• AD7690: FAQ

    FAQ

  • AD7690 SPI Mode SDo High Impedance State

    Q 

    I would like to make sure the AD7690 SDO pin stays in high impedance when I do
    not need to use it?

     

    A 

    SDO is high impedance whenever the ADC is not selected, i.e. when SDI is high.

     

  • AD7690 PMOD eval software questions

    Hi,

    While I am using PulSAR ADC PMODs and picked AD7690. I have the findings and questions listed below.

    1. It limits the maximum sampling frequency to 244 kSPS instead of the full speed 400 kSPS, is this true or just some limitations in my side?
    …

  • AD7690的SNR

    我在计算过采样对AD7690 SNR的改善。

    公式如下。在我的应用中，带宽为150Hz。但我不确定N的值。对于AD7690，N应当是18位还是16.6位？

    Attachments:

  • AD7690 Readings / Output code

    Hello,

    Hopefully someone may be able to help me out...

    I am testing out an AD7690 18-bit ADC for an application. Currently I can get a reading from the ADC, though it is not what I expect.

    Vref is set to 2.048 V and there is 1.45 V onto IN+, IN- is…

  • 微弱信号输入情况下AD7690采集误差较大问题请教。

    现在有个项目，传感器信号输入为-5~+5v， 经过AD8475进行0.4倍衰减并移位到2.5伏后，再差分进入AD7690进行数据采集。当该传感器输入电压很小时，AD7690差分数据采集偏差很大；但如果传感器输入电压较大时，AD7690差分数据采集很准。  

    具体如下表：

    AD7690输入差分电压               AD7690输出结果

         0.4mv                                          2mv附近跳动，最大到5mv

         1mv                                             4mv附近跳动，最大到8mv

         2mv                                             比较准确

         3mv                                             很准

         。。。                                         很准

    电路连接是参考AD8475与AD7690的数据手册中的推荐电路的…

  • RE: About AD7690 ADC

    Hi Vijay,

    Sorry for the late reply. The AD7690 is a fully differential input. This means the positive and negative inputs must be antiphase around the common mode voltage Vref/2, the IN- pin cannot be tied to ground for proper operation. Is 18 bit performance…

  • AD8295 to AD7690 Reference Design Problem

    I recently built the reference design included with the AD8295 datasheet, which uses the AD8295 to differentially drive an AD7690 ADC chip.  This is a very compact implementation but I can't seem to get it to work correctly.

    That said, I notice that…

    • AD8295.pdf

  • ADI年度贺岁片-----AD7690帮我应对高精度的传感器数据采集

    1.数模转换

       传感器出来的数据一般都是模拟量，也就是我们通常所说的电压值（当然也有电流值的，这时我们可以通过一个精密电阻把其转换为电压值）。如果把这些模拟量变成计算机能够处理的数字量呢？这时就要使用我们的数模转换器，俗称AD。

       在我的这个项目中，模拟量的提供者是一个非常灵敏并且线性度很好的水平传感器，该传感器的满量程输出为5V/14.5°，按次推算如果采用3.3v基准的16位AD则其分辨率为0.00014°，采用3.3v基准的18位AD则其分辨率为0.000036°。（不考虑各种误差）

    …

  • I got some samples of the AD7691 and connected it to the SPORT of an ADSP21161N.

    Q 

    I got some samples of the AD7691 and connected it to the SPORT of an
    ADSP21161N. I found a strange behaviour of the ADC and I have no idea why. I
    connected a constant voltage to the positive input of the device (the negative
    input is grounded…