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型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为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。AD7790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。器件的峰－峰值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。AD7790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.The AD7790/AD7791 is housed in a 10-lead MSOP package.
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