ADIAD578018位精度低噪音±10VDC电压源解决方案

ADI公司的AD5780是真正18位线性低噪音精密的±10 V DC电压源,工作电压双极电压高达33V,采用正基准输入电压从5V到VDD-2.5V,而负基准输入电压从VSS+2.5V到0V,输出噪音8 nV/√Hz,长期稳定性为0.025 LSB,增益误差±0.018 ppm/℃,输出电压设定时间2.5 μs, 施密特触发器数字接口35MHz,1.8V兼容数字接口,主要用在医疗仪器,测试测量,工业控制,数据采集系统,数字增益和失调调整,电源控制等.本文介绍了AD57801产品亮点和主要特性, 功能框图和典型工作电路图以及评估板EVAL-AD5780主要特性,电路图,材料清单和PCB布局图.

The AD57801 is a true 18-bit, unbuffered voltage output DAC that operates from a bipolar supply of up to 33 V. The AD5780 accepts a positive reference input range of 5 V to VDD ? 2.5 V and a negative reference input range of VSS + 2.5 V to 0 V. Both reference inputs are buffered on chip and external buffers are not required. The AD5780 offers a relative accuracy specifica-tion of ±1 LSB maximum range, and operation is guaranteed monotonic with a ±1 LSB DNL maximum range specification.

The part uses a versatile 3-wire serial interface that operates at clock rates of up to 35 MHz and is compatible with standard SPI, QSPI?, MICROWIRE?, and DSP interface standards. The part incorporates a power-on reset circuit that ensures that the DAC output powers up to 0 V 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.

AD57801产品亮点:

True 18-bit accuracy.

Wide power supply range of up to ±16.5 V.

?40℃ to +125℃ operating temperature range.

Low 8 nV/√Hz noise.

Low ±0.018 ppm/℃ gain error temperature coefficient

AD57801主要特性:

True 18-bit voltage output DAC, ±1 LSB INL

8 nV/√Hz output noise spectral density

0.025 LSB long-term linearity error stability

±0.018 ppm/°C gain error temperature coefficient

2.5 μs output voltage settling time

3.5 nV-sec midscale glitch impulse

Integrated precision reference buffers

Operating temperature range: ?40℃ to +125℃

4 mm × 5 mm LFCSP package

Wide power supply range of up to ±16.5 V

35 MHz Schmitt triggered digital interface

1.8 V-compatible digital interface

AD57801应用:

Medical instrumentation

Test and measurement

Industrial control

Scientific and aerospace instrumentation

Data acquisition systems

Digital gain and offset adjustment

Power supply control

图1.AD57801功能框图

图2.AD57801典型工作电路图

AD57801评估板EVAL-AD5780

Evaluation Board for a 18-Bit Serial Input, Voltage Output DAC with Integrated Precision Reference Buffer Amplifiers

The EVAL-AD5780 is a full-featured evaluation board, designed to allow the user to easily evaluate all features of the AD5780 voltage output, 18-bit digital-to-analog converter (DAC). The AD5780 pins are accessible at on-board connectors for external connection. The board can be controlled by two means: via the on-board connector (J3), or via the system development platform connector (J4). The SDP board allows the evaluation board to be controlled through the USB port of a Windows? XP- (SP2 or later) or Vista-based (32-bit) PC using the AD5780 evaluation software.

评估板EVAL-AD5780主要特性:

Full-featured evaluation board for the AD5780

Link options

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

PC software for control

图3.评估板EVAL-AD5780框图

图4.评估板EVAL-AD5780电路图:AD5780

图5.评估板EVAL-AD5780电路图:电压参考电路

图6.评估板EVAL-AD5780电路图:SDP板连接器

图7. 18位精度±10V电压源简化电路图
评估板EVAL-AD5780材料清单:




图8.评估板EVAL-AD5780 PCB布局图
详情请见:
http://www.analog.com/static/imported-files/data_sheets/AD5780.pdf
和
http://www.analog.com/static/imported-files/user_guides/UG-256.pdf