AD7791:4位、单通道、超低功耗Σ-Δ型ADC

AD7791: 4位、单通道、超低功耗Σ-Δ型ADC

AD7790/AD7791均为适合低频测量应用的低功耗、完整模拟前端。采用3 V电源时,二者的典型功耗为65 µA；采用5 V电源、禁用缓冲时,典型功耗为75 µA。AD7791内置一个24位Σ-Δ ADC,其中含有一个可缓冲或无缓冲差分输入。AD7790是AD7791的16位版本。AD7790在默认输出数据速率16.6 Hz时具有16位峰－峰值分辨率,而AD7789在此输出数据速率时则具有19位峰－峰值分辨率,相当于21.5位有效分辨率。

AD7791采用内部时钟工作,因此,用户不必为其提供时钟源。输出数据速率可通过软件编程设置,可在9.5 Hz至120 Hz的范围内变化。峰－峰值（p-p）分辨率随编程设置的输出数据速率不同而异。当输出数据速率为16.6 Hz时,可实现50 Hz/60 Hz同时抑制。两款器件还具有电源监控功能。

AD7791可在单次转换模式下使用,即上电后执行单次转换,然后返回省电模式。或者,也可以选择连续模式工作。在连续转换模式下,可将两款器件配置为连续读取,即假设已将串行时钟作用于这些器件,则一旦完成一次转换,便会自动将转换结果置于串行总线上（用户无需写入ADC以读取数据）。AD7790/AD7791采用10引脚MSOP封装。

The AD7790/AD7791 are low-power, complete analog front ends for low frequency measurement applications. The device consumes 65 µA of current typically when operated with a 3 V power supply and 75 µA typical when operated with a 5 V power supply with the buffer disabled. The AD7791 contains a 24-bit S-D ADC with one differential input, which can be buffered or unbuffered. The AD7790 is a 16-bit version of the AD7791. The AD7790 has a peak-to-peak resolution of 16 bits at the default output data rate of 16.6 Hz while the AD7789 has a peak to peak resolution of 19 bits, which is equivalent to an effective resolution of 21.5 bits at this output data rate.

The device operates from an internal clock. Therefore, the user does not have to supply a clock source to the device. The output data rate from the part is software programmable, allowing rates from 9.5 Hz to 120 Hz. The p-p resolution from the part varies with the programmed output data rate. With an output data rate of 16.6 Hz, simultaneous 50 Hz/60 Hz rejection is achieved. Power supply monitoring is also included.

The part can be used in single conversion mode whereby the device powers up, performs a single conversion and then returns to powerdown mode. Alternatively, it can be operated in continuous mode. In continuous conversion mode, the part can be configured to continuously read i.e. the conversions are placed on the serial bus automatically as soon as a conversion is complete (the user does not need to write to the ADC to read the data), assuming that the serial clock is applied to the device.

AD7791 特点

电源：
- 工作电压：2.5 V至5.25 V
- 正常模式：最大75 µA
- 省电模式：最大1 µA
均方根（RMS）噪声：1.1 µV（9.5 Hz更新速率时）
19.5位峰－峰值分辨率（22位有效分辨率）
积分非线性：3.5 ppm（典型值）
50 Hz和60 Hz同时抑制
内部时钟振荡器
轨到轨输入缓冲
VDD监控通道
温度范围：-40°C ～ +105°C
10引脚MSOP封装
Power
- Supply: 2.5 V to 5.25 V operation
- Normal: 75 µA maximum
- Power-down: 1 µA maximum
RMS noise: 1.1 µV at 9.5 Hz update rate
19.5-bit p-p resolution (22 bits effective resolution)
Integral nonlinearity: 3.5 ppm typical
Simultaneous 50 Hz and 60 Hz rejection
Internal clock oscillator
Rail-to-rail input buffer
VDD monitor channel
Temperature range: –40°C to +105°C
10-lead MSOP

AD7791 技术指标

Resolution (Bits): 24bit
# Chan: 1
Sample Rate: n/a
Interface: Ser,SPI
Analog Input Type: Diff-Uni
Ain Range: (2Vref) p-p
ADC Architecture: Sigma-Delta
Pkg Type: SOP

AD7791 建议配套产品

推荐AD7791使用的基准电压源

针对非比率应用，推荐使用ADR381 或 ADR391 低噪声、低功耗2.5V基准电压源。
- 针对系统采用2.5V电源供电的非比率应用，推荐使用2.048V基准电压源ADR380 或 ADR390。
推荐AD7791使用的精密放大器
- 针对低噪声和低功耗应用，推荐使用ADA4051-2。
- 如需更高精度和更好的温漂特性，推荐使用 AD8539。
- 针对最高±8V的高电源电压，推荐使用 AD8639。
推荐电源解决方案
- 欲选择电压调节器产品，请使用ADIsimPower。
- 欲选择电源监控器产品，请使用电源监控器参数搜索。

AD7791 功能框图

AD7791 芯片订购指南

产品型号	产品状态	封装	引脚	温度范围
AD7791BRM	Prodn	10 ld MSOP	10	工业
AD7791BRM-REEL	Prodn	10 ld MSOP	10	工业
AD7791BRMZ	Prodn	10 ld MSOP	10	工业
AD7791BRMZ-REEL	Prodn	10 ld MSOP	10	工业
EVAL-AD7791EB	Prodn	EVALUATION BOARDS	-	待定