation board to be controlled through the USB port of a Windows® XP (SP2 or later) or Vista (32-bit) based PC using the AD5791 evaluation software.

　　EVAL-AD5791评估板主要特性:

　　Full-featured evaluation board for the AD5791

　　Link options

　　PC control in conjunction with Analog Devices， Inc.， system development platform

　　PC software for control

　　图4.EVAL-AD5791评估板连接框图

　　EVALUATION BOARD SCHEMATICS AND ARTWORK

　　图5.EVAL-AD5791评估板电路图(1)

　　图6.EVAL-AD5791评估板基准电压电路图

　　图7.EVAL-AD5791评估板SDP板连接器电路

　　图8.EVAL-AD5791评估板元件布局图

　　EVAL-AD5791评估板材料清单(BOM):