原标题：ADI AD4002 18位2 MSPS SAR ADC解决方案

　　ADI公司的AD4002是低噪声低功耗高速18 位取样频率2 MSPS 精密逐次逼近寄存器 (SAR) 模数转换器 (ADC),集成了多种易用特性,可以减少信号链功率,降低信号链复杂性以及实现更高的通道密度.INL最大为±3.2 LSB,18位不丢码,10kSPS时功耗70uW,2MSPS时为14mW,SNR在1kHz,VREF = 5 V时为95dB,THD在1 kHz,VREF = 5 V时为-125dB,主要用在自动测试设备,机器自动化,医疗器械,电池供电设备和精密数据采集系统.本文介绍了AD4002/AD4006/AD4010主要特性,功能框图,ADC简化电路图,典型应用框图,以及评估板EVAL-AD400xFMCZ主要特性,框图,电路图,材料清单和PCB设计图.

　　吞吐速率：最大 2 MSPS

　　积分非线性：最大 ±3.2 LSB

　　保证 18 位无失码

　　低功耗

　　2 MSPS 时为 9.75 mW(仅限 VDD)

　　10 kSPS 时为 70 μW，2 MSPS 时为 14 mW(合计)

　　信噪比：1 kHz 时为 95 dB(典型值)，100 kHz 时为 95 dB(典型值)

　　总谐波失真：1 kHz 时为 -125 dB(典型值)，100 kHz 时为 −108 dB(典型值)

　　易用特性降低了系统功率和复杂性

　　输入过压箝位电路

　　减少了非线性输入电荷反冲

　　高阻模式

　　长时间采集相位

　　输入范围压缩

　　快速转换时间允许较低的 SPI 时钟频率

　　SPI 可编程模式，读写能力，状态字

　　伪差分(单端)模拟输入范围：0 V 至 VREF，VREF 介于 2.4 V 至 5.1 V 之间

　　1.8 V 单电源供电，具有 1.71 V 至 5.5 V 逻辑接口

　　SAR 架构：无延时/流水线延迟

　　保证工作温度：-40°C 至 125°C

　　兼容串行接口 SPI/QSPI/MICROWIRE/DSP

　　可以通过菊花链连接多个 ADC 且具有繁忙指示器

　　10 引脚封装：3 mm × 3 mm LFCSP、3 mm × 4.90 mm MSOP

　　AD4002 是一款低噪声、低功耗、高速、18 位、2 MSPS 精密逐次逼近寄存器 (SAR) 模数转换器 (ADC)。它结合了多种易用特性，可以减少信号链功率、降低信号链复杂性以及实现更高的通道密度。高阻模式与长时间采集相位相结合，消除了对专用高功率、高速 ADC 驱动器的需要，因此使更多的低功耗精密放大器可以直接驱动此 ADC 并提供最佳的性能。输入范围压缩功能使 ADC 驱动放大器和 ADC 可以采用公用供电轨工作，而不必使用负电源，同时还保留了完整的 ADC 代码范围。较低的串行外设接口 (SPI) 时钟频率要求降低了数字输入/输出功耗，扩大了处理器选项，并简化了跨越数字隔离发送数据的任务。

　　AD4002 使用 1.8 V 电源进行工作，它可以对介于 0 V 至 VREF(相对于地感 (IN−))之间的模拟输入 (IN+) 进行采样，并且 VREF 的范围为 2.4 V 至 5.1 V。AD4002 在 2 MSPS 时仅消耗 14 mW，在涡流模式下具有最低 75 MHz SCK 速率，可以实现 ±3.2 LSB INL(最大值)，在分辨率为 18 位时无失码，并且信噪比为 95 dB。基准电压在外部应用，并且可以独立于电源电压进行设置。

　　与 SPI 兼容的通用串行接口配有七种不同的模式，包括能够使用 SDI 输入在单根 3 线式总线上以菊花链形式连接多个 ADC，并且提供可选的繁忙指示器。AD4002 使用单独的 VIO 电源，与 1.8 V、2.5 V、3 V 和 5 V 逻辑兼容。

　　AD4002 采用 10 引脚 MSOP 或 10 引脚 LFCSP 封装，可在 −40°C 至 +125°C 的温度范围内工作。此器件的引脚与 18 位 2 MSPS AD4003 兼容。

　　应用

　　自动测试设备

　　机器自动化

　　医疗器械

　　电池供电设备

　　精密数据采集系统

　　The AD4002/AD4006/AD4010 are low noise, low power, high speed, 18-bit, precision successive approximation register (SAR) analog-to-digital converters (ADCs). The AD4002, AD4006, and AD4010 offer 2 MSPS, 1 MSPS, and 500 kSPS throughputs, respectively. They incorporate ease of use features that reduce signal chain power consumption, reduce signal chain complexity, and enable higher channel density. The high-Z mode, coupled with a long acquisition phase, eliminates the need for a dedicated high power, high speed ADC driver, thus broadening the range of low power precision amplifiers that can drive these ADCs directly while still achieving optimum performance. The input span com-pression feature enables the ADC driver amplifier and the ADC to operate off common supply rails without the need for a negative supply while preserving the full ADC code range. The low serial peripheral interface (SPI) clock rate requirement reduces the digital input/output power consumption, broadens processor options, and simplifies the task of sending data across digital isolation.

　　Operating from a 1.8 V supply, the AD4002/AD4006/AD4010 sample an analog input (IN+) from 0 V to VREF with respect to a ground sense (IN−) with VREF ranging from 2.4 V to 5.1 V. The AD4002 consumes only 14 mW at 2 MSPS with a minimum SCK rate of 75 MHz in turbo mode; the AD4006 consumes only 7 mW at 1 MSPS; and the AD4010 consumes only 3.5 mW at 500 kSPS. The AD4002/AD4006/AD4010 all achieve ±3.2 LSB integral nonlinearity error (INL) maximum, no missing codes at 18 bits, and 95 dB signal-to-noise ratio (SNR) for an input frequency (fIN) of 1 kHz. The reference voltage is applied externally and can be set independently of the supply voltage.

　　The SPI-compatible versatile serial interface features seven different modes including the ability, using the SDI input, to daisy-chain several ADCs on a single 3-wire bus, and provides an optional busy indicator. The AD4002/AD4006/AD4010 are compatible with 1.8 V, 2.5 V, 3 V, and 5 V logic, using the separate VIO supply.

　　The AD4002/AD4006 are available in a 10-lead MSOP and 10-lead LFCSP, and the AD4010 is available in a 10-lead LFCSP, with operation specified from −40℃ to +125℃. The devices are pin compatible with the 18-bit, 2 MSPS AD4003 (see Table 8).

　　AD4002/AD4006/AD4010主要特性:

　　Throughput: 2 MSPS/1 MSPS/500 kSPS options

　　INL: ±3.2 LSB maximum

　　Guaranteed 18-bit, no missing codes

　　Low power: 70 μW at 10 kSPS, 14 mW at 2 MSPS (total)

　　9.75 mW at 2 MSPS, 4.9 mW at 1 MSPS, 2.5 mW at 500 kSPS (VDD only)

　　SNR: 95 dB typical at 1 kHz, VREF = 5 V; 95 dB typical at 100 kHz

　　THD: −125 dB typical at 1 kHz, VREF = 5 V; −108 dB typical at 100 kHz

　　Ease of use features reduce system power and complexity

　　Input overvoltage clamp circuit

　　Reduced nonlinear input charge kickback

　　High-Z mode

　　Long acquisition phase

　　Input span compression

　　Fast conversion time allows low SPI clock rates

　　SPI-programmable modes, read/write capability, status word

　　Pseudo differential (single-ended) analog input range

　　0 V to VREF with VREF from 2.4 V to 5.1 V

　　Single 1.8 V supply operation with 1.71 V to 5.5 V logic interface

　　SAR architecture: no latency/pipeline delay, valid first conversion

　　First conversion accurate

　　Guaranteed operation: −40℃ to +125℃

　　SPI-/QSPI-/MICROWIRE-/DSP-compatible serial interface

　　Ability to daisy-chain multiple ADCs and busy indicator

　　10-lead packages: 3 mm × 3 mm LFCSP, 3 mm × 4.90 mm MSOP

　　AD4002/AD4006/AD4010应用:

　　Automatic test equipment

　　Machine automation

　　Medical equipment

　　Battery-powered equipment

　　Precision data acquisition systems

　　评估板EVAL-AD400xFMCZ

　　The AD4000/AD4001/AD4002/AD4003/AD4020 family evaluation board covers the ease of use, 16-/18-/20-bit, precision successive approximation register (SAR) analog-to-digital converters (ADCs). The AD4000/AD4001/AD4002/ AD4003/AD4020 are low power, 16-bit/18-bit/20-bit, precision SAR ADCs that offer very high performance with throughputs up to 2 MSPS (1.8 MSPS for the AD4020). The evaluation board is designed to demonstrate the performance of the AD4000/AD4001/AD4002/AD4003/AD4020 family of ADCs and to provide an easy to understand interface for a variety of system applications. A full description of these products is available in their respective data sheets, which must be consulted when using this evaluation board.

　　The EVAL-AD4000FMCZ/EVAL-AD4001FMCZ/EVAL-AD4002FMCZ/EVAL-AD4003FMCZ/EVAL-AD4020FMCZ evaluation boards (see Figure 1) are ideal for use with the Analog Devices, Inc., high speed system demonstration platform (EVAL-SDP-CH1Z). These evaluation boards interface to the SDP-H1 board via a 120-pin connector. SMA connectors, JP2 and JP3, are provided for the low noise analog signal source.

　　On-board components include a high precision buffered band gap 5.0 V reference (the ADR4550), a reference buffer (the ADA4807-1), a common-mode buffer (the ADA4807-1), a signal conditioning circuit with two op amps (the ADA4807-1), and a power supply to derive the necessary voltage levels to supply all voltage needs.

　　The EVAL-AD4000FMCZ, EVAL-AD4001FMCZ, EVAL-AD4002FMCZ, and EVAL-AD4003FMCZ are populated with the AD4000, AD4001, AD4002, and AD4003, respectively. However, these boards can be used to evaluate the performance of the AD4004, AD4005, AD4006, AD4007, AD4008, AD4010, and AD4011 by limiting the sample rate in the evaluation software to the maximum sample rate of the specific ADC. For example, the AD4000 on the EVAL-AD4000FMCZ can be used to evaluate the performance of the AD4004 if the sample rate is limited to 1 MSPS. See the data sheet of each product for its corresponding evaluation board.

　　图.评估板EVAL-AD400xFMCZ外形图

　　评估板EVAL-AD400xFMCZ材料清单:

　　详情请见:

D4002.pdf